Description

1.    Cone Penetration Test with pore water pressure measurement (CPTU)
A cone penetration test with pore water pressure measurement, or CPTU, is a static penetration test with water pressure measurement.

The main purpose of CPT (CPTU) testing is to identify subsurface conditions: classify soil, detect layers and measure strength, determine deformation characteristics and the permeability of foundation soils. This is done mainly on the basis of empirical correlations, and also partly on the basis of theoretical outlines.

The CPT experiment is performed by pressing the pointed probe into the soil vertically using pressing rods. The pointed probe must be pressed into the soil at a constant speed. It is necessary to measure the resistance of the pointed probe with pore water pressure (qc) and, if appropriate, the local friction sleeve on the probe (between the friction sleeve and the surrounding soil).
In addition to friction resistance and friction on the sleeve, it is possible to measure the water pressure (CPTU) and collect data on seismic waves (SCPT).
2.    Field Vane Shear Test (FVST)
The vane shear test is an in-situ geotechnical testing methods used to estimate the undrained shear strength of fully saturated clays without disturbance. The test is relatively simple, quick, and provides a cost-effective way of estimating the soil shear strength; therefore, it is widely used in geotechnical investigations. Under special condition, the vane shear test can be also carried out in the laboratory on undisturbed soil specimens; however, the use of the vane shear test in in-situ testing is much more common.
3.    The pressuremeter test
The pressuremeter test is an in-situ testing method used to determine the stress-strain response of the tested soil. The pressuremeter test, also known as the “Ménard Pressuremeter” (MPM) test, is performed by applying pressure to the sidewalls of a borehole and recording the corresponding deformation. The test procedure involves drilling a borehole and placing a pressuremeter probe to the required depth. The probe consists of three inflatable cells which are filled with water and gas. A control unit is set up near the borehole to pump water and gas while recording the measurements. As the pressure increases, the borehole walls deform. The pressure is held constant for a given period and the increase of the volume required for maintaining the constant pressure is recorded. The interpreted results are used to estimate the soil’s stiffness, strength, and the “at-rest horizontal earth pressure”.
4.    Dynamic Cone Penetration (DCP)
Dynamic Cone Penetration (DCP) testing is used to measure the strength of in-situ soil and the thickness and location of subsurface soil layers.