Influence of the soil profile randomness on the seismic response of multilayered soils with a rigid inclusion

Abstract

The paper deals with the seismic response of a multilayered soil. It focuses on the influence of the uncertainty that may affect the soil height (SH). The soil under study is considered as a superposition of layers that extend horizontally to infinity. A tunnel, located inside this soil, is supposed to behave as a rigid inclusion; it represents a part of the Algiers subway. Its dynamical response is investigated under Boumerdes earthquake effect, 21 May 2003 (Mw = 6.5). The soil accelerations are collected at Keddara station (12 km from the epicentre) as it corresponds to bedrock. As the study is devoted herein to SH wave propagation, the accelerations under study correspond to the EW horizontal direction. The SH below the tunnel is assumed to be a random variable. For this purpose, a log-normal distribution is adopted. The probabilistic seismic response of the soil is thus investigated. The mean and standard deviation of the tunnel displacement as well as of both the extreme ground acceleration and the transfer function are analysed. The present analysis is based on the boundary element method, which is adequate for the case of systems with infinite boundaries, while Green's functions are calculated using the thin layer method. Copyright © 2007 John Wiley & Sons, Ltd.