Abstract:

The loading of pile foundations may cause displacement and stress variation of the surrounding ground, which may further pose impact on the internal force and displacement of adjacent tunnels, especially under the action of pile group foundations. In this paper, comparison and contrast is made among 3 models, including the model with the pile group being above the tunnel roof, the model with the pile group extending below the failure surface of the tunnel sidewall and the model with the pile group extending below the tunnel floor, by means of finite element software, and the variation of the displacement of the tunnel and the variation of the internal force of the lining under the loading of the pile foundation are analyzed, with a largespan rock station of Chongqing Metro as an example. The analysis shows that: Under the condition of huge pile foundation loading and big tunnel span, the lining structure of the tunnel will be damaged when the pile foundation is located above the tunnel roof; The influence of the pile group on the tunnel lining and the displacement can be minimized when the pile foundation is extended below the failure surface of the sidewall and the pile foundation adjacent to the side wall is extended below the tunnel floor. 

Key words: pile group foundation, station tunnel, pile length, inner force of lining, finite element analysis