BAWiki - User contributions [en]

Etho-hydraulic tests at the BAW

2022-05-20T12:23:14Z

BAWiki Glossar: Created page with "Etho-hydraulic test station at the BAWSo-called etho-hydraulic tests serve to gain an understanding of how water flow influences fish..."

[[File:Ethohydraulik_01.jpg|thumb|200px|Etho-hydraulic test station at the BAW]]So-called etho-hydraulic tests serve to gain an understanding of how water flow influences fish behaviour and use this to set out corresponding requirements for an approach to hydraulic engineering that is sustainable from the point of view of fish ecology. The discipline of etho-hydraulics combines ethology (comparative behaviour research) with hydraulics. These tests are designed and conducted by an interdisciplinary team of researchers from the Federal Waterways Engineering and Research Institute (BAW) and the German Federal Institute of Hydrology (BfG) specialising in hydraulics and behavioural and fish ecology respectively.

[[File:Ethohydraulik_02.jpg|thumb|200px|Fish test using nases]]The animal behaviours observed in the laboratory under reproducible conditions have to be transferrable to real-life situations. To this end, the geometric and hydraulic boundary conditions of the test structure must be similar to those occurring in nature. This requires as large a scale model as possible (ideally 1:1); however, the drawback of this is that the modelling process is restricted since only a small number of external factors can be taken into account.

Fish behaviour is documented during the test by logging data manually, measuring times and taking video recordings and measuring the hydraulic conditions in detail. The findings from these tests help to identify advantageous or disadvantageous effects of certain flow patterns or structural designs on fish behaviour, with various statistical methods used to evaluate the test data.

Etho-hydraulic tests cannot be carried out without permission in accordance with the German Animal Protection Act (Tierschutzgesetz). They require special qualifications in fish biology as well as adequate infrastructure. An etho-hydraulic test station was set up at the BAW in spring 2016 in partnership with the BfG. It was placed in a test flume measuring 2.5 metres wide by some 60 metres long. This required installing new pumps and storage tanks and creating a separate water circuit.

The fish tests at the BAW are focusing on the navigability of fish ladders. These tests form part of a joint BfG/BAW R&D project to establish a measurement framework for dimensioning effective fish ladders on Germany's federal waterways.
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[[Overview]]

[[de:Ethohydraulische Versuche an der BAW]]

File:Ethohydraulik 02.jpg

2022-05-20T12:20:59Z

BAWiki Glossar:

File:Ethohydraulik 01.jpg

2022-05-20T12:20:27Z

BAWiki Glossar:

Geotechnical measurements

2022-05-20T11:58:53Z

BAWiki Glossar:

[[File:01_Methoden_02.jpg|200px|thumb|right|Picture 1: Vibration measurements at the bank]]Geotechnical measurements (static, dynamic, [[Hydraulics|hydraulic]]) serve on the one hand to [[Monitoring|monitor]] earthworks and structures after completion or during new construction work. On the other hand, they are indispensable when designing building structures on the basis of the observation method, when numerical predictions for various stages of construction progress are compared with real behaviour. It is thus possible to optimize the on-going computing steps.

== Geomechanical measurements ==
[[File:04_G_Messungen_01.jpg|200px|thumb|right|Picture 2: Measuring system installed in the bottom of a drained lock chamber]]Standard measurements include the loading tests on piles and anchors as stipulated in the standards. Measurements are also carried out at slopes, retaining structures and foundations for the preservation of evidence and when using the observational method. Measurements at structures, foundation elements, in the ground and on models can be useful for design in cases where neither theoretical principles nor practical experience is available to provide reliable, economic solutions for geotechnical problems in waterways engineering.

== Measuring groundwater level and pressure ==

[[File:04_G_Messungen_02.jpg|200px|thumb|right|Picture 3: Sheet piling thickness being measured by a diver]]Geohydraulic measurements are needed both for ascertaining the existing groundwater conditions and for forecasting changes caused by work carried out in the federal waterways in the framework of planning approval procedures or hydrogeological expert opinions, for the conservation of groundwater evidence, for ascertaining groundwater pressure and current loads on concrete and earthwork structures or excavation pits, and for monitoring building structures.
[[Measuring groundwater level and pressure]]

== Geodynamic measurements ==

[[File:04_G_Messungen_03.jpg|200px|thumb|right|Picture 4: Measuring pendulum in Edertal dam]]Geodynamic measurements are used to ascertain the emission, propagation and impact of vibrations caused by construction work and operation at and on waterways. Vibrations in waterways are generated for example when [[Installation|installing]] sheet piling, during loosening and demolition blasting, during chiselling work, during surface and in-depth compaction of the ground, from propulsion systems of vessels, from vessel impact when mooring and from stationary systems such as pumps and machines, together with the flow forces, e.g. at locks.

== Measuring the thickness of sheet piles ==

Non-destructive methods using ultrasound equipment are carried out to assess the stability and serviceability of sheet piling structures. The measuring results are used to estimate the residual service life of existing structures (stability) and to forecast the point in time of the first signs of rust perforation (serviceability).

[https://www.youtube.com/watch?v=SACPZR_4ZCc Pfahlwanddickenmessung]
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back to: [[Geotechnical Engineering Methods]]
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[[Overview]]
[[de:Geotechnische Messungen]]

Geotechnical field tests

2022-05-20T11:54:20Z

BAWiki Glossar: /* Geohydraulic field tests */

Field tests include alongside direct ground explorations (borings and trial pits), indirect exploration methods using sounding apparatus, as well as geophysical and seismic measurements. The indirect methods make it possible to explore the condition of the ground while causing only minimum disturbance, if any, to the ground structure.

== Direct ground exploration ==

Direct ground exploration is usually contracted out to suitable companies while the Federal Waterways and Shipping Offices are responsible for supervision. Well drilling experts from BAW carry out random checks. In special cases, driven core sounding and hollow stem auger drilling is carried out by BAW staff.

== Indirect exploration methods ==

For indirect exploration, field tests are carried out partly by BAW and partly by external companies to obtain results that allow conclusions to be drawn about the structure of the ground and its properties. BAW uses the following geotechnical equipment and methods:

* Dynamic probing light (DHL)
* Dynamic probing heavy (DPH)
* (modified) standard penetration test (BDP)
* Cone penetration test (CPT)
* Flat dilatometer
* Air pressure probing
* Field vane test
* In-situ determination of density
* Freeze core sampling
* Plate Load test
* Dynamic plate load test

== Geophysical measurements ==

Geophysical measurements are used to establish soil [[Model|models]] or investigate geological and [[Anthropogen|anthropogenic]] disturbance zones and bodies. The appropriate deployment of geophysical methods depends on the presence of contrasts in the physical parameters of the ground (density, specific electrical resistance, dielectric constant, velocity of seismic waves, etc.)

The following methods are used:

* Geoelectric methods
* Seismic methods
* Georadar
* Borehole geophysical methods

== Geodynamic field tests ==

BAW has developed low-cost field tests and analysis procedures for replacing elaborate and expensive methods such as trial pile driving and trial detonations. These consist of:

* Simulating pile hammer
* Simulating vibratory driving
* Underwater trial detonations for simulation the vibrations caused by detonation for the demolition of structures under water

== Geohydraulic field tests ==

The use of different field test methods allows the geohydraulic properties of aquifers, e.g. their [[Hydraulics|hydraulic]] conductivity or [[Specific storage coefficient|specific storage coefficients]], to be calculated and groundwater flow velocities to be recorded in situ. Depending on the boundary conditions of the specific site and the issues being investigated, the BAW will choose suitable techniques from a wide range of test methods, accompany the execution of the tests and evaluate the test results. Tests include:

* Pump tests for the calculation of the large-scale conductivity and storage properties of an aquifer,
* Hydraulic borehole tests (constant rate injection, drill-stem, slug-and-bail and water pressure tests) to calculate local conductivity and storage values in the vicinity of the borehole,
* (Thermal mass) flow meter measurements to find out preferential inflow zones in boreholes or near well screens,
* Thermal measurements to locate leaks in impervious canal bed linings,
* Tracer tests (introducing natural and artificial tracers into the aquifer) to plot groundwater flows,
* Groundwater sampling to calculate the concentrations of substances in the water.
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back to: [[Geotechnical Engineering Methods]]
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[[Overview]]
[[de:Geotechnische Feldversuche]]

Interaction of ground and building structure

2022-05-20T11:52:09Z

BAWiki Glossar:

[[File:06_Numerische_V_02.jpg|200px|thumb|right|Picture 1: 3D model of the excavation pit for Sülfeld lock]]Deformation and stability calculations for building structures used in waterways engineering are increasingly carried out using the finite element method (FEM) and in recent years also the distinct element method (DEM). The advantage of FEM is that it can be used to visualize complex geometries and ground conditions, and also indicates interaction between building structure and the ground.

[[File:10_Wechselwirkung_B_B_01.jpg|200px|thumb|right|Picture 2: Deformed 2D model of Minden lock (river Weser)]]The aforementioned advantages of the method play an important role particularly in view of the increasing complexity of construction work, for example when building excavation pits right next to structures that are susceptible to deformation during the construction of new structures next to existing locks while the waterway continues normal shipping operations, or during subsequent calculation of load-bearing and deformation behaviour of existing building structures.

[[File:10_Wechselwirkung_B_B_02.jpg|200px|thumb|right|Picture 3: Ension settlement curves from the oedometer test and subsequent FEM calculation]]
[[File:10_Wechselwirkung_B_B_03.jpg|200px|thumb|right|Picture 4: DEM simulation of armourstones ]]Depending on requirements, 2D or 3D models are designed to solve the geotechnical problem. Various different material models are available for describing the mechanical behaviour of the soil. The necessary soil characteristics can be calibrated with the results from [[Geotechnical field tests|field tests]], geotechnical measurements und laboratory tests for example by numerical simulation of an oedometer experiment. Realistic computation results are obtained by visualising the complete load history of the system consisting of building structure and ground, i.e. the sequence of construction phases and conditions that are planned for implementation of the construction work. This also takes account of the changing general hydraulic conditions. Attempts are also increasingly being made to ensure that the modelling phase also takes account of the effects resulting from production of the geotechnical structures (e.g. piles, subterraneous curtains).

DEM offers the possibility of overcoming the limits of FEM when it comes to large net deformation when dealing with geometric bodies such as boulders or spheres. In many cases, the calculations can be simplified by concentrating on spherical shapes which are then put together to generate other geometries such as polygonal armourstones.
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back to: [[Numerical Methods]]
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[[Overview]]
[[de:Wechselwirkung Boden-Bauwerk]]

Groundwater models

2022-05-20T11:49:52Z

BAWiki Glossar:

[[File:09_Grundwassermodelle_01.jpg|200px|thumb|right|Picture 1: Groundwater model for retention area weir, Kehl]]
[[File:09_Grundwassermodelle_02.jpg|200px|thumb|right|Picture 2: Transient dam saturation caused by a leak in the canal lining]]The basis for calculating groundwater and seepage flows is their description using mathematical models. Numerical computational methods based on the finite element method (FEM) or the finite difference method (FDM) offer a suitable range of instruments for dealing with complex geohydraulic issues. These computational models enable the spatial variability of the ground and external inflows as well as the change in the water saturation conditions to be taken into account. Computational groundwater flow models are used to investigate a wide range of issues, including:

* to determine the impact of construction measures in waterways on the large-scale groundwater conditions,
* to search for alternatives for minimising unwanted impacts of construction measures on the existing groundwater system,
* to ascertain the forces resulting from groundwater flow on the ground and on the structure and
* to compare suitable groundwater drainage or relief measures for reducing unwanted groundwater effects.

[[File:06_Numerische_V_01.jpg|200px|thumb|right|Picture 3: Groundwater model for the excavation pit for Minden lock]]The use of numerical groundwater models can entail differing levels of spatial resolution (one-dimensional, two-dimensional along a horizontal or vertical plane, three-dimensional) and complexity (steady-state/transient, saturated/unsaturated), depending on the specific issue and on the available data.

[[File:09_Grundwassermodelle_03.jpg|200px|thumb|right|Picture 4: Groundwater model (quarter model) for a dam with culvert structure]]Vertical-plane calculations are suitable for groundwater flows that occur with elongated [[Building structure|building structures]] with largely unchanging hydraulic boundary conditions and presumably negligible flow normal to the computational plane (e.g. flow through a canal or river embankment). In the case of flows with a free groundwater surface where the part of the model domain which is saturated with water is not known in advance or changes during the time period observed, a saturated/unsaturated numerical flow calculation is carried out (e.g. to determine the impact of [[Flood|floods]] or rapid water level fluctuations on the flow through an embankment). In the unsaturated zone, the functional interrelationship between pore water pressure, degree of saturation and hydraulic conductivity must be taken into account. Given that these relationships of soil hydraulics are non-linear, the numerical calculation requires much more time and effort than in the case of completely water-saturated flows.

3D numerical calculation of the groundwater flow is required if the geometric situation or the hydraulic boundary conditions result in a pronounced 3D flow field that cannot be represented adequately by simplified groundwater models. This is usually the case, for example, with groundwater modelling of flows around a building structure to determine the forces resulting from groundwater pressure and flow. Three-dimensional modelling, particularly when taking account of saturated/unsaturated flows, requires an in-depth knowledge of geohydraulics and the relevant numerical computational methods, together with extensive experience in modelling.

