Research On The Influence Of Shield Tunneling To Neighboring Pile Foundation

With China’s accelerated urbanization, the city available land decreased very quickly. In order to satisfy the citizens’ travel demand,more and more cities began to build the subway. Compared to the traditional metro construction, shield method has its unique advantages so that which has become the main method of metro tunnel construction. Although the shield method has achieved great development, it still causes strata displacement and ground subsidence.When the soil deformation caused by shield tunneling over a certain extent, it will produce a big impact to the pile foundation of buildings.With MIDAS/GTS numerical simulation method,this paper has made an research of the ground subsidence due to shield tunneling,and discusses the deformation of single pile and pile group induced by shield tunneling, finally get the deformation rule of pile foundation during shield tunneling process.By using the finite element software MIDAS/GTS to make a numerical simulation of shield tunnel crossing neighboring single pile, pile with different length and position due to the impact caused by the shield tunnelling are analyzed in this paper. Results show that:(1) During tunneling, the ground surface settlement trough shape is similar to the Gauss distribution curve.(2)The major deformation form of short pile is incline during tunneling. For the long pile, bend is the major form.(3) The pile length influence the deformation of a pile observably, especially when the pile end is under the depth of tunnel buried.(4)The farther the distance between single pile and tunnel, the smaller the maximum axial force and maximum bending moment of the single pile. When the distance between them reached a certain degree(12m in this paper), axial force and bending moment of the pile can be neglected.The results of numerical analysis on influence of shield tunneling to neighboring pile group show that:(1) the deformation and internal force of piles in the front row were bigger than those in back row. As piles located in the same row, the changes of horizontal displacement, axial force and bending moment are basically same.(2) The horizontal displacement of pile in groups is slightly bigger than single pile at the same location,and the settlement of the pile in the groups is slightly smaller.(3) The maximum bending moment of pile in groups compared with those of single pile at the same location, were basically same, and maximum axial force of pile in groups isslightly smaller.