Influence of Strength Anisotropy on Piezocone Resistance in Clay

Abstract

Since different undrained shear strengths may be obtained from different laboratory or field tests, different cone factors are needed to calculate the undrained shear strengths from the results of a piezocone test in clay. Based on the anisotropic undrained shear strength criterion, a set of cone factors for calculating undrained shear strength is proposed in this paper. These cone factors are interrelated with each other in terms of the strength anisotropy ratio of the clay. The suitability of the proposed cone factors has been verified using the test results generated from different tests and from clays with different origins. By comparing with the cone factor for isotropic clay, it was found that the effect of strength anisotropy on the cone factor is not always significant. In fact, the effect of strength anisotropy becomes significant only in lightly overconsolidated to normally consolidated clay with moderate to high strength anisotropy. Furthermore, the maximum difference in cone factor is not expected to exceed 20% with or without taking into account the strength anisotropy of clay.