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back to: [[Numerical Methods]]
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[[Overview]]
[[de:Grundwassermodelle]]

Groundwater models

2022-05-20T11:48:17Z

BAWiki Glossar:

[[File:09_Grundwassermodelle_01.jpg|200px|thumb|right|Picture 1: Groundwater model for retention area weir, Kehl]]
[[File:09_Grundwassermodelle_02.jpg|200px|thumb|right|Picture 2: Transient dam saturation caused by a leak in the canal lining]]The basis for calculating groundwater and seepage flows is their description using mathematical models. Numerical computational methods based on the finite element method (FEM) or the finite difference method (FDM) offer a suitable range of instruments for dealing with complex geohydraulic issues. These computational models enable the spatial variability of the ground and external inflows as well as the change in the water saturation conditions to be taken into account. Computational groundwater flow models are used to investigate a wide range of issues, including:

* to determine the impact of construction measures in waterways on the large-scale groundwater conditions,
* to search for alternatives for minimising unwanted impacts of construction measures on the existing groundwater system,
* to ascertain the forces resulting from groundwater flow on the ground and on the structure and
* to compare suitable groundwater drainage or relief measures for reducing unwanted groundwater effects.

[[File:08_Grundwasserstroemung_03.jpg|200px|thumb|right|Picture 3: Groundwater model for the excavation pit for Minden lock]]The use of numerical groundwater models can entail differing levels of spatial resolution (one-dimensional, two-dimensional along a horizontal or vertical plane, three-dimensional) and complexity (steady-state/transient, saturated/unsaturated), depending on the specific issue and on the available data.

[[File:06_Numerische_V_01.jpg|200px|thumb|right|Picture 4: Groundwater model (quarter model) for a dam with culvert structure]]Vertical-plane calculations are suitable for groundwater flows that occur with elongated [[Building structure|building structures]] with largely unchanging hydraulic boundary conditions and presumably negligible flow normal to the computational plane (e.g. flow through a canal or river embankment). In the case of flows with a free groundwater surface where the part of the model domain which is saturated with water is not known in advance or changes during the time period observed, a saturated/unsaturated numerical flow calculation is carried out (e.g. to determine the impact of [[Flood|floods]] or rapid water level fluctuations on the flow through an embankment). In the unsaturated zone, the functional interrelationship between pore water pressure, degree of saturation and hydraulic conductivity must be taken into account. Given that these relationships of soil hydraulics are non-linear, the numerical calculation requires much more time and effort than in the case of completely water-saturated flows.

3D numerical calculation of the groundwater flow is required if the geometric situation or the hydraulic boundary conditions result in a pronounced 3D flow field that cannot be represented adequately by simplified groundwater models. This is usually the case, for example, with groundwater modelling of flows around a building structure to determine the forces resulting from groundwater pressure and flow. Three-dimensional modelling, particularly when taking account of saturated/unsaturated flows, requires an in-depth knowledge of geohydraulics and the relevant numerical computational methods, together with extensive experience in modelling.

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back to: [[Numerical Methods]]
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[[Overview]]
[[de:Grundwassermodelle]]

Groundwater models

2022-05-20T11:39:04Z

BAWiki Glossar:

[[File:08_Grundwasserstroemung_01.jpg|200px|thumb|right|Picture 1: Groundwater model for retention area weir, Kehl]]
[[File:08_Grundwasserstroemung_02.jpg|200px|thumb|right|Picture 2: Transient dam saturation caused by a leak in the canal lining]]The basis for calculating groundwater and seepage flows is their description using mathematical models. Numerical computational methods based on the finite element method (FEM) or the finite difference method (FDM) offer a suitable range of instruments for dealing with complex geohydraulic issues. These computational models enable the spatial variability of the ground and external inflows as well as the change in the water saturation conditions to be taken into account. Computational groundwater flow models are used to investigate a wide range of issues, including:

* to determine the impact of construction measures in waterways on the large-scale groundwater conditions,
* to search for alternatives for minimising unwanted impacts of construction measures on the existing groundwater system,
* to ascertain the forces resulting from groundwater flow on the ground and on the structure and
* to compare suitable groundwater drainage or relief measures for reducing unwanted groundwater effects.

[[File:08_Grundwasserstroemung_03.jpg|200px|thumb|right|Picture 3: Groundwater model for the excavation pit for Minden lock]]The use of numerical groundwater models can entail differing levels of spatial resolution (one-dimensional, two-dimensional along a horizontal or vertical plane, three-dimensional) and complexity (steady-state/transient, saturated/unsaturated), depending on the specific issue and on the available data.

[[File:08_Grundwasserstroemung_04.jpg|200px|thumb|right|Picture 4: Groundwater model (quarter model) for a dam with culvert structure]]Vertical-plane calculations are suitable for groundwater flows that occur with elongated [[Building structure|building structures]] with largely unchanging hydraulic boundary conditions and presumably negligible flow normal to the computational plane (e.g. flow through a canal or river embankment). In the case of flows with a free groundwater surface where the part of the model domain which is saturated with water is not known in advance or changes during the time period observed, a saturated/unsaturated numerical flow calculation is carried out (e.g. to determine the impact of [[Flood|floods]] or rapid water level fluctuations on the flow through an embankment). In the unsaturated zone, the functional interrelationship between pore water pressure, degree of saturation and hydraulic conductivity must be taken into account. Given that these relationships of soil hydraulics are non-linear, the numerical calculation requires much more time and effort than in the case of completely water-saturated flows.

3D numerical calculation of the groundwater flow is required if the geometric situation or the hydraulic boundary conditions result in a pronounced 3D flow field that cannot be represented adequately by simplified groundwater models. This is usually the case, for example, with groundwater modelling of flows around a building structure to determine the forces resulting from groundwater pressure and flow. Three-dimensional modelling, particularly when taking account of saturated/unsaturated flows, requires an in-depth knowledge of geohydraulics and the relevant numerical computational methods, together with extensive experience in modelling.

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back to: [[Numerical Methods]]
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[[Overview]]
[[de:Grundwassermodelle]]

Measuring groundwater level and pressure

2022-05-20T11:20:49Z

BAWiki Glossar:

[[File:04_G_Messungen_01.jpg|200px|thumb|right|Measuring system [[Installation|installed]] in the bottom of a drained lock chamber]]Groundwater level and pressure are measured in order to assess the groundwater conditions in the vicinity of the federal waterways. These measurements form the basis for predicting changes to groundwater conditions caused by construction measures within the framework of hydrogeological expert reports, for determining groundwater pressure and flow actions on concrete and earthwork structures or excavation pits, for collecting groundwater evidence and for monitoring the groundwater around structures.

Groundwater level and pressure measurements can be taken in open or closed groundwater observation wells. Open groundwater observation wells are used for soils or rock with medium to high hydraulic conductivity. They consist of a filter and a standpipe that extends to the ground surface and that enables atmospheric pressure to be compensated for. In open groundwater observation wells, the water level in the standpipe is measured either manually using a light plummet or automatically by means of a pressure transducer in the standpipe, with the measurements being stored on a data logger. However, they are only of limited use when it comes to measuring rapid changes of pore water pressure in less [[Permeability|permeable]] soils or rock, in which case closed groundwater observation wells are used. These consist of a pressure transducer surrounded by a sealed filter zone, which is fitted directly into the ground. The measured data are recorded by a data logger [[Installation|installed]] on the ground surface.

BAW creates detailed project-specific guidelines for the selection and development of the groundwater measuring system together with appropriate procedures in accordance with local conditions and the necessary data. It monitors the preparation of the measuring wells and the installation of the measuring technology and analyses the measurements. Specific measurement systems are developed for particular requirements (e.g. measuring groundwater pressure under [[Weir|weirs]] and lock beds).

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back to: [[Geotechnical measurements]]
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[[Overview]]
[[de:Grundwasserstands- und -druckmessungen]]

Geotechnical measurements

2022-05-20T11:10:03Z

BAWiki Glossar: /* Geodynamic measurements */

[[File:01_Methoden_01.jpg|200px|thumb|right|Picture 1: Vibration measurements at the bank]]Geotechnical measurements (static, dynamic, [[Hydraulics|hydraulic]]) serve on the one hand to [[Monitoring|monitor]] earthworks and structures after completion or during new construction work. On the other hand, they are indispensable when designing building structures on the basis of the observation method, when numerical predictions for various stages of construction progress are compared with real behaviour. It is thus possible to optimize the on-going computing steps.

== Geomechanical measurements ==
[[File:04_G_Messungen_01.jpg|200px|thumb|right|Picture 2: Measuring system installed in the bottom of a drained lock chamber]]Standard measurements include the loading tests on piles and anchors as stipulated in the standards. Measurements are also carried out at slopes, retaining structures and foundations for the preservation of evidence and when using the observational method. Measurements at structures, foundation elements, in the ground and on models can be useful for design in cases where neither theoretical principles nor practical experience is available to provide reliable, economic solutions for geotechnical problems in waterways engineering.

== Measuring groundwater level and pressure ==

[[File:04_G_Messungen_02.jpg|200px|thumb|right|Picture 3: Sheet piling thickness being measured by a diver]]Geohydraulic measurements are needed both for ascertaining the existing groundwater conditions and for forecasting changes caused by work carried out in the federal waterways in the framework of planning approval procedures or hydrogeological expert opinions, for the conservation of groundwater evidence, for ascertaining groundwater pressure and current loads on concrete and earthwork structures or excavation pits, and for monitoring building structures.
[[Measuring groundwater level and pressure]]

== Geodynamic measurements ==

[[File:04_G_Messungen_03.jpg|200px|thumb|right|Picture 4: Measuring pendulum in Edertal dam]]Geodynamic measurements are used to ascertain the emission, propagation and impact of vibrations caused by construction work and operation at and on waterways. Vibrations in waterways are generated for example when [[Installation|installing]] sheet piling, during loosening and demolition blasting, during chiselling work, during surface and in-depth compaction of the ground, from propulsion systems of vessels, from vessel impact when mooring and from stationary systems such as pumps and machines, together with the flow forces, e.g. at locks.

== Measuring the thickness of sheet piles ==

Non-destructive methods using ultrasound equipment are carried out to assess the stability and serviceability of sheet piling structures. The measuring results are used to estimate the residual service life of existing structures (stability) and to forecast the point in time of the first signs of rust perforation (serviceability).

[https://www.youtube.com/watch?v=SACPZR_4ZCc Pfahlwanddickenmessung]
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back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Geotechnische Messungen]]

Geotechnical measurements

2022-05-20T11:08:52Z

BAWiki Glossar:

[[File:01_Methoden_01.jpg|200px|thumb|right|Picture 1: Vibration measurements at the bank]]Geotechnical measurements (static, dynamic, [[Hydraulics|hydraulic]]) serve on the one hand to [[Monitoring|monitor]] earthworks and structures after completion or during new construction work. On the other hand, they are indispensable when designing building structures on the basis of the observation method, when numerical predictions for various stages of construction progress are compared with real behaviour. It is thus possible to optimize the on-going computing steps.

== Geomechanical measurements ==
[[File:04_G_Messungen_01.jpg|200px|thumb|right|Picture 2: Measuring system installed in the bottom of a drained lock chamber]]Standard measurements include the loading tests on piles and anchors as stipulated in the standards. Measurements are also carried out at slopes, retaining structures and foundations for the preservation of evidence and when using the observational method. Measurements at structures, foundation elements, in the ground and on models can be useful for design in cases where neither theoretical principles nor practical experience is available to provide reliable, economic solutions for geotechnical problems in waterways engineering.

== Measuring groundwater level and pressure ==

[[File:04_G_Messungen_02.jpg|200px|thumb|right|Picture 3: Sheet piling thickness being measured by a diver]]Geohydraulic measurements are needed both for ascertaining the existing groundwater conditions and for forecasting changes caused by work carried out in the federal waterways in the framework of planning approval procedures or hydrogeological expert opinions, for the conservation of groundwater evidence, for ascertaining groundwater pressure and current loads on concrete and earthwork structures or excavation pits, and for monitoring building structures.
[[Measuring groundwater level and pressure]]

== Geodynamic measurements ==

[[File:04_G_Messungen_03.jpg|200px|thumb|right|Picture 4: Measuring pendulum in Edertal dam]]Geodynamic measurements are used to ascertain the emission, propagation and impact of vibrations caused by construction work and operation at and on waterways. Vibrations in waterways are generated for example when installing sheet piling, during loosening and demolition blasting, during chiselling work, during surface and in-depth compaction of the ground, from propulsion systems of vessels, from vessel impact when mooring and from stationary systems such as pumps and machines, together with the flow forces, e.g. at locks.

== Measuring the thickness of sheet piles ==

Non-destructive methods using ultrasound equipment are carried out to assess the stability and serviceability of sheet piling structures. The measuring results are used to estimate the residual service life of existing structures (stability) and to forecast the point in time of the first signs of rust perforation (serviceability).

[https://www.youtube.com/watch?v=SACPZR_4ZCc Pfahlwanddickenmessung]
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back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Geotechnische Messungen]]

Geotechnical measurements

2022-05-20T11:07:43Z

BAWiki Glossar:

[[File:01_Methoden_01.jpg|200px|thumb|right|Picture 1: Vibration measurements at the bank]]Geotechnical measurements (static, dynamic, [[Hydraulics|hydraulic]]) serve on the one hand to monitor earthworks and structures after completion or during new construction work. On the other hand, they are indispensable when designing building structures on the basis of the observation method, when numerical predictions for various stages of construction progress are compared with real behaviour. It is thus possible to optimize the on-going computing steps.

== Geomechanical measurements ==
[[File:04_G_Messungen_01.jpg|200px|thumb|right|Picture 2: Measuring system installed in the bottom of a drained lock chamber]]Standard measurements include the loading tests on piles and anchors as stipulated in the standards. Measurements are also carried out at slopes, retaining structures and foundations for the preservation of evidence and when using the observational method. Measurements at structures, foundation elements, in the ground and on models can be useful for design in cases where neither theoretical principles nor practical experience is available to provide reliable, economic solutions for geotechnical problems in waterways engineering.

