Evaluation of train-load-induced settlement in metro tunnels

Abstract

Based on a simplified mechanical model, the stress distribution pattern in subsoils around tunnels due to train movement is investigated. In this model, the effects of rails, connection bolts, ballast, lining and foundation are taken into account. The initial stress state and the dynamic stress state of the subsoils induced by train loading are obtained from a two-dimensional finite-element calculation. After combining the above results with the empirical equation proposed by Chai and Miura in 2002, the cumulative plastic strain of subsoils and the long-term settlement of tunnels are obtained. The results show that the cumulative train-load-induced tunnel settlement increased, but at a decreasing rate. The cumulative settlement was 15·5 mm after 8 years, 60% of which occurred within the initial 6 months.