The Use of P-wave Velocity Tomography - A Particular Application on Exploring the Mechanism of Friction Fatigue

This paper aims to use a tomographic image system to obtain the spatial distribution of P-wave velocity in soil and then to derive the associated shear modulus (Gmax). The derivation is based on the relationship between Vp and Vs and the fact that the measured Poisson's ratio μ is fairly independent of the stress state. This tomographic image technique is also utilized in a jacked model pile test to explore the underlying mechanism of friction fatigue. The experimental results demonstrate that the shear modulus (Gmax) in the soil surrounding the pile decreases after the pile is subjected cyclic loading. Such a decrease may lead to the decrease of the ultimate radial stress on the pile shaft and eventually to reduce the ultimate shaft resistance, i.e., the result of friction fatigue during pile installation. © 2015 Taylor & Francis Group.