== Measuring groundwater level and pressure ==

[[File:04_G_Messungen_02.jpg|200px|thumb|right|Picture 3: Sheet piling thickness being measured by a diver]]Geohydraulic measurements are needed both for ascertaining the existing groundwater conditions and for forecasting changes caused by work carried out in the federal waterways in the framework of planning approval procedures or hydrogeological expert opinions, for the conservation of groundwater evidence, for ascertaining groundwater pressure and current loads on concrete and earthwork structures or excavation pits, and for monitoring building structures.
[[Measuring groundwater level and pressure]]

== Geodynamic measurements ==

[[File:04_G_Messungen_03.jpg|200px|thumb|right|Picture 4: Measuring pendulum in Edertal dam]]Geodynamic measurements are used to ascertain the emission, propagation and impact of vibrations caused by construction work and operation at and on waterways. Vibrations in waterways are generated for example when installing sheet piling, during loosening and demolition blasting, during chiselling work, during surface and in-depth compaction of the ground, from propulsion systems of vessels, from vessel impact when mooring and from stationary systems such as pumps and machines, together with the flow forces, e.g. at locks.

== Measuring the thickness of sheet piles ==

Non-destructive methods using ultrasound equipment are carried out to assess the stability and serviceability of sheet piling structures. The measuring results are used to estimate the residual service life of existing structures (stability) and to forecast the point in time of the first signs of rust perforation (serviceability).

[https://www.youtube.com/watch?v=SACPZR_4ZCc Pfahlwanddickenmessung]
----
back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Geotechnische Messungen]]

Geotechnical field tests

2022-05-20T10:43:47Z

BAWiki Glossar: /* Geophysical measurements */

Field tests include alongside direct ground explorations (borings and trial pits), indirect exploration methods using sounding apparatus, as well as geophysical and seismic measurements. The indirect methods make it possible to explore the condition of the ground while causing only minimum disturbance, if any, to the ground structure.

== Direct ground exploration ==

Direct ground exploration is usually contracted out to suitable companies while the Federal Waterways and Shipping Offices are responsible for supervision. Well drilling experts from BAW carry out random checks. In special cases, driven core sounding and hollow stem auger drilling is carried out by BAW staff.

== Indirect exploration methods ==

For indirect exploration, field tests are carried out partly by BAW and partly by external companies to obtain results that allow conclusions to be drawn about the structure of the ground and its properties. BAW uses the following geotechnical equipment and methods:

* Dynamic probing light (DHL)
* Dynamic probing heavy (DPH)
* (modified) standard penetration test (BDP)
* Cone penetration test (CPT)
* Flat dilatometer
* Air pressure probing
* Field vane test
* In-situ determination of density
* Freeze core sampling
* Plate Load test
* Dynamic plate load test

== Geophysical measurements ==

Geophysical measurements are used to establish soil [[Model|models]] or investigate geological and [[Anthropogen|anthropogenic]] disturbance zones and bodies. The appropriate deployment of geophysical methods depends on the presence of contrasts in the physical parameters of the ground (density, specific electrical resistance, dielectric constant, velocity of seismic waves, etc.)

The following methods are used:

* Geoelectric methods
* Seismic methods
* Georadar
* Borehole geophysical methods

== Geodynamic field tests ==

BAW has developed low-cost field tests and analysis procedures for replacing elaborate and expensive methods such as trial pile driving and trial detonations. These consist of:

* Simulating pile hammer
* Simulating vibratory driving
* Underwater trial detonations for simulation the vibrations caused by detonation for the demolition of structures under water

== Geohydraulic field tests ==

The use of different field test methods allows the geohydraulic properties of aquifers, e.g. their hydraulic conductivity or [[Specific storage coefficient|specific storage coefficients]], to be calculated and groundwater flow velocities to be recorded in situ. Depending on the boundary conditions of the specific site and the issues being investigated, the BAW will choose suitable techniques from a wide range of test methods, accompany the execution of the tests and evaluate the test results. Tests include:

* Pump tests for the calculation of the large-scale conductivity and storage properties of an aquifer,
* Hydraulic borehole tests (constant rate injection, drill-stem, slug-and-bail and water pressure tests) to calculate local conductivity and storage values in the vicinity of the borehole,
* (Thermal mass) flow meter measurements to find out preferential inflow zones in boreholes or near well screens,
* Thermal measurements to locate leaks in impervious canal bed linings,
* Tracer tests (introducing natural and artificial tracers into the aquifer) to plot groundwater flows,
* Groundwater sampling to calculate the concentrations of substances in the water.
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back to: [[Geotechnical Engineering Methods]]
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[[Overview]]
[[de:Geotechnische Feldversuche]]

Geotechnical field tests

2022-05-20T10:42:42Z

BAWiki Glossar: /* Geophysical measurements */

Field tests include alongside direct ground explorations (borings and trial pits), indirect exploration methods using sounding apparatus, as well as geophysical and seismic measurements. The indirect methods make it possible to explore the condition of the ground while causing only minimum disturbance, if any, to the ground structure.

== Direct ground exploration ==

Direct ground exploration is usually contracted out to suitable companies while the Federal Waterways and Shipping Offices are responsible for supervision. Well drilling experts from BAW carry out random checks. In special cases, driven core sounding and hollow stem auger drilling is carried out by BAW staff.

== Indirect exploration methods ==

For indirect exploration, field tests are carried out partly by BAW and partly by external companies to obtain results that allow conclusions to be drawn about the structure of the ground and its properties. BAW uses the following geotechnical equipment and methods:

* Dynamic probing light (DHL)
* Dynamic probing heavy (DPH)
* (modified) standard penetration test (BDP)
* Cone penetration test (CPT)
* Flat dilatometer
* Air pressure probing
* Field vane test
* In-situ determination of density
* Freeze core sampling
* Plate Load test
* Dynamic plate load test

== Geophysical measurements ==

Geophysical measurements are used to establish soil [[Model|models]] or investigate geological and anthropogenic disturbance zones and bodies. The appropriate deployment of geophysical methods depends on the presence of contrasts in the physical parameters of the ground (density, specific electrical resistance, dielectric constant, velocity of seismic waves, etc.)

The following methods are used:

* Geoelectric methods
* Seismic methods
* Georadar
* Borehole geophysical methods

== Geodynamic field tests ==

BAW has developed low-cost field tests and analysis procedures for replacing elaborate and expensive methods such as trial pile driving and trial detonations. These consist of:

* Simulating pile hammer
* Simulating vibratory driving
* Underwater trial detonations for simulation the vibrations caused by detonation for the demolition of structures under water

== Geohydraulic field tests ==

The use of different field test methods allows the geohydraulic properties of aquifers, e.g. their hydraulic conductivity or [[Specific storage coefficient|specific storage coefficients]], to be calculated and groundwater flow velocities to be recorded in situ. Depending on the boundary conditions of the specific site and the issues being investigated, the BAW will choose suitable techniques from a wide range of test methods, accompany the execution of the tests and evaluate the test results. Tests include:

* Pump tests for the calculation of the large-scale conductivity and storage properties of an aquifer,
* Hydraulic borehole tests (constant rate injection, drill-stem, slug-and-bail and water pressure tests) to calculate local conductivity and storage values in the vicinity of the borehole,
* (Thermal mass) flow meter measurements to find out preferential inflow zones in boreholes or near well screens,
* Thermal measurements to locate leaks in impervious canal bed linings,
* Tracer tests (introducing natural and artificial tracers into the aquifer) to plot groundwater flows,
* Groundwater sampling to calculate the concentrations of substances in the water.
----
back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Geotechnische Feldversuche]]

Geotechnical field tests

2022-05-20T10:39:16Z

BAWiki Glossar: /* Geohydraulic field tests */

Field tests include alongside direct ground explorations (borings and trial pits), indirect exploration methods using sounding apparatus, as well as geophysical and seismic measurements. The indirect methods make it possible to explore the condition of the ground while causing only minimum disturbance, if any, to the ground structure.

== Direct ground exploration ==

Direct ground exploration is usually contracted out to suitable companies while the Federal Waterways and Shipping Offices are responsible for supervision. Well drilling experts from BAW carry out random checks. In special cases, driven core sounding and hollow stem auger drilling is carried out by BAW staff.

== Indirect exploration methods ==

For indirect exploration, field tests are carried out partly by BAW and partly by external companies to obtain results that allow conclusions to be drawn about the structure of the ground and its properties. BAW uses the following geotechnical equipment and methods:

* Dynamic probing light (DHL)
* Dynamic probing heavy (DPH)
* (modified) standard penetration test (BDP)
* Cone penetration test (CPT)
* Flat dilatometer
* Air pressure probing
* Field vane test
* In-situ determination of density
* Freeze core sampling
* Plate Load test
* Dynamic plate load test

== Geophysical measurements ==

Geophysical measurements are used to establish soil models or investigate geological and anthropogenic disturbance zones and bodies. The appropriate deployment of geophysical methods depends on the presence of contrasts in the physical parameters of the ground (density, specific electrical resistance, dielectric constant, velocity of seismic waves, etc.)

The following methods are used:

* Geoelectric methods
* Seismic methods
* Georadar
* Borehole geophysical methods

== Geodynamic field tests ==

BAW has developed low-cost field tests and analysis procedures for replacing elaborate and expensive methods such as trial pile driving and trial detonations. These consist of:

* Simulating pile hammer
* Simulating vibratory driving
* Underwater trial detonations for simulation the vibrations caused by detonation for the demolition of structures under water

== Geohydraulic field tests ==

The use of different field test methods allows the geohydraulic properties of aquifers, e.g. their hydraulic conductivity or [[Specific storage coefficient|specific storage coefficients]], to be calculated and groundwater flow velocities to be recorded in situ. Depending on the boundary conditions of the specific site and the issues being investigated, the BAW will choose suitable techniques from a wide range of test methods, accompany the execution of the tests and evaluate the test results. Tests include:

* Pump tests for the calculation of the large-scale conductivity and storage properties of an aquifer,
* Hydraulic borehole tests (constant rate injection, drill-stem, slug-and-bail and water pressure tests) to calculate local conductivity and storage values in the vicinity of the borehole,
* (Thermal mass) flow meter measurements to find out preferential inflow zones in boreholes or near well screens,
* Thermal measurements to locate leaks in impervious canal bed linings,
* Tracer tests (introducing natural and artificial tracers into the aquifer) to plot groundwater flows,
* Groundwater sampling to calculate the concentrations of substances in the water.
----
back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Geotechnische Feldversuche]]

Analytical methods

2022-05-20T08:56:25Z

BAWiki Glossar:

[[File:05_Analytische_V_01.jpg|200px|thumb|right|Picture 1: Spring model for settlements]]Analytical methods applied in conventional geotechnical engineering are often to calculate the vertical displacements of the subsoil (settlement and heave) and the behaviour of soil in its ultimate limit state.

[[File:05_Analytische_V_02.jpg|200px|thumb|right|Picture 2: Earth pressure failure mechanisms]]
[[File:05_Analytische_V_03.jpg|200px|thumb|right|Picture 3: Ground failure diagram]]A well-known example is the concept of subgrade reaction approach which defines a bedding or subgrade reaction module to compute the interaction of the soil with the foundation plate. The approach is based on the assumption that the settlement is linearly dependent on the normal base pressure, whereupon the linear factor has the quality of a spring constant. The subgrade modulus can best be evaluated by assuming a simplified (linear) base pressure and performing a settlement calculation with then can be corrected iteratively. Despite these simplifications, the method offered for a long time the only available solution to deal with interaction analyses. Nowadays [[Numerical Methods|numerical methods]] are a readily available and a better way to calculate deformations for serviceability limit state design and to map the interaction between a structure and the soil. Analytical methods can also be used to observe time-dependent processes such as consolidation settlement and creep of fine-grained clayey and silty soils.

Analysis of ultimate limit state comprises calculation of active or passive earth pressure which occurs when a wall is pushed against or moves away from the backfill, bearing resistance or punching failure of a foundation loaded by an excessive load or the loss of overall slope stability. Corresponding tasks are then defined by calculating the safety factor against ultimate limit state or failure of structural elements. The corresponding calculation methods are governed by standards.

[[File:05_Analytische_V_04.jpg|200px|thumb|right|Picture 4: Embankment failure diagram]]The analytical methods for monitoring ultimate limit states are based on calculating the applicable load capacity (collapse load), which is done using collapse theorems from plasto-mechanics. The static or lower bound theorem states that a body will not fail if there is (at least) one permitted stress-field that fulfils the boundary and equilibrium conditions. The kinematic or upper bound theorem states that a base will collapse if there is a failure mechanism by which the external forces exceed the internal work being done to overcome the shear strength. Given that solutions based on the lower bound theorem limit the load capacity from the bottom up, the error is usually kept on the safe side. The kinematic theorem is used in the vast majority of actual cases as it is easier to apply. This involves studying an adequate number of kinematically feasible (rigid-plastic) failure mechanisms and thus determining which of these offers the least factor of safety.

Analytical methods for calculating groundwater flows are described on the following page.

