Study On Effect Of The Existing Pile Foundation Adjacent To Shield Tunneling

The existing buildings and buried pipelines will be inevitably influenced by shield tunneling in urban areas. Especially, due to shield machine approaching and going under piled foundations of buildings, the deformations of soil induced by shield tunneling will occur. Therefore extra inner forces and settlement of a pile will result from the deformations of soil. Accordingly the capacity of the pile will decrease. Hence, accessing the capacity of the pile attracts engineers' and researchers' extensive interests.In this study, the finite difference code FLAC^3D is performed to investigate the influence of shield tunneling on a existing pile. Firstly based on verifying an example, available parameters of materials are put forward to be used in the model. Then responses of a single pile to adjacent a single and double-dube shield tunneling are studied, and some useful conclusions have been obtained. The research in this thesis mainly includes:(1) Considering the different distances between the face of excavation and the pile and the change in thrust of the face of excavation, the skin friction along a pile, settlements of pile cap and the bearing capacity of a single pile which is over and beside the tunnel are analyzed.(2) Taking the different relative spaces between the tunnel and the pile foundation into account, the deformation, internal forces and the bearing capacity of a single pile induced by double-tube shield tunneling are mainly investigated with the different constructing sequences and different distances between the two tunnels.(3) Considering different relative spaces between tunnel and pile foundation, positions of the two overlapped shield tunnels, and different distances between the two tunnels, the deformations and internal forces of a single pile induced by two overlapped tunneling are studied.(4)Some protection measures for pile foundations engineering are summed up, and then grouting method to guarantee the safety of the pile is analyzed using numerical approach. Accordingly, a reasonable protection scheme for the pile is achieved.