Finite element analysis of long-term surface settlement above a shallow tunnel in soft ground

Abstract

The construction of a tunnel in soft ground generally induces short-term and long-term ground settlements above the tunnel. In this study, finite element analysis of surface settlement above a shallow tunnel in clay till was performed. Field observations were performed to monitor the ground settlements above the tunnel and pore pressure changes around the tunnel. Four cases were simulated to investigate the influences of soil creep and flow boundary on surface settlement above the tunnel. The predicted surface settlement and pore pressure change were compared with those from field observations. From this study, it was found that creep behavior of the clay till played an important role in quantifying the long-term settlements above the tunnel, and the primary lining used in the tunnel construction could be approximately simulated by permeable flow boundary at the tunnel periphery. In addition, the influence of concrete lining installation on the long-term surface settlement was discussed.