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[[Analytical methods – Groundwater flow]]
----
back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Analytische Verfahren]]

Structural Engineering Methods

2022-04-01T11:48:02Z

BAWiki Glossar:

[[de:Bautechnische Methoden]]
[[File:01_Bautechnische_Methoden_01.jpg|200px|thumb|right|Procedure of an expertise]]
The Department of Structural Engineering makes use of numerical, testing and experimental methods. The purpose of these calculation methods is to provide the most realistic possible assessments of actions, structural elements or structures. Trials and laboratory analyses, partly based on test procedures developed by the BAW, help to make realistic assessments of actions, construction materials or the resistance of structural elements. Theoretical research work paves the way for experimental procedures.
* [[Alkali Reactivity of Aggregates and Concretes]]
* [[Analysis and Testing of Construction and Coating Materials]]
* [[Durability tests for rebar corrosion]]
* [[Assessing the Freeze-Thaw Resistance of Concrete]]
* [[Development of Hydration Heat in Concrete]]
* [[Corrosion protection tests (steel structures and corrosion protection)]]
* [[Nonlinear structural engineering analysis (NiTrA)]]
* [[Protecting offshore wind turbines against corrosion]]
* [[Non-linear probabilistic calculations]]
* [[Shear strength of concrete and masonry]]
* [[Assessing the load-bearing capacity of closures on existing hydraulic steel structures (steel structures and corrosion protection)]]
* [[Evaluating the condition of solid structures]]
* [[Condition forecast]]

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back to: [[Main Page]]

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[[Overview]]

Main Page

2022-04-01T11:46:55Z

BAWiki Glossar:

==BAWiki==

* [[Hydraulic Engineering Methods]]
*# [[Mathematical Methods]]
*# [[Field Study Measurements]]
*# [[Ship Handling Simulation]]
*# [[Hydraulic Modelling]]
* Hydraulic Engineering Topics
*# Weir Constructions
*# [[Ecological Connectivity]]
*# [[Tidal Dynamics of Estuaries]]

* [[Structural Engineering Methods]]
*# [[Alkali Reactivity of Aggregates and Concretes]]
*# [[Analysis and Testing of Construction and Coating Materials]]
*# [[Durability tests for rebar corrosion]]
*# [[Assessing the Freeze-Thaw Resistance of Concrete]]
*# [[Development of Hydration Heat in Concrete]]
*# [[Corrosion protection tests (steel structures and corrosion protection)]]
*# [[Nonlinear structural engineering analysis (NiTrA)]]
*# [[Protecting offshore wind turbines against corrosion]]
*# [[Non-linear probabilistic calculations]]
*# [[Shear strength of concrete and masonry]]
*# [[Assessing the load-bearing capacity of closures on existing hydraulic steel structures (steel structures and corrosion protection)]]
*# [[Evaluating the condition of solid structures]]
*# [[Condition forecast]]

* [[Geotechnical Engineering Methods]]
*# [[Geotechnical laboratory testing]]
*# [[Geotechnical field tests]]
*# [[Geotechnical measurements]]
*# [[Analytical methods]]
*# [[Numerical Methods]]

* BAWiki: [[Overview|Quick Access]] to all topics
* BAWiki: Access according to [[Special:Categories|Categories]]
* BAWiki: [[:Category:Glossary|Glossary]]
[[de:Hauptseite]]

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Analytical methods – Groundwater flow

2022-04-01T11:35:08Z

BAWiki Glossar:

A wide range of analytical solutions are available for calculating groundwater flow. These generally consist of one-dimensional mathematical-physical models with highly simplified model assumptions. Even so, in many cases analytical solutions are capable of describing groundwater flow problems with adequate accuracy. Examples include steady state, vertical-plane inflow to a ditch and steady state rotationally symmetrical inflow to a well under varying boundary conditions both for confined and unconfined flow based on the Dupuit assumptions. Groundwater seepage at excavation pits can be calculated for simple geometric situations and boundary conditions by superposition of well flows based on the multi-well equation by Forchheimer. Solutions for transient flows are available both for inflow to pits and for well flow. The best known is Theis' well formula which is also used in the evaluation of pump tests. A compilation of analytical solutions for groundwater flow problems along with explanations of the basic assumptions and the mathematical derivations is provided e.g. by Odenwald et al. (2018).
<gallery>
File:08_Grundwasserstroemung_01.jpg|Picture 1: Dam undercurrent in a semi-confined aquifer
File:08_Grundwasserstroemung_02.jpg|Picture 2: Multi-well system in an unconfined aquifer
File:08_Grundwasserstroemung_03.jpg|Picture 3: Well inflow in an unconfined aquifer
File:08_Grundwasserstroemung_04.jpg|picture 4: Groundwater potential assuming a constant extraction rate from the well and confined groundwater flow
</gallery>

=== Literature ===

Odenwald, B.; Hekel, U.; Thormann, H.: Kap. 9: Grundwasserströmung – Grundwasserhaltung. In: Witt, K.J. (Hrsg.): Grundbau-Taschenbuch, 8. Auflage, Teil 2: Geotechnische Verfahren, S. 635 - 819, Ernst & Sohn, Berlin, 2018.

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back to: [[Analytical methods]]
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[[Overview]]

[[de:Analytische Verfahren - Grundwasserströmung]]

Interaction of ground and building structure

2022-03-25T10:01:12Z

BAWiki Glossar:

[[File:06_Numerische_V_02.jpg|200px|thumb|right|Picture 1: 3D model of the excavation pit for Sülfeld lock]]Deformation and stability calculations for building structures used in waterways engineering are increasingly carried out using the finite element method (FEM) and in recent years also the distinct element method (DEM). The advantage of FEM is that it can be used to visualize complex geometries and ground conditions, and also indicates interaction between building structure and the ground.

[[File:10_Wechselwirkung_B_B_01.jpg|200px|thumb|right|Picture 2: Deformed 2D model of Minden lock (river Weser)]]The aforementioned advantages of the method play an important role particularly in view of the increasing complexity of construction work, for example when building excavation pits right next to structures that are susceptible to deformation during the construction of new structures next to existing locks while the waterway continues normal shipping operations, or during subsequent calculation of load-bearing and deformation behaviour of existing building structures.

[[File:10_Wechselwirkung_B_B_02.jpg|200px|thumb|right|Picture 3: Ension settlement curves from the oedometer test and subsequent FEM calculation]]
[[File:10_Wechselwirkung_B_B_03.jpg|200px|thumb|right|Picture 4: DEM simulation of armourstones ]]Depending on requirements, 2D or 3D models are designed to solve the geotechnical problem. Various different material models are available for describing the mechanical behaviour of the soil. The necessary soil characteristics can be calibrated with the results from field tests, geotechnical measurements und laboratory tests for example by numerical simulation of an oedometer experiment. Realistic computation results are obtained by visualising the complete load history of the system consisting of building structure and ground, i.e. the sequence of construction phases and conditions that are planned for implementation of the construction work. This also takes account of the changing general hydraulic conditions. Attempts are also increasingly being made to ensure that the modelling phase also takes account of the effects resulting from production of the geotechnical structures (e.g. piles, subterraneous curtains).

DEM offers the possibility of overcoming the limits of FEM when it comes to large net deformation when dealing with geometric bodies such as boulders or spheres. In many cases, the calculations can be simplified by concentrating on spherical shapes which are then put together to generate other geometries such as polygonal armourstones.
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back to: [[Numerical Methods]]
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[[Overview]]
[[de:Wechselwirkung Boden-Bauwerk]]

Interaction of ground and building structure

2022-03-25T09:59:56Z

BAWiki Glossar: Created page with "Picture 1: 3D model of the excavation pit for Sülfeld lockDeformation and stability calculations for building structures use..."

[[File:06_Numerische_V_02.jpg|200px|thumb|right|Picture 1: 3D model of the excavation pit for Sülfeld lock]]Deformation and stability calculations for building structures used in waterways engineering are increasingly carried out using the finite element method (FEM) and in recent years also the distinct element method (DEM). The advantage of FEM is that it can be used to visualize complex geometries and ground conditions, and also indicates interaction between building structure and the ground.

[[File:10_Wechselwirkung_B_B_01.jpg|200px|thumb|right|Picture 2: Deformed 2D model of Minden lock (river Weser)]]The aforementioned advantages of the method play an important role particularly in view of the increasing complexity of construction work, for example when building excavation pits right next to structures that are susceptible to deformation during the construction of new structures next to existing locks while the waterway continues normal shipping operations, or during subsequent calculation of load-bearing and deformation behaviour of existing building structures.

[[File:10_Wechselwirkung_B_B_02.jpg|200px|thumb|right|Picture 3: Ension settlement curves from the oedometer test and subsequent FEM calculation]]
[[File:10_Wechselwirkung_B_B_03.jpg|200px|thumb|right|Picture 4: DEM simulation of armourstones ]]Depending on requirements, 2D or 3D models are designed to solve the geotechnical problem. Various different material models are available for describing the mechanical behaviour of the soil. The necessary soil characteristics can be calibrated with the results from field tests, geotechnical measurements und laboratory tests for example by numerical simulation of an oedometer experiment. Realistic computation results are obtained by visualising the complete load history of the system consisting of building structure and ground, i.e. the sequence of construction phases and conditions that are planned for implementation of the construction work. This also takes account of the changing general hydraulic conditions. Attempts are also increasingly being made to ensure that the modelling phase also takes account of the effects resulting from production of the geotechnical structures (e.g. piles, subterraneous curtains).

DEM offers the possibility of overcoming the limits of FEM when it comes to large net deformation when dealing with geometric bodies such as boulders or spheres. In many cases, the calculations can be simplified by concentrating on spherical shapes which are then put together to generate other geometries such as polygonal armourstones.
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back to: [[Geotechnical Engineering Methods]]
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[[Overview]]
[[de:Wechselwirkung Boden-Bauwerk]]

Groundwater models

2022-03-25T09:53:01Z

BAWiki Glossar: Created page with "Picture 1: Groundwater model for retention area weir, Kehl File:08_Grundwasserstroemung_02.jpg|200px|thumb|right|Pi..."

[[File:08_Grundwasserstroemung_01.jpg|200px|thumb|right|Picture 1: Groundwater model for retention area weir, Kehl]]
[[File:08_Grundwasserstroemung_02.jpg|200px|thumb|right|Picture 2: Transient dam saturation caused by a leak in the canal lining]]The basis for calculating groundwater and seepage flows is their description using mathematical models. Numerical computational methods based on the finite element method (FEM) or the finite difference method (FDM) offer a suitable range of instruments for dealing with complex geohydraulic issues. These computational models enable the spatial variability of the ground and external inflows as well as the change in the water saturation conditions to be taken into account. Computational groundwater flow models are used to investigate a wide range of issues, including:

* to determine the impact of construction measures in waterways on the large-scale groundwater conditions,
* to search for alternatives for minimising unwanted impacts of construction measures on the existing groundwater system,
* to ascertain the forces resulting from groundwater flow on the ground and on the structure and
* to compare suitable groundwater drainage or relief measures for reducing unwanted groundwater effects.

[[File:08_Grundwasserstroemung_03.jpg|200px|thumb|right|Picture 3: Groundwater model for the excavation pit for Minden lock]]The use of numerical groundwater models can entail differing levels of spatial resolution (one-dimensional, two-dimensional along a horizontal or vertical plane, three-dimensional) and complexity (steady-state/transient, saturated/unsaturated), depending on the specific issue and on the available data.

[[File:08_Grundwasserstroemung_04.jpg|200px|thumb|right|Picture 4: Groundwater model (quarter model) for a dam with culvert structure]]Vertical-plane calculations are suitable for groundwater flows that occur with elongated building structures with largely unchanging hydraulic boundary conditions and presumably negligible flow normal to the computational plane (e.g. flow through a canal or river embankment). In the case of flows with a free groundwater surface where the part of the model domain which is saturated with water is not known in advance or changes during the time period observed, a saturated/unsaturated numerical flow calculation is carried out (e.g. to determine the impact of floods or rapid water level fluctuations on the flow through an embankment). In the unsaturated zone, the functional interrelationship between pore water pressure, degree of saturation and hydraulic conductivity must be taken into account. Given that these relationships of soil hydraulics are non-linear, the numerical calculation requires much more time and effort than in the case of completely water-saturated flows.

3D numerical calculation of the groundwater flow is required if the geometric situation or the hydraulic boundary conditions result in a pronounced 3D flow field that cannot be represented adequately by simplified groundwater models. This is usually the case, for example, with groundwater modelling of flows around a building structure to determine the forces resulting from groundwater pressure and flow. Three-dimensional modelling, particularly when taking account of saturated/unsaturated flows, requires an in-depth knowledge of geohydraulics and the relevant numerical computational methods, together with extensive experience in modelling.

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back to: [[Numerical Methods]]
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[[Overview]]
[[de:Grundwassermodelle]]

Numerical Methods

2022-03-25T09:46:20Z

BAWiki Glossar: Created page with "== Groundwater models == Picture 1: Groundwater model for the excavation pit for Minden lockBasis for the calculation of gro..."

== Groundwater models ==

[[File:06_Numerische_V_01.jpg|200px|thumb|right|Picture 1: Groundwater model for the excavation pit for Minden lock]]Basis for the calculation of groundwater flow is its description using mathematical models. Numerical computational methods based on the finite element method (FEM) or the finite difference method (FDM) meanwhile offer a suitable range of standard instruments for dealing with complex geohydraulic issues.
[[Groundwater models]]

== Interaction of ground and building structure ==

[[File:06_Numerische_V_02.jpg|200px|thumb|right|Picture 2: 3D model of the excavation pit for Sülfeld lock]]Deformation and stability calculations for building structures used in waterways engineering are increasingly carried out using the finite element method (FEM) and in recent years also the distinct element method (DEM). The advantage of FEM is that it can be used to visualize complex geometries and ground conditions, and also indicates interaction between building structure and the ground.
[[Interaction of ground and building structure]]
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back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Numerische Verfahren]]

Analytical methods – Groundwater flow

2022-03-25T09:40:54Z

BAWiki Glossar: Created page with "A wide range of analytical solutions are available for calculating groundwater flow. These generally consist of one-dimensional mathematical-physical models with highly simpli..."

