Numerical Simulation Of The Impact Of Shield Tu Nneling On Adjacent Pile Foundation

Based on the shield tunnel of Hefei Metro Line 2 shield through the Wulidun overpass pile group,the finite difference software MIDAS/GTS was used to establish the three-dimensional numerical model to analyze the law of displacement deformation and internal force variation of pile foundation under different working conditions of double-line tunnel.And combined with theoretical analysis and field monitoring data for comparative analysis,the research work and conclusions are as follows:(1)Domestic and foreign scholars on the shield tunnel through the building of the relevant research methods and content were analyzed,as well as the safe construction of the project control measures were guaranteed.Then the influence factors of pile foundation deformation and surface settlement during shield through the bridge pile were summarized.The mechanism and regularity of surface settlement and pile foundation deformation caused by tunnel excavation were analyzed.(2)Through the monitoring data of the tunnel pile foundation,the numerical simulation results are smaller than the actual measurements.However,the numerical simulation can better reflect the displacement deformation and internal force variation of the pile foundation.(3)In the process of shield tunneling,the settlement of surrounding soil is much larger than that of pile tip settlement,the trend of settlement change is basically the same.The lateral horizontal displacement and longitudinal horizontal displacement of the distance between the pile body and the tail are first increased and then decreased,the maximum lateral displacement occurred in the pile depth of 8m,the maximum longitudinal displacement is located at 13 m depth of the pile.(4)The change trend of pile shaft force,shear force and bending moment is closely related to the tunnel shield construction condition,the tunnel shield tunneling interferes with the surrounding soil,and the axial force of the pile is maximized under the influence of construction factors.With the continuous tunneling of the shield,the surrounding soil is subsiding,and the soil is acting on the lateral friction of the pile,and the axial force of the pile is decreasing continuously.The curves of shear and bending moment have inflection points.