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

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 ${\mathrm{u}}_2$ position (cone shoulder) for heavily OC soils with low hydraulic conductivity. Moreover, an increase in ${\mathrm{u}}_2$ pore pressure was observed for a hydraulic conductivity range from ${10}^{-10}$ to ${10}^{-8}\mathrm{m}/\mathrm{s}$. This was attributed to the instantaneous dissipation of shear generated negative pore pressure due to the diffusion of positive pore pressure from the ${\mathrm{u}}_1$ 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.