A wide range of analytical solutions are available for calculating groundwater flow. These generally consist of one-dimensional mathematical-physical models with highly simplified model assumptions. Even so, in many cases analytical solutions are capable of describing groundwater flow problems with adequate accuracy. Examples include steady state, vertical-plane inflow to a ditch and steady state rotationally symmetrical inflow to a well under varying boundary conditions both for confined and unconfined flow based on the Dupuit assumptions. Groundwater seepage at excavation pits can be calculated for simple geometric situations and boundary conditions by superposition of well flows based on the multi-well equation by Forchheimer. Solutions for transient flows are available both for inflow to pits and for well flow. The best known is Theis' well formula which is also used in the evaluation of pump tests. A compilation of analytical solutions for groundwater flow problems along with explanations of the basic assumptions and the mathematical derivations is provided e.g. by Odenwald et al. (2018).

=== Literature ===

Odenwald, B.; Hekel, U.; Thormann, H.: Kap. 9: Grundwasserströmung – Grundwasserhaltung. In: Witt, K.J. (Hrsg.): Grundbau-Taschenbuch, 8. Auflage, Teil 2: Geotechnische Verfahren, S. 635 - 819, Ernst & Sohn, Berlin, 2018.

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back to: [[Analytical methods]]
----
[[Overview]]

Analytical methods

2022-03-25T09:33:59Z

BAWiki Glossar:

[[File:05_Analytische_V_01.jpg|200px|thumb|right|Picture 1: Spring model for settlements]]Analytical methods applied in conventional geotechnical engineering are often to calculate the vertical displacements of the subsoil (settlement and heave) and the behaviour of soil in its ultimate limit state.

[[File:05_Analytische_V_02.jpg|200px|thumb|right|Picture 2: Earth pressure failure mechanisms]]
[[File:05_Analytische_V_03.jpg|200px|thumb|right|Picture 3: Ground failure diagram]]A well-known example is the concept of subgrade reaction approach which defines a bedding or subgrade reaction module to compute the interaction of the soil with the foundation plate. The approach is based on the assumption that the settlement is linearly dependent on the normal base pressure, whereupon the linear factor has the quality of a spring constant. The subgrade modulus can best be evaluated by assuming a simplified (linear) base pressure and performing a settlement calculation with then can be corrected iteratively. Despite these simplifications, the method offered for a long time the only available solution to deal with interaction analyses. Nowadays numerical methods are a readily available and a better way to calculate deformations for serviceability limit state design and to map the interaction between a structure and the soil. Analytical methods can also be used to observe time-dependent processes such as consolidation settlement and creep of fine-grained clayey and silty soils.

Analysis of ultimate limit state comprises calculation of active or passive earth pressure which occurs when a wall is pushed against or moves away from the backfill, bearing resistance or punching failure of a foundation loaded by an excessive load or the loss of overall slope stability. Corresponding tasks are then defined by calculating the safety factor against ultimate limit state or failure of structural elements. The corresponding calculation methods are governed by standards.

[[File:05_Analytische_V_04.jpg|200px|thumb|right|Picture 4: Embankment failure diagram]]The analytical methods for monitoring ultimate limit states are based on calculating the applicable load capacity (collapse load), which is done using collapse theorems from plasto-mechanics. The static or lower bound theorem states that a body will not fail if there is (at least) one permitted stress-field that fulfils the boundary and equilibrium conditions. The kinematic or upper bound theorem states that a base will collapse if there is a failure mechanism by which the external forces exceed the internal work being done to overcome the shear strength. Given that solutions based on the lower bound theorem limit the load capacity from the bottom up, the error is usually kept on the safe side. The kinematic theorem is used in the vast majority of actual cases as it is easier to apply. This involves studying an adequate number of kinematically feasible (rigid-plastic) failure mechanisms and thus determining which of these offers the least factor of safety.

Analytical methods for calculating groundwater flows are described on the following page.

----
[[Analytical methods – Groundwater flow]]
----
back to: [[Geotechnical Engineering Methods]]
----
[[Overview]]
[[de:Analytische Verfahren]]

Analytical methods

2022-03-25T09:33:25Z

BAWiki Glossar: Created page with "Picture 1: Spring model for settlementsAnalytical methods applied in conventional geotechnical engineering are often to calc..."

[[File:05_Analytische_V_01.jpg|200px|thumb|right|Picture 1: Spring model for settlements]]Analytical methods applied in conventional geotechnical engineering are often to calculate the vertical displacements of the subsoil (settlement and heave) and the behaviour of soil in its ultimate limit state.

[[File:05_Analytische_V_02.jpg|200px|thumb|right|Picture 2: Earth pressure failure mechanisms]]
[[File:05_Analytische_V_03.jpg|200px|thumb|right|Picture 3: Ground failure diagram]]A well-known example is the concept of subgrade reaction approach which defines a bedding or subgrade reaction module to compute the interaction of the soil with the foundation plate. The approach is based on the assumption that the settlement is linearly dependent on the normal base pressure, whereupon the linear factor has the quality of a spring constant. The subgrade modulus can best be evaluated by assuming a simplified (linear) base pressure and performing a settlement calculation with then can be corrected iteratively. Despite these simplifications, the method offered for a long time the only available solution to deal with interaction analyses. Nowadays numerical methods are a readily available and a better way to calculate deformations for serviceability limit state design and to map the interaction between a structure and the soil. Analytical methods can also be used to observe time-dependent processes such as consolidation settlement and creep of fine-grained clayey and silty soils.

Analysis of ultimate limit state comprises calculation of active or passive earth pressure which occurs when a wall is pushed against or moves away from the backfill, bearing resistance or punching failure of a foundation loaded by an excessive load or the loss of overall slope stability. Corresponding tasks are then defined by calculating the safety factor against ultimate limit state or failure of structural elements. The corresponding calculation methods are governed by standards.

[[Datei:05_Analytische_V_04.jpg|200px|thumb|right|Picture 4: Embankment failure diagram]]The analytical methods for monitoring ultimate limit states are based on calculating the applicable load capacity (collapse load), which is done using collapse theorems from plasto-mechanics. The static or lower bound theorem states that a body will not fail if there is (at least) one permitted stress-field that fulfils the boundary and equilibrium conditions. The kinematic or upper bound theorem states that a base will collapse if there is a failure mechanism by which the external forces exceed the internal work being done to overcome the shear strength. Given that solutions based on the lower bound theorem limit the load capacity from the bottom up, the error is usually kept on the safe side. The kinematic theorem is used in the vast majority of actual cases as it is easier to apply. This involves studying an adequate number of kinematically feasible (rigid-plastic) failure mechanisms and thus determining which of these offers the least factor of safety.

Analytical methods for calculating groundwater flows are described on the following page.

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[[Analytical methods – Groundwater flow]]
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[[de:Analytische Verfahren]]

Measuring groundwater level and pressure

2022-03-25T09:29:03Z

BAWiki Glossar:

[[File:04_G_Messungen_01.jpg|200px|thumb|right|Measuring system installed in the bottom of a drained lock chamber]]Groundwater level and pressure are measured in order to assess the groundwater conditions in the vicinity of the federal waterways. These measurements form the basis for predicting changes to groundwater conditions caused by construction measures within the framework of hydrogeological expert reports, for determining groundwater pressure and flow actions on concrete and earthwork structures or excavation pits, for collecting groundwater evidence and for monitoring the groundwater around structures.

Groundwater level and pressure measurements can be taken in open or closed groundwater observation wells. Open groundwater observation wells are used for soils or rock with medium to high hydraulic conductivity. They consist of a filter and a standpipe that extends to the ground surface and that enables atmospheric pressure to be compensated for. In open groundwater observation wells, the water level in the standpipe is measured either manually using a light plummet or automatically by means of a pressure transducer in the standpipe, with the measurements being stored on a data logger. However, they are only of limited use when it comes to measuring rapid changes of pore water pressure in less permeable soils or rock, in which case closed groundwater observation wells are used. These consist of a pressure transducer surrounded by a sealed filter zone, which is fitted directly into the ground. The measured data are recorded by a data logger installed on the ground surface.

BAW creates detailed project-specific guidelines for the selection and development of the groundwater measuring system together with appropriate procedures in accordance with local conditions and the necessary data. It monitors the preparation of the measuring wells and the installation of the measuring technology and analyses the measurements. Specific measurement systems are developed for particular requirements (e.g. measuring groundwater pressure under weirs and lock beds).

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[[de:Grundwasserstands- und -druckmessungen]]

Measuring groundwater level and pressure

2022-03-25T09:28:07Z

BAWiki Glossar: Created page with "Measuring system installed in the bottom of a drained lock chamberGroundwater level and pressure are measured in order to asse..."

[[File:04_G_Messungen_01.jpg|200px|thumb|right|Measuring system installed in the bottom of a drained lock chamber]]Groundwater level and pressure are measured in order to assess the groundwater conditions in the vicinity of the federal waterways. These measurements form the basis for predicting changes to groundwater conditions caused by construction measures within the framework of hydrogeological expert reports, for determining groundwater pressure and flow actions on concrete and earthwork structures or excavation pits, for collecting groundwater evidence and for monitoring the groundwater around structures.

Groundwater level and pressure measurements can be taken in open or closed groundwater observation wells. Open groundwater observation wells are used for soils or rock with medium to high hydraulic conductivity. They consist of a filter and a standpipe that extends to the ground surface and that enables atmospheric pressure to be compensated for. In open groundwater observation wells, the water level in the standpipe is measured either manually using a light plummet or automatically by means of a pressure transducer in the standpipe, with the measurements being stored on a data logger. However, they are only of limited use when it comes to measuring rapid changes of pore water pressure in less permeable soils or rock, in which case closed groundwater observation wells are used. These consist of a pressure transducer surrounded by a sealed filter zone, which is fitted directly into the ground. The measured data are recorded by a data logger installed on the ground surface.

BAW creates detailed project-specific guidelines for the selection and development of the groundwater measuring system together with appropriate procedures in accordance with local conditions and the necessary data. It monitors the preparation of the measuring wells and the installation of the measuring technology and analyses the measurements. Specific measurement systems are developed for particular requirements (e.g. measuring groundwater pressure under weirs and lock beds).

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[[de:Grundwasserstands- und -druckmessungen]]

Geotechnical measurements

2022-03-25T09:22:49Z

BAWiki Glossar: Created page with "Picture 1: Vibration measurements at the bankGeotechnical measurements (static, dynamic, hydraulic) serve on the one hand to moni..."

[[File:01_Methoden_01.jpg|200px|thumb|right|Picture 1: Vibration measurements at the bank]]Geotechnical measurements (static, dynamic, hydraulic) serve on the one hand to monitor earthworks and structures after completion or during new construction work. On the other hand, they are indispensable when designing building structures on the basis of the observation method, when numerical predictions for various stages of construction progress are compared with real behaviour. It is thus possible to optimize the on-going computing steps.

== Geomechanical measurements ==
[[File:04_G_Messungen_01.jpg|200px|thumb|right|Picture 2: Measuring system installed in the bottom of a drained lock chamber]]Standard measurements include the loading tests on piles and anchors as stipulated in the standards. Measurements are also carried out at slopes, retaining structures and foundations for the preservation of evidence and when using the observational method. Measurements at structures, foundation elements, in the ground and on models can be useful for design in cases where neither theoretical principles nor practical experience is available to provide reliable, economic solutions for geotechnical problems in waterways engineering.

== Measuring groundwater level and pressure ==

[[File:04_G_Messungen_02.jpg|200px|thumb|right|Picture 3: Sheet piling thickness being measured by a diver]]Geohydraulic measurements are needed both for ascertaining the existing groundwater conditions and for forecasting changes caused by work carried out in the federal waterways in the framework of planning approval procedures or hydrogeological expert opinions, for the conservation of groundwater evidence, for ascertaining groundwater pressure and current loads on concrete and earthwork structures or excavation pits, and for monitoring building structures.
[[Measuring groundwater level and pressure]]

== Geodynamic measurements ==

[[File:04_G_Messungen_03.jpg|200px|thumb|right|Picture 4: Measuring pendulum in Edertal dam]]Geodynamic measurements are used to ascertain the emission, propagation and impact of vibrations caused by construction work and operation at and on waterways. Vibrations in waterways are generated for example when installing sheet piling, during loosening and demolition blasting, during chiselling work, during surface and in-depth compaction of the ground, from propulsion systems of vessels, from vessel impact when mooring and from stationary systems such as pumps and machines, together with the flow forces, e.g. at locks.

== Measuring the thickness of sheet piles ==

Non-destructive methods using ultrasound equipment are carried out to assess the stability and serviceability of sheet piling structures. The measuring results are used to estimate the residual service life of existing structures (stability) and to forecast the point in time of the first signs of rust perforation (serviceability).

[https://www.youtube.com/watch?v=SACPZR_4ZCc Pfahlwanddickenmessung]
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[[de:Geotechnische Messungen]]

Geotechnical field tests

2022-03-25T09:07:32Z

BAWiki Glossar: Created page with "Field tests include alongside direct ground explorations (borings and trial pits), indirect exploration methods using sounding apparatus, as well as geophysical and seismic me..."

Field tests include alongside direct ground explorations (borings and trial pits), indirect exploration methods using sounding apparatus, as well as geophysical and seismic measurements. The indirect methods make it possible to explore the condition of the ground while causing only minimum disturbance, if any, to the ground structure.

