Effects of Tunneling-Induced Ground Movements on Stability of Piled Raft Foundation: Three-Dimensional Finite-Element Approach

Abstract

Across the globe, rapid urbanization demands the construction of tunnels within the vicinity of high-rise buildings supported on piled raft foundations. As a consequence, ground movements caused by such tunneling works could interfere with the serviceability of the foundations. Hence, the prediction of tunnel-induced ground deformation is of utmost importance. In the current study, a three-dimensional numerical analysis was carried out to study the response of an existing piled raft foundation with a 2 × 2 pile arrangement subjected to ground movements induced by a 6 m-diameter tunnel. The results obtained from the numerical simulations were further compared with a field study. The field measured lateral pile deflections were found to be in fair agreement with those computed using the present method. The numerical analysis was then extended to understand the influence of various factors, such as tunnel diameter, tunnel longitudinal axis, pile diameter, pile position from tunnel, and soil stiffness on the response of pile raft in the vicinity of an adjacent tunnel. The results obtained from the parametric study was finally summarized in simple semi-empirical equations to estimate the maximum lateral deflection and bending moment for both short and long piles.