English：

Taking a double-track shield tunnel project under a railway in Tianjin as the research object,numerical simulation was conducted on the shield tunneling process, to study the influence law in soft soilarea on deformation of different pile foundation positions and pile lengths. The research results show that,when the pile foundation locates on one side of the double-track tunnel, the horizontal displacement of thepile foundation basically reaches the maximum at the tunnel crown. As the pile foundation is farther awayfrom the tunnel, the horizontal displacement of the pile foundation gradually decreases. When the tunnelpasses under the railway and side-passes the pile foundation, the side-passing distance should beincreased as much as possible, to reduce the impact of tunnel excavation on pile foundation. When thepile foundation locates between the double-track tunnels, the deformation of the pile foundation is largerwhen it is closer to the tunnel. As the left and right line tunnels are constructed successively, the pilefoundation is disturbed multiple times,which affects the upper structure. When the pile foundation isshort and the bottom end is higher than the top of the tunnel, the influence of shield tunnel constructionon the deformation of the pile body is small. When the pile foundation is long and the bottom end is lowerthan the bottom of the tunnel, the pile body undergoes deformation mainly in bending, and the maximumhorizontal displacement occurs near the horizontal axis of the tunnel.