Analysis On The Influence Of Two-line Shield Tunnel Construction On Pile Foundation Under Different Influencing Factors

Shield construction has obvious advantages in tunnel construction,but it will still have an impact on the surrounding environment in construction.In the course of tunnel construction,the pile foundation of the building or structure around the tunnel will be affected by two times after the shield structure,which increases the influence degree of the pile Foundation,and then affects the safe use of the superstructure.Based on the two phase of Zhengzhou Rail Transit Line 2,Tianyuan Road station to JINDA Street station,the shield tunnel undergoes the construction of the center pile foundation of Henan automobile trade center.The construction process of pile foundation under shield is numerically simulated by GTS NX software,and the influence law of double-line tunnel construction on pile foundation deformation and internal force change under different influencing factors is analyzed.The conclusions of the numerical analysis are as follows:(1)In the process of construction approaching pile foundation,shield structure will have different influence on pile foundation in different stages.The stage before the shield reaches the pile foundation will cause the pile foundation to move upward,which has the greatest influence on the pile foundation when it passes through the pile foundation.(2)The influence of different construction sequence and different construction error distance on the pile foundation is very small.In actual engineering,the construction and distance adjustment of the tunnel can be carried out according to the needs of the scene.(3)Within the range of pile foundation length,with the deepening of tunnel burial,the horizontal displacement of piles caused by successive construction of double-track tunnels increases gradually,while the vertical displacement,additional axial force and additional bending moment decrease gradually.(4)With the increase of the horizontal distance between tunnel and pile foundation(within 1D range),the horizontal displacement,vertical displacement and axial force of pile foundation increase,and the change range of horizontal and vertical displacement decreases gradually,while the additional bending moment of pile is less affected.(5)With the increase of the distance between double-track tunnels(within 1.5D range),the horizontal displacement,vertical displacement and additional axial force of pile foundation decrease correspondingly,but the degree of reduction is small,and the additional bending moment of pile foundation is less affected.