Insitu Penetration Tests
InSitu Ground penetration tests.
Any investigation technique that involves excavation, drilling and obtaining samples will unavoidably disturb the ground and alter the surrounding insitu stresses. Penetration tests can reduce, but not entirely eliminate, this problem by driving or pushing a probe into the ground. Although this approach will still cause some disturbance to the ground intersected, the resistance to penetration can be measured to give a reasonable indication of the consistency, density and stiffness of the strata under investigation. Often insitu testing is undertaken concurrently with borehole drilling to provide additional information.
Penetration tests include widely adopted techniques such as the standard penetration test (SPT) where a steel tube sampler is driven below the base of a drilled borehole, the cone penetration test (CPT) where an instrumented cone shaped probe is hydraulically pushed into the ground and low technology hand held tests such as a dynamic cone penetration (DCP) and Perth Sand Penetration (PSP) tests. These tests range in sophistication, depth capability and cost and so must be carefully selected to suit the anticipated ground conditions and project requirements such as excavation depths and proposed foundation types.
Penetration tests do not directly measure the soil properties of interest and so correlations to previous test data, and site calibration, are relied upon to assess the nature, density, strength and stiffness of the ground strata. The main advantage of penetration testing is that these tests have been very widely used for a long time and so correlations are well developed, many tests are fast and relatively simple to conduct and generally costs are relatively low compared to other investigation techniques.
The CMW team are familiar with and frequently conduct a wide range of penetration tests such that the selection, scoping, execution and presentation of relevant tests is routinely incorporated into our geotechnical investigations. Our extensive experience in the review and interpretation of penetration test data facilities efficient determination of optimum design parameters for incorporation into the ground model and input into the analysis and design process.