== Direct ground exploration ==

Direct ground exploration is usually contracted out to suitable companies while the Federal Waterways and Shipping Offices are responsible for supervision. Well drilling experts from BAW carry out random checks. In special cases, driven core sounding and hollow stem auger drilling is carried out by BAW staff.

== Indirect exploration methods ==

For indirect exploration, field tests are carried out partly by BAW and partly by external companies to obtain results that allow conclusions to be drawn about the structure of the ground and its properties. BAW uses the following geotechnical equipment and methods:

* Dynamic probing light (DHL)
* Dynamic probing heavy (DPH)
* (modified) standard penetration test (BDP)
* Cone penetration test (CPT)
* Flat dilatometer
* Air pressure probing
* Field vane test
* In-situ determination of density
* Freeze core sampling
* Plate Load test
* Dynamic plate load test

== Geophysical measurements ==

Geophysical measurements are used to establish soil models or investigate geological and anthropogenic disturbance zones and bodies. The appropriate deployment of geophysical methods depends on the presence of contrasts in the physical parameters of the ground (density, specific electrical resistance, dielectric constant, velocity of seismic waves, etc.)

The following methods are used:

* Geoelectric methods
* Seismic methods
* Georadar
* Borehole geophysical methods

== Geodynamic field tests ==

BAW has developed low-cost field tests and analysis procedures for replacing elaborate and expensive methods such as trial pile driving and trial detonations. These consist of:

* Simulating pile hammer
* Simulating vibratory driving
* Underwater trial detonations for simulation the vibrations caused by detonation for the demolition of structures under water

== Geohydraulic field tests ==

The use of different field test methods allows the geohydraulic properties of aquifers, e.g. their hydraulic conductivity or specific storage coefficients, to be calculated and groundwater flow velocities to be recorded in situ. Depending on the boundary conditions of the specific site and the issues being investigated, the BAW will choose suitable techniques from a wide range of test methods, accompany the execution of the tests and evaluate the test results. Tests include:

* Pump tests for the calculation of the large-scale conductivity and storage properties of an aquifer,
* Hydraulic borehole tests (constant rate injection, drill-stem, slug-and-bail and water pressure tests) to calculate local conductivity and storage values in the vicinity of the borehole,
* (Thermal mass) flow meter measurements to find out preferential inflow zones in boreholes or near well screens,
* Thermal measurements to locate leaks in impervious canal bed linings,
* Tracer tests (introducing natural and artificial tracers into the aquifer) to plot groundwater flows,
* Groundwater sampling to calculate the concentrations of substances in the water.
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[[de:Geotechnische Feldversuche]]

Geotechnical laboratory testing

2022-03-25T09:02:18Z

BAWiki Glossar:

Geotechnical laboratory experiments are carried out on disturbed and undisturbed soil and rock samples. After sampling, the specimens are initially identified, described and classified according to EN ISO 14688 and further tests are stipulated/appointed.
== Sample preparation ==

* On delivery, the soil and rock specimens are initially sorted and catalogued.
* Plastic liners are cut open using a special machine.
* All specimens are photographed.
* The specimens are presented for soil identification by the expert. Sub-specimens are taken for further examination in the geotechnical laboratory.
* These are given lab numbers, then packed correctly and taken into intermediate storage.

== Classification tests ==

These geotechnical tests classify the soils and form the basis for further investigations:

* Grain size distribution
* Bulk density
* Grain density
* Water content
* Liquid limit
* Plastic limit
* Shrinkage limit
* Lime content
* Ignition loss

== Tests of the deformation behaviour ==

In order to estimate the deformation behaviour of the soil under load, laboratory tests can be carried out to obtain the necessary parameters. The degree to which these can be transferred to the in-situ conditions depends to a great extent on adequate simulation of the in-situ conditions during the test. It is therefore always advisable to carry out in-situ measurements as well.

* Compression test (oedometer)
* Triaxial deformation test

== Determination of soil and rock strength ==

Strength of soil and rock is an essential parameter for geotechnical verifications. It is significantly influenced by the water content which in consequence has to be considered with every test evaluation.

* Pocket and laboratory penetrometer
* Laboratory vane test
* Angle of repose
* Uniaxial compression test
* Direct shear test
* Simple shear test
* Ring shear test
* Triaxial shear test

== Water and Ground ==

The interaction of water and soil or rock affects significantly the ultimate limit state and the serviceability limit state. This requires a number of additional tests according to the actual requirements besides the determination of the water content (classification test).

* Water absorption
* Hydraulic conductivity
* Capillary rise
* Erosion test (modified pinhole test)
* Reversing flow permeameter
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[[de:Geotechnische Laborversuche]]

Geotechnical laboratory testing

2022-03-25T09:01:53Z

BAWiki Glossar: Created page with "Geotechnical laboratory experiments are carried out on disturbed and undisturbed soil and rock samples. After sampling, the specimens are initially identified, described and c..."

Geotechnical Engineering Methods

2022-03-25T08:57:46Z

BAWiki Glossar:

Methods in geotechnical engineering encompass experiments, measurements and calculations. The experiments are devided into laboratory experiments and field tests. Geotechnical calculations are carried out using (classical) analytical or numerical methods. A particular development is the "GBB Soft" code. This is a computing system that is particularly suitable for dimensioning embankment and bed protection measures.
<gallery>
File:01_Methoden_01.jpg|Picture 1: Calculation model diagrams
File:01_Methoden_02.jpg|Picture 2: Vibration measurements at the bank
File:01_Methoden_03.jpg|Picture 3: Vane shear test unit
File:01_Methoden_04.jpg|Picture 4: Triaxial test rig
File:01_Methoden_05.jpg|Picture 5: FE net Uelzen lock
</gallery>

*[[Geotechnical laboratory testing]]
*[[Geotechnical field tests]]
*[[Geotechnical measurements]]
*[[Analytical methods]]
*[[Numerical Methods]]

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[[de:Geotechnische Methoden]]

Geotechnical Engineering Methods

2022-03-25T08:53:32Z

BAWiki Glossar: Created page with "Methods in geotechnical engineering encompass experiments, measurements and calculations. The experiments are devided into laboratory experiments and field tests. Geotechnical..."

Condition forecast

2022-03-25T08:42:00Z

BAWiki Glossar:

[[File:14_Zustand_Prognose_01.jpg|200px|thumb|right|Picture 1: Typical gradient of a Herz curve]]In principle, each ageing structure is characterized by an ageing curve that describes the change in condition over time. The Herz function, due to its flexibility, is particularly suitable for representing the ageing of infrastructure elements and their components. Figure 1 shows the curve of a Herz function with a resistance period at the beginning where no ageing effect is observed. The function also allows describing very old structures.

The ageing process undergone by steel structures differs from that observed in solid structures or equipment. It is therefore necessary to obtain different ageing functions. To define the parameters of the functions, the Project Group Asset Management System conducted a Delphi interview. Based on this Delphi interview it was possible to systematically collect the expert knowledge available at the WSV and the BAW. As a result, ageing functions were obtained for different types of components in hydraulic structures. These functions can now be used to assess the current and future sub-ratings of the different components depending on their respective age, if no knowledge on damages is available.

A failure rate can be derived from the ageing function which can be used to define a Markov matrix. The Markov matrix describes the probability whether, for a specific time increment, a damage is assigned to another damage category (damage is getting worse) or whether it remains within the same category. The method is highly suitable for forecasting the progress of recognized damages. The BAW has defined 14 deterioration processes for describing the substantial damages occurring in waterway structures.

[[File:14_Zustand_Prognose_02.jpg|200px|thumb|right|Picture 2: Condition forecast of subsections of a single construction]]By combining the two methods it is possible to forecast how a structure's condition will change in the future, taking account of recognized damages and the effects ageing has on undamaged components. The sub-ratings of the different types of components which are obtained from structural inspection are used as the initial value for the current year. Figure 2 shows the evolution of the sub-ratings for a solid structure, steel structure and equipment starting from the initial values.
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[[de:Zustandsprognose]]

Condition forecast

2022-03-25T08:41:36Z

BAWiki Glossar:

[[File:14_Zustand_Prognose_01.jpg|200px|thumb|right|Picture 1: Typical gradient of a Herz curve]]In principle, each ageing structure is characterized by an ageing curve that describes the change in condition over time. The Herz function, due to its flexibility, is particularly suitable for representing the ageing of infrastructure elements and their components. Figure 1 shows the curve of a Herz function with a resistance period at the beginning where no ageing effect is observed. The function also allows describing very old structures.

The ageing process undergone by steel structures differs from that observed in solid structures or equipment. It is therefore necessary to obtain different ageing functions. To define the parameters of the functions, the Project Group Asset Management System conducted a Delphi interview. Based on this Delphi interview it was possible to systematically collect the expert knowledge available at the WSV and the BAW. As a result, ageing functions were obtained for different types of components in hydraulic structures. These functions can now be used to assess the current and future sub-ratings of the different components depending on their respective age, if no knowledge on damages is available.

[[File:14_Zustand_Prognose_02.jpg|200px|thumb|right|Picture 2: Condition forecast of subsections of a single construction]]A failure rate can be derived from the ageing function which can be used to define a Markov matrix. The Markov matrix describes the probability whether, for a specific time increment, a damage is assigned to another damage category (damage is getting worse) or whether it remains within the same category. The method is highly suitable for forecasting the progress of recognized damages. The BAW has defined 14 deterioration processes for describing the substantial damages occurring in waterway structures.

By combining the two methods it is possible to forecast how a structure's condition will change in the future, taking account of recognized damages and the effects ageing has on undamaged components. The sub-ratings of the different types of components which are obtained from structural inspection are used as the initial value for the current year. Figure 2 shows the evolution of the sub-ratings for a solid structure, steel structure and equipment starting from the initial values.
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[[de:Zustandsprognose]]

Evaluating the condition of solid structures

2022-03-25T08:39:05Z

BAWiki Glossar:

[[File:13_Zustand_Bauwerke_01.jpg|200px|thumb|right|Picture 1: Lock chamber (around 80 years old) and striking features]]Information about the composition of solid structures as a whole or of individual structural elements as well as about the properties of the construction materials used are essential prerequisites not only for standard safety considerations, but also in terms of estimating remaining service life and determining repair requirements.

[[File:13_Zustand_Bauwerke_02.jpg|200px|thumb|right|Picture 2: Schematic diagram of cores extracted from lock chambers]]
[[File:13_Zustand_Bauwerke_03.jpg|200px|thumb|right|Picture 3: Horizontal core from lock chamber wall (higher quality fringe area - loose core area)]]Older waterway constructions in particular were built under conditions and constraints with which we are no longer familiar. Not enough construction materials of identical quality were always available throughout some building projects and construction procedures also exercised much greater influence on the quality of building work (picture 1). However, because such influences are not usually documented in the engineering documentation, if such documentation exists at all, the condition of a structure can only be reliably assessed by performing a comprehensive building evaluation using core extractions and subsequently examining the material characteristics in the laboratory. In the case of structural elements such as lock-chamber walls, vertical holes are drilled through the entire structure to determine its fundamental composition and to detect any areas which may have different material properties (picture 2). This information is particularly important when considering a structure's static features. Short horizontal or vertical holes, on the other hand, are made to investigate the composition of the structure near its edges and, in particular, to obtain material samples from close to the surface of structural components; the material's durability characteristics can then be used to assess the structure's service life and need for repair (picture 3).

[[File:13_Zustand_Bauwerke_04.jpg|200px|thumb|right|Picture 4: Examination of drill hole with an endoscope]]In some structural elements made with less than top quality concrete the stress caused by the drilling procedure itself can be enough to lead to changes in, or the destruction of, the drill core. In these cases the drill holes may also need to be examined using an endoscope (picture 4). When taking core samples the BAW Code of Practice 'Core Extractions for Examinations of Constructions' should be observed. If the intention is to inject the structural element in order to reduce water penetration, it may be appropriate to carry out hydraulic pressure tests in the drill holes in preparation for the planning and performance of such measures.

As well as determining the concrete characteristics, such as frost resistance or residual alcali-silica reactivity, the concrete covering and the carbonation depth of reinforced structual elements (when assessing the corrosion protection of the reinforcement) and the chloride distribution in structural elements which are suspected of being contaminated with chloride as result of de-icing salt or sea water must also be determined and compared.

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[[de:Beurteilung des baulichen Zustandes von Massivbauwerken (Baustoffe)]]

Assessing the load-bearing capacity of closures on existing hydraulic steel structures (steel structures and corrosion protection)

2022-03-24T12:35:40Z

BAWiki Glossar:

[[File:12_Tragfestigkeitsbewertung_01.jpg|200px|thumb|right|Picture 1: Sample for a Charpy impact test]]
[[File:12_Tragfestigkeitsbewertung_02.jpg|200px|thumb|right|Picture 2: Test set-up for determining tensile strength]]The existing standards DIN EN 1993 (2010-12) and DIN 19704-1 (2014-11) set out regulations for verifying the load-bearing capacity of (new) closures on hydraulic steel structures. When these regulations are used to evaluate existing hydraulic steel structure closures, the permitted scopes of application are often exceeded. For instance, the requirements in terms of materials, tolerances and structural condition are incompatible with the properties of the closures within the remit of the German Federal Waterways and Shipping Administration (WSV), some of which are over 100 years old. This can lead to the load-bearing capacity being calculated inaccurately or incorrectly. The BAW therefore employs specific methods to take account of the unique characteristics of existing structures.

