Pore pressures induced by piezocone penetration

Abstract

The excess pore-water pressures (u) induced by piezocone penetration and their dissipation around the cone have been investigated by laboratory model tests and theoretical–numerical analyses. Based on the test results, a method for predicting cone penetration–induced distribution of u has been proposed. By numerical analysis using the predicted initial distribution of u it has been demonstrated that dissipation of the pore-water pressure measured at the shoulder of the cone (u2-type cone) is a two-dimensional (horizontal radial and vertical) process. A back-fitted coefficient of consolidation in the horizontal direction (ch) can be obtained by comparing the simulated and laboratory-measured two-dimensional dissipation curves. It has also been shown that a published method for estimating ch from measured nonstandard dissipation curves (in which u2 increases initially and then decreases) results in values of ch that agree well with values of ch deduced from the two-dimensional analysis.

A modified method for estimating permeability of clayey soils based on piezocone sounding results

“…These measurements can be used to estimate the undrained shear strength of a deposit (s u ) (Campanella and Robertson 1988; Teh and Houlsby 1991;Lu et al 2004), overconsolidation ratio (OCR) (Wroth 1984;Mayne and Kemper 1988;Robertson 1990;Chanmee et al 2017) and permeability of soil in the horizontal direction (k h ) (Robertson et al 1992;Lunne et al 1997;Sully et al 1999;Elsworth and Lee 2005;Robertson 2010;Chai et al 2011). The cone can be held at a predetermined depth to measure the pore pressure dissipation process, and these dissipation results can be used to estimate the coefficient of consolidation of the soil at that depth (Teh and Houlsby 1991;Robertson et al 1992;Burns and Mayne 1998;Chai et al 2012a;Chai et al 2015).…”