Coupled Eulerian-Lagrangian simulation of progressive failure in shield tunnels induced by developing contact loss

Abstract

Contact loss may develop between a shield tunnel and the surrounding ground due to various factors. This study evaluated the deformation and failure of shield tunnels caused by contact loss using the Coupled Eulerian-Lagrangian (CEL) method. Three-dimensional finite element models considering the behavior of segment joints were established. The CEL method for simulating contact loss and the segmental tunnel model were validated through two existing experiments. The shield tunnel structure responses, including convergent displacement of linings, dislocation between tunnel rings and joint failure process, were analyzed under typical cases of contact loss developing circumferentially and longitudinally. In addition, the impact of contact loss location was investigated. The results show that significant joint dislocation may occur at the boundary of the contact loss region. When contact loss develops to a certain level, the tunnel deformation may increase sharply, and many segment joints fail suddenly. Additionally, more joints fail when the contact loss is located at the tunnel crown than when contact loss is located at the tunnel invert and springline due to the assembled method of shield tunnel in this study in which the key segments were all positioned at the tunnel crown.