[[File:12_Tragfestigkeitsbewertung_03.jpg|200px|thumb|right|Picture 3: Microscopic analysis of surface finishes]]Several methods are used to determine the current condition of a structure in situ. The structural check of the load-bearing structure is carried out in several investigation steps of increasing thoroughness. Thus the assessment of load-bearing capacity makes a distinction between material behaviour at low temperatures (brittle fracture), load-bearing capacity at room temperature (forms of ductile failure) and load-bearing capacity under fatigue stress (material fatigue).

[[File:12_Tragfestigkeitsbewertung_04.jpg|200px|thumb|right|Picture 4: Inspecting a gate]]If the simplified method cannot be used to prove sufficient brittle-fracture resistance for the impact energy absorbed by the material sample taken, an assessment using fracture-mechanical methods must be carried out. The use of plastic cross-section reserves represents a verification method for existing hydraulic steel structures that, although new to the field, is necessary as far as the BAW is concerned. Compliance with the requisite material properties is established in the BAW’s laboratories. The partial safety coefficients for the stress factors are selected depending on the strength distribution (production time). The complex structures are modelled and studied using 3D finite element programs in order to produce realistic calculations of stresses and deformations.

[[File:12_Tragfestigkeitsbewertung_05.jpg|200px|thumb|right|Picture 5: Inspecting a gate]]
[[File:12_Tragfestigkeitsbewertung_06.jpg|200px|thumb|right|Picture 6: FE model of a section of gate]]Fatigue strength is generally evaluated by applying the idea of nominal stress in order to determine the residual useful life of the load-bearing structure. If required, the impact of corrosion is taken into account by modifying the Wöhler lines based on fatigue strength tests. The use of fracture-mechanical methods is also envisaged where components are already damaged by cracks.

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[[de:Tragfähigkeitsbewertung bestehender Stahlwasserbauverschlüsse (Stahlbau und Korrosionsschutz)]]

Shear strength of concrete and masonry

2022-03-24T12:32:23Z

BAWiki Glossar:

[[File:11_Scherfestigkeit_01.jpg|200px|thumb|right|Picture 1: Sample drilled out of a horizontal joint]]The coefficient of friction in construction and concreting joints in hydraulic structures made from unreinforced concrete or masonry can be determined by shear-testing samples of the structure taken from the joints.

[[File:11_Scherfestigkeit_02.jpg|200px|thumb|right|Picture 2: Shear test apparatus]]A large number of existing hydraulic structures are made from unreinforced concrete and masonry, both traditional construction methods for discharging normal forces. In the case of hydraulic structures, however, these structures often have to safely discharge high horizontal loads (shear loads) from earth and water pressure, e.g. at locks, weirs, seawalls and dams. In order to quantify resistance capability in construction and concreting joints in concrete structures of this kind, in joints in masonry constructions and in corresponding design sections in the bulk material, the size of the coefficient of friction – potentially in combination with corresponding cohesion components – is therefore crucial.

[[File:11_Scherfestigkeit_03.jpg|200px|thumb|right|Picture 3: Stress diagram from the shear test]]The actual coefficients of friction are not usually available, while the coefficients that are available based on the verification methods currently applicable to concrete structures are often highly unsuitable for the hydraulic structures mentioned. It therefore has to be possible to run tests to determine the shear strength of samples drilled out of the structure’s joints under the corresponding load conditions that actually apply.

The tests run in the BAW’s construction materials laboratory are based on rock tests and use a direct shear apparatus. First of all, the sample from the structure is fitted into a two-part sample holder in such a way that it can be sheared off horizontally (in the joint). A constant normal stress that is in line with the structural conditions is then applied to the sample in a vertical direction relative to the shear surface and the sample is then sheared off by being moved horizontally at a constant speed. The coefficient of friction can be calculated from the shear stress recorded along the shearing path during the shearing-off process.
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[[de:Scherfestigkeit von Beton und Mauerwerk]]

Non-linear probabilistic calculations

2022-03-24T12:30:26Z

BAWiki Glossar:

[[File:10_Probabilistische_Berech_01.jpg|200px|thumb|right|Picture 1: Crack formation in a niche section made from unreinforced concrete with 3D distribution of compressive strength in the vicinity of the loading]]The BAW’s TbW* Code of Practice enables more detailed investigation methods to be applied in a multi-stage process if the load-bearing capacity of existing solid hydraulic structures cannot be formally verified in a single step using the current regulations. The use of non-linear probabilistic calculations is illustrated below using the example of material properties: The broad spread of compositions and mixtures of the building materials used in solid construction prompts an approach whereby a 5 per cent quantile value is used for material properties.

The first stages in accordance with TbW apply this value according to the relevant material or construction period or set out tests that also result in 5 per cent quantile values. In the third stage in accordance with TbW, FEM simulations are used to map the non-linear material behaviour as realistically as possible, while employing probabilistic methods enables the anticipated range of the building material used to be taken into account.

[[File:10_Probabilistische_Berech_02.jpg|200px|thumb|right|Picture 2: Crack formation and breakout in a niche section made from unreinforced concrete with 3D distribution of compressive strength in the vicinity of the loading]]To this end, the material properties follow a characteristic curve that is imposed on the FEM model in a spatial distribution. Depending on its characteristics, the 3D variation can furnish decisive insights into the load-bearing capacity of the component in question and thus constitute a design parameter itself. The robustness of different combinations of spatial distributions and typical spread of variations in material properties is investigated in scenarios. The probability of failure and the level of reliability of the load cases under consideration are determined by the component’s behaviour patterns. Fig. 1 and Fig. 2 show examples of the different crack formations and damage that can be sustained in a niche section with the same pattern of load application and characteristic curve but with a different spatial distribution.

*TbW: German Federal Waterways Engineering and Research Institute (Ed.) (2016): BAW Code of Practice “Evaluation of the load bearing capacity of existing solid hydraulic structures” (TbW). Karlsruhe: German Federal Waterways Engineering and Research Institute (BAW Codes of Practice, Recommendations and Guidelines).

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[[de:Nichtlineare, probabilistische Berechnungen]]

Nonlinear structural engineering analysis (NiTrA)

2022-03-24T12:28:47Z

BAWiki Glossar:

[[File:08_Nitra_01.jpg|200px|thumb|right|Stresses and deformations with increasing load factor λ]]After approximately 40 years of operation a fatigue fracture was detected in the flexural tension reinforcement for the eastern chamber wall of the Bamberg lock (Main-Danube canal). Damages from material fatigue were also detected on other structures around the federal waterway. The BAW was asked to investigate the causes and report on its findings. Owing to the specific nature of material fatigue-related damages, the serious risks associated with them and their significance for other locks and hydraulic structures subject to cyclically recurring stresses, a comprehensive assessment needed to be undertaken of the structural safety of the locks along the Main-Danube canal and other federal waterways. The structural assessments are undertaken in the framework of a three-stage inspection programme, the last stage of which is a nonlinear system structural engineering analysis using the "NiTrA" system established for precisely this purpose.

Owing to the recurring revision of regulations since building work was completed, the formal application of current calculation standards using customary static models have proved insufficiently reliable. The reasons for this are the currently more demanding approaches to stress and impact combinations. The calculated load-bearing reserves arising from former static modelling, including cautious structural component resistances, are unable to compensate for these deficits. It is therefore important that the affected locks are statically modelled as realistically as possible. Realistically refers to a complex picture of the structure and ground, and the interactions between them. At the same time it is essential in a two-dimensional cross sectional consideration of the relevant lock chamber to take reasonable account of the geometry - bearing in mind its slab character (D areas) - as well as the material nonlinearities or the plastic behaviour of the reinforced concrete and the building ground.

Information about evidence of static load capacity based on nonlinear material behaviour and the requisite reliability format with the various reliability elements on the impact and resistance side are only dealt with briefly in the applicable standards. Basic requirements for reinforced concrete structures are stated in Section 8.5.1 of DIN 1045-1 (2008) or in the relevant section in the German Committee for Reinforced Concrete's (DAfStb) Book 525. These stipulations will be integrated in the national implementation document for the European Reinforced Concrete Code EC2.

DIN 1054 (2005) does not make any specific stipulations in the geotechnical field. It is only recently that recommendations have been elaborated in the context of work on Eurocode EC 7; however, these recommendations relate exclusively to geotechnical issues. There are still no satisfactory stipulations for a balanced reliability format for numerical studies of complex load-bearing systems consisting of building ground and reinforced concrete. In the framework of the stability studies on the reinforced concrete locks referred to above, a proof concept first needed to be drawn up and formulated which would guarantee a standardised, reproducible verification procedure at all locks and other solid hydraulic structures. This "concept for the static verification of the system load bearing capacity of locks on the basis of nonlinear material behaviour - NiTra" has already been successfully used several times and allows calculatory safety margins to be elicited and documented which the verification methods typically used in practical engineering are unable to provide.

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[[de:Nichtlineare Tragwerksanalyse (NiTrA) (Massivbau)]]

Corrosion protection tests (steel structures and corrosion protection)

2022-03-24T12:27:47Z

BAWiki Glossar:

[[File:07_Korrosionsschutzpruefung_01.jpg|200px|thumb|right|Picture 1: Long-term exposure of coating samples at the Kiel site]]The wide range of stresses to which coatings of hydraulic steel structures are exposed calls for an appropriate testing programme to provide qualitative evidence of their suitability. Besides standardised corrosion protection tests (e.g. resistance to neutral salt spray), additional test procedures to address the WSV’s specific requirements (e.g. condensate water changing test and abrasion test as well as a cathodic protection compatibility test) are also employed.

[[File:07_Korrosionsschutzpruefung_02.jpg|200px|thumb|right|Picture 2: Analysing long-term exposure samples at Kiel]]Ultimately, the coating systems tested in the lab have to reproduce the evidence of their suitability in a natural environment. The BAW has four exposure locations that it can use for this purpose, two river sites in Trier and Windheim and two coastal sites in Kiel and Büsum. The protective properties of all coating systems are studied at these sites over a five-year period in various stress zones in order to guarantee that any coating systems that have been optimised based on laboratory tests have their strengths and weaknesses investigated thoroughly.

As well as qualitative tests of corrosion protection coatings run on behalf of the WSV, aspects such as specific corrosion scenarios (microbial corrosion (MIC) or bimetallic corrosion), an ecotoxicological analysis of the coating materials used and/or cost-effective alternative repair methods ("smart repair") are also studied.
<gallery>
File:07_Korrosionsschutzpruefung_03.jpg|Picture 3: Rust creep test at the scribe of a sample from long-term exposure
File:07_Korrosionsschutzpruefung_04.jpg|Picture 4: BAW test to determine the suitability of coatings for cathodic protection (CP)
File:07_Korrosionsschutzpruefung_05.jpg|Picture 5: Coating samples undergoing a salt spray test
File:07_Korrosionsschutzpruefung_06.jpg|Picture 6: Coating thickness measurement and pull-offs on tested coatings
File:07_Korrosionsschutzpruefung_07.jpg|Picture 7: Measuring the potential distribution of a CP-protected canal bridge
File:07_Korrosionsschutzpruefung_08.jpg|Picture 8: Colour measurement on a lock gate

</gallery>

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[[de:Korrosionsschutzprüfungen (Stahlbau und Korrosionsschutz)]]

Development of Hydration Heat in Concrete

2022-03-24T12:08:39Z

BAWiki Glossar:

The setting of concrete leads to the release of hydration heat which can result in a significant temperature increase, particularly in structural elements. This reaction causes massive stresses which, in turn, may lead to the formation of cracks in the concrete. The resulting temperature difference developed in the process is of particular importance.

[[File:06_Hydrationswaermeentwicklung_01.jpg|200px|thumb|right|Picture 1: Manufacturing of the large-format concrete block for temperature measurements]]The BAW's Supplementary Technical Contract Conditions for Hydraulic Engineering, Division 215 - Hydraulic Structures Made of Concrete or Reinforced Concrete ("Zusätzliche Technische Vertragsbedingungen - Wasserbau, Leistungsbereich 215 (ZTV-W LB 215)") account for this phenomenon by limiting the quasi adiabatic temperature increase in concrete and thus the resulting temperature in the structural component. The quasi adiabatic temperature increase is used in the assessment of thermal restraint due to hydration heat.

[[File:06_Hydrationswaermeentwicklung_02.jpg|200px|thumb|right|Picture 2: The BAW's adiabatic concrete calorimeter]]Various test methods are suitable for recording the temperature increase. They can generally be categorized into on-site tests on the one hand, and laboratory tests on the other hand. As a rule, contractors prove compliance with the requirements according to the ZTV-W LB 215 for concretes to be used in solid structural components by on-site temperature measurements performed on large-format insulated concrete blocks with an edge length of 2 m (picture 1). The provisions of the ZTV-W LB 215 detail the boundary conditions for the test. It can be assumed that this test set-up fullfils quasi adiabatic boundary conditions. It also takes account of the influences the manufacturing process has on the concrete, i.e. influences relating to production, transport and casting.

[[File:06_Hydrationswaermeentwicklung_03.jpg|200px|thumb|right|Picture 3: Profile of the temperature development in a large-format concrete block and in the adiabatic concrete calorimeter]]In the BAW's construction materials laboratory the adiabatic temperature increase of concrete is measured - as part of the inspection tests performed by the client - with an adiabatic concrete calorimeter (picture 2). Such devices are not widely available on the market; the BAW currently has two devices that are the products of in-house development work.

The concrete's temperature is recorded and evaluated over a 7-day period, both in the on-site test performed on the concrete block and in the adiabatic calorimeter (picture 3).

