Geotechnical laboratory testing
From BAWiki
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
back to: Geotechnical Engineering Methods