Pore Pressure Responses of Overconsolidated Soils in a Partially Drained Piezocone Penetration Test

Abstract

This study investigated the pore pressure responses of overconsolidated (OC) soils during a piezocone penetration test (PCPT). The influences of overconsolidation ratio (OCR) and hydraulic conductivity were accounted in investigating the generated pore pressures during the PCPT. The modified Cam-clay model and Darcy’s law were incorporated in the quasi-static Biot theory to study the fluid-mechanical interaction during PCPT. The study found that a substantial negative pore pressure could be developed at the u2 position (cone shoulder) for heavily OC soils with low hydraulic conductivity. Moreover, an increase in u2 pore pressure was observed for a hydraulic conductivity range from 10−10 to 10−8 m/s. This was attributed to the instantaneous dissipation of shear generated negative pore pressure due to the diffusion of positive pore pressure from the u1 position (cone face), where the diffusion process is faster in high hydraulic conductivity condition. The findings of this study could explain a complicated multiphysics problem, and therefore may enhance the general understanding of PCPT results and the accuracy of specialized techniques such as on-the-fly estimation of the hydraulic conductivity of soils.