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[[de:Hydratationswärmeentwicklung von Beton (Baustoffe)]]

Assessing the Freeze-Thaw Resistance of Concrete

2022-03-24T12:05:59Z

BAWiki Glossar:

[[File:05_Frostwiderstand_01.jpg|200px|thumb|right|Picture 1: Frost-determined weathering of a lock-chamber wall]]Hydraulic concrete structures are subject to particularly extreme freeze-thaw attack (see picture 1) due to freeze-thaw cycles depending on operation and tides and also because of the high degree of saturation resulting from direct exposure to water. To ensure sufficient durability considering the increased requirements [compared to DIN 1045] concerning service life, concrete source materials and concrete composition additional freeze-thaw laboratory tests are conducted.

The BAW has worked intensely, together with the University of Essen, on defining a freeze-thaw laboratory test and elaborating test criteria relevant for hydraulic engineering. In parallel with these efforts, the BAW is also conducting extensive studies, in collaboration with RWTH Aachen University, on the actual temperature and moisture levels in concrete structures in order to be able to transfer the results obtained from freeze-thaw laboratory tests to practical conditions.

[[File:05_Frostwiderstand_02.jpg|200px|thumb|right|Picture 2: Schematic diagram, frost resistance test according to BAW Code of Practice]]The BAW Code of Practice "Freeze-Thaw Testing of Concrete" which was issued in 2004 governs frost resistance tests and related test criteria. The frost resistence test method selected is the CDF/CIF method (CDF: '''C'''apillary suction of '''D'''eicing solutions and '''F'''reeze-thaw test; CIF: '''C'''apillary suction, '''I'''nternal damage and '''F'''reeze-thaw test); the acceptance criteria relate to the change of the dynamic modulus of elasticity as an indicator of internal damage and the sealing of material from the area exposed to freeze (picture 2). The acceptance criteria apply to test specimens cured according to the BAW Code of Practice. Further investigations will be required for the evaluation of core samples from structures.

The BAW's Supplementary Technical Contract Conditions applicable to new hydraulic structures (ZTV-W LB 215) and to the repair of existing hydraulic structures (ZTV-W LB 219) make reference to the BAW Code of Practice "Freeze-Thaw Testing of Concrete". Based on this Code of Practice, freeze-thaw and freeze-thaw de-icing salt resistance tests of concrete are, however, not only conducted in hydraulic engineering but also in many other engineering areas. The DIBt has also adopted the BAW Code of Practice for its own approval procedures.

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[[de:Beurteilung des Frostwiderstands von Beton (Baustoffe)]]

Durability tests for rebar corrosion

2022-03-24T12:03:51Z

BAWiki Glossar:

Practical verification methods enable the performance-based analysis and testing of rebar structures in terms of the carbonation- and chloride-induced corrosion of the reinforcements.

[[File:04_Dauerhaftigkeitsbemessung_01.jpg|200px|thumb|right|Picture 1: Chloride-induced corrosion on the supporting beam of a jetty]]The durability of structures in sea water is heavily dependent on the risk of chloride-induced corrosion affecting their reinforcements. Various cases of damage demonstrate that chloride-penetration resistance cannot always be reliably ensured even if the standard requirements in accordance with DIN 1045-2 are complied with. Structures in waterways are thus subject to additional requirements governing the composition of concrete exposed to chlorides. Furthermore, the additional technical terms and conditions of contract ZTV-W LB 215 and ZTV-W LB 219 require durability tests to be performed on components in exposure classes XS2 and XS3 that have expected useful lives of over 50 years. The introduction of the factsheet entitled [https://izw.baw.de/publikationen/merkblaetter/0/BAWMerkblatt_Dauerhaftigkeitsbemessung_MDCC_2019.pdf "Testing and evaluating the durability of rebar structures exposed to carbonation and the impact of chlorides (MDCC)" (2019)] sets out performance-based strategies for:

* testing the durability of new rebar components to be constructed,
* evaluating the durability of existing rebar components, and
* testing the durability of rebar structures to be repaired using concrete replacement

[[File:04_Dauerhaftigkeitsbemessung_02.jpg|200px|thumb|right|Picture 2: Measurement nomogram for chloride-induced reinforcement corrosion]]in respect of carbonation- and chloride-induced rebar corrosion. The practical tools provided enable everyone involved in a construction project (planners, construction material manufacturers, contractors, client) to address the issue of the durability of rebar structures in a transparent way in respect of reinforcement corrosion.

[[File:04_Dauerhaftigkeitsbemessung_03.jpg|200px|thumb|right|Picture 3: Quick laboratory test method for chloride migration]]The verification format is based on the results of fully probabilistic calculations using validated prediction models. The first measurement nomograms compare the key parameters (impact, material resistance, concrete cover, useful life) for various levels of reliability (Figure 2).

The chloride-penetration resistance can be determined by means of a diffusion test (for materials of an unknown composition, e.g. repair products) or an RCM test (for materials of a known composition, e.g. concrete) (Figure 3).

The BAW’s MDCC factsheet also details similar approaches for verifying durability in respect of carbonation.

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[[de:Dauerhaftigkeitsbemessung hinsichtlich Betonstahlkorrosion]]

File:03 Chemische Analytik 03.jpg

2022-03-24T12:00:45Z

BAWiki Glossar:

Analysis and Testing of Construction and Coating Materials

2022-03-24T12:00:33Z

BAWiki Glossar:

[[File:03_Chemische_Analytik_01.jpg|200px|thumb|right|Picture 1: Examinations in the chemistry laboratory]]In the BAW's chemistry and corrosion laboratory, the BAW staff analyse and evaluate the composition, suitability and/or quality of construction and coating materials as well as other materials by applying special physical and chemical testing methods.

== FTIR-Spectroscopy ==

Fourier transform infra-red spectroscopy (FTIR spectroscopy) is an analytical method for the definition and study of anorganic/organic molecule groups. By producing infra-red spectrums with typical absorption bands, the molecular character and the composition of materials (construction materials elastomeres, coatings) can be deduced. Examples of such investigations are:

* the identification of coating materials for quality assurance (finger print)
* the verification of composition or hardening reaction problems in coating materials and the examination of carbamate formation in amine hardeners of epoxy resin coatings
* determining mineral phases in concrete and masonry salts
* determining the corrosion products and deducing the source of the corrosion

FTIR spectroscopy thus permits fast and high-quality analysis of construction materials in general and of coating materials in particular.

== Thermal Analysis with an Assembly for Concurrent TGA and DTA ==

[[File:03_Chemische_Analytik_02.jpg|200px|thumb|right|Picture 2: Chemical laboratory at the BAW]]The assembly for concurrent thermogravimetric analysis (TGA) and differential thermal analysis (DTA) is used to obtain information on decomposition temperatures, physical processes (melting, phase transition) and on the presence of specific components of the concrete (e.g. quartz, portlandite, ettringite and calcite). Further applications include:

* determination of the residual solvent content in coating samples
* thermal gravimetric analysis of concrete specimens, elastomers and corrosion products
* detection of mixing or hardening problems in two-component coatings

The TGA analysis allows increases in the informative value and the verification of other test results.

== Headspace Gas Chromatography (HS-GC) ==

[[File:03_Chemische_Analytik_03.jpg|200px|thumb|right|Picture 3: Reflected-light microscope images of coating samples, minerals and surface finishes]]This chromatographic analysis method is used to screen for specific, volatile substances in a polymeric matrix. Thus it is possible, even after the polymer has hardened, to determine whether non-complying or incompatible solvents were used when applying coatings to steel and hydraulic steel structures. The question regarding the cause of failure of the corrosion protection can thus be clarified. The method can also be used for:

* the detection of toxic alkyloximes and aromates in alkyd resins
* multiple headspace extraction (MHE) to quantify residual solvent contents
* the development of profiles (finger print) for various diluting agents and solvent mixtures

== Atomic Absorption Spectrometry - AAS ==

[[File:03_Chemische_Analytik_04.jpg|200px|thumb|right|Picture 3: Micrograph of a coating sample]]This spectroscopic analysis method is used to quantitatively determine various elements contained in different materials. It is possible, for example, to establish the composition of steel, alloys and corrosion products. The analysis of binders in concrete specimens thus includes the characterisation of the binder (cement type), taking into account the carbon and sulphur content, and the quantitative determination of the composition of old concrete.

== Microscopy ==

Using the incident light microscope it is possible to analyse the morphology and structure of material specimens, at a magnification of up to 500X. The structure of applied layers, the succession of the individual layers and any faults (blisters, inclusions, pores, etc.) can thus be determined, especially in coating samples. Based on computer-aided image analysis it is also possible to determine other characteristics such as the material strengths of the individual layers or the size of underfilm corrosion surfaces. Metallographical structure investigations (structure, texture, particle size) are also carried out using a reflected light microscope. In special cases, such as the determination of mineral phase and structure, thin sections with a transmitted light microscope (polarising microscope) will be used.

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[[de:Analyse und Prüfung von Bau- und Beschichtungsstoffen (Stahlbau und Korrosionsschutz)]]

Alkali Reactivity of Aggregates and Concretes

2022-03-24T11:57:10Z

BAWiki Glossar:

[[File:02_Alkali_Kieselsaeure_R_01.jpg|200px|thumb|right|Picture 1: Expansion cracks in a lock chamber]]Alkali-reactive aggregates in concrete may cause expansion due to a damaging alkali-silica reaction (ASR), resulting in serious cracking. The BAW's construction materials laboratory conducts special laboratory tests to prevent such damages from ocurring in new construction or repair measures or to determine the residual reactivity of constructions already damaged.

[[File:02_Alkali_Kieselsaeure_R_02.jpg|200px|thumb|right|Picture 2: Specimens in the fog chamber (40°C)]]If the concrete contains materials that are prone to a damaging ASR, i.e. materials with a higher alkali content and alkali-reactive rocks, waterway structures are significantly more likely to exhibit this reaction due to the ever-present moisture (solid structural elements, exposure to water) than e.g. engineering structures in building construction. Even minor previous damages, e.g. resulting from cracks caused by restraints due to hydration heat, can trigger a damaging ASR in the long term, even if the aggregates in question show only low reactivity (picture 1).

[[File:02_Alkali_Kieselsaeure_R_03.jpg|200px|thumb|right|Picture 3: Expansion diagram of core samples]]Therefore, to prevent any such damages, additional suitability tests following the alkali guideline issued by the German Committe for Reinforced Concrete (DAfStb) are performed whenever a material is suspected of being alkali-reactive (e.g. when using specific aggregates that cannot be clearly assessed according to the relevant regulations). For these tests, specimens are manufactured, using the planned concrete formulations, and kept for 9 months in a fog chamber at a temperature of 40°C (picture 2). During that time, data is gathered, not only on obvious damages (formation of cracks, gel exudation) but also on expansions (picture 3) and changes in the structure (relativ elastic modulus).

If concrete structures already exhibit damages with the typical ASR-related features, core samples are obtained from the damaged structures and exposed to a fog chamber (40°C) to accelerate the reaction; thus it is possible to identify the cause and degree of the damage as well as the residual potential expansion of the concrete. In addition to the above-mentioned evaluation procedures, any potential losses in strength are immediately rated by determining the residual strength after exposure to the fog chamber. These examinations are necessary for assessing bearing capacity and serviceability as well as possible repair measures, if required.

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[[de:Alkalireaktivität von Gesteinskörnungen und Betonen (Baustoffe)]]

Alkali Reactivity of Aggregates and Concretes

2022-03-22T11:40:39Z

BAWiki Glossar:

[[File:02_Alkali_Kieselsaeure_R_01.jpg|200px|thumb|right|Picture 1: Treibrisse an einer Schleusenkammer]]Alkali-reactive aggregates in concrete may cause expansion due to a damaging alkali-silica reaction (ASR), resulting in serious cracking. The BAW's construction materials laboratory conducts special laboratory tests to prevent such damages from ocurring in new construction or repair measures or to determine the residual reactivity of constructions already damaged.

[[File:02_Alkali_Kieselsaeure_R_02.jpg|200px|thumb|right|Picture 2:]]If the concrete contains materials that are prone to a damaging ASR, i.e. materials with a higher alkali content and alkali-reactive rocks, waterway structures are significantly more likely to exhibit this reaction due to the ever-present moisture (solid structural elements, exposure to water) than e.g. engineering structures in building construction. Even minor previous damages, e.g. resulting from cracks caused by restraints due to hydration heat, can trigger a damaging ASR in the long term, even if the aggregates in question show only low reactivity (picture 1).

[[File:02_Alkali_Kieselsaeure_R_03.jpg|200px|thumb|right|Picture 2:]]Therefore, to prevent any such damages, additional suitability tests following the alkali guideline issued by the German Committe for Reinforced Concrete (DAfStb) are performed whenever a material is suspected of being alkali-reactive (e.g. when using specific aggregates that cannot be clearly assessed according to the relevant regulations). For these tests, specimens are manufactured, using the planned concrete formulations, and kept for 9 months in a fog chamber at a temperature of 40°C (picture 2). During that time, data is gathered, not only on obvious damages (formation of cracks, gel exudation) but also on expansions (picture 3) and changes in the structure (relativ elastic modulus).

If concrete structures already exhibit damages with the typical ASR-related features, core samples are obtained from the damaged structures and exposed to a fog chamber (40°C) to accelerate the reaction; thus it is possible to identify the cause and degree of the damage as well as the residual potential expansion of the concrete. In addition to the above-mentioned evaluation procedures, any potential losses in strength are immediately rated by determining the residual strength after exposure to the fog chamber. These examinations are necessary for assessing bearing capacity and serviceability as well as possible repair measures, if required.

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[[de:Alkalireaktivität von Gesteinskörnungen und Betonen (Baustoffe)]]