FIELD PRESSUREMETER

The pressuremeter test is an in-situ testing method used to achieve a quick measure of the in-situ stress-strain relationship of the soil. In principle, the pressuremeter test is performed by applying pressure to the sidewalls of a borehole and observing the corresponding deformation.

The pressuremeter consists of two parts, the read-out unit which rests on the ground surface, and the probe that is inserted into the borehole (ground). As the pressure increases, the borehole wal s deform. The pressure is held constant for a given period and the increase in volume required for maintaining the constant pressure is recorded.

A load-deformation diagram and soil characteristics can be deduced by measurement of the applied pressure and change in the volume of the expanding membrane.

From the test readings (volume variation based on control ed pressure), a stress-strain curve can be obtained, in the case of plane deformation, which yields :

• the Ménard Pressuremeter modulus

• the creep pressure

• the Menard limit pressure