Influence Of Side-crossing Bridge On Pile Foundation Of Double-Line Shield Tunnel And Control Measures

The development of underground traffic has brought new convenience for people to travel,but at the same time,the influence of underground engineering on the environment can not be ignored in the process of construction.The construction of tunnel is not only a long construction period,but also the construction process is more tedious.The prediction of tunnel construction process is also an important part of underground construction project.Therefore,this paper mainly discusses the displacement change of surface and bridge pile foundation during the construction of double-wire shield tunnel,and studies the change of internal force of pile foundation.The concrete contents are as follows:(1)This paper summarizes the variation law of surface,building and bridge pile foundation caused by tunnel construction,expounds the working principle of shield tunnel construction,and analyzes the causes of deformation of ground surface and pile foundation during shield tunnel construction,and analyzes the causes of deformation of ground surface and pile foundation during the construction of shield tunnel,based on the analysis of the working principle of shield tunnel construction.It provides a theoretical basis for the construction simulation of shield tunnel.(2)According to the actual project of the section of the construction of the Beijing Metro Line 16 civil engineering construction,the contract section of the Yong ding River is used to simulate the tunnel construction process of the double-line shield tunnel by using the MIDAS GTS NX finite element analysis software.The ground settlement caused by the ground and the displacement and internal force of the bridge pile are analyzed and compared with the monitoring points.The results show that the surface settlement trend shows a "V" shape distribution,and the settlement value is the largest at the center of the two tunnels,and the settlement value decreases gradually toward both sides.The lateral displacement of each pile gradually increases with the offset of the tunnel construction process,and the deviation at the top of the displacement pile>pile body>the bottom of the pile,the trend of the vertical displacement curve is about the same.When the tunnel starts to excavate,the displacement value of the pile bottom increases instantaneously and then gradually decreases.When the tunnel is excavated to different distances,the pile foundation is different.The difference between the axial force values is very small,and the axial force of the pile foundation has the same trend,which tends to decrease with the tunnel excavation.The axial force values of the piles are almost coincident along the pile body distribution,and the axial force values are along the pile.The top and bottom are first increased and then decreased,and the bending moments are distributed along the pile body.The same as the pile foundation depth increases first,then decreases and then increases.(3)Combined with the existing measures to strengthen the bridge pile foundation,this paper provides two schemes for the reinforcement of the pile and the pile side composite anchor bolt grouting,and simulates the construction stage of the two schemes by using MIDAS GTS NX,and through the lateral displacement of the pile foundation,On the basis of comparative analysis of vertical displacement,axial force and bending moment,pile lateral reinforcement is more effective than pile-to-pile reinforcement for bridge pile foundation in this project.Through the simulation research on the construction stage of the double-track tunnel,it can provide theoretical experience for similar engineering cases,and provide some reference for the selection of bridge reinforcement measures.