Effect of Disturbance on Pressuremeter Results in Clays

Abstract

The installation of the pressuremeter probe in the ground causes disturbance to the adjacent soil, resulting in the formation of an annular zone of remolded soil around the probe. In the conventional pressuremeter test, disturbance is caused by temporary unloading of the borehole until the probe is inserted and inflated. In this study the disturbance was modelled by (1) Assuming a remolded annulus of soil around the probe; and (2) considering initial unloading and reloading of the cavity wall. A parametric study was conducted by varying the thickness of the remolded zone and the amount of initial unloading. The results indicate that the error in the undrained strength due to initial unloading can be higher than that due to the remolded zone. The modulus is affected by both the unloading and the size of the disturbed annulus. Further, an examination of field data indicates that strain‐softening soils are affected most by the disturbance caused by initial unloading of the cavity wall.