Influences Research Of Shallow Buried Tunnel Passing Alongside The Existing Bridge Pile

With the continuous improvement of China's economy,the pace of railway construction to speed up,tunnel construction is gradually increasing and playing an important role.The increase of tunnel engineering makes the new tunnel will inevitably pass through the existing tunnel and underground engineering,while the tunnel pass through the existing highway bridge,tunnel excavation will inevitably lead to the loss of strata,thus disturbing the original surrounding rock and destroying the original stress balance,the interaction between the pile and soil changes,resulting in displacement and additional internal force of the bridge,affecting the upper structure of the bridge,thus affecting the normal operation of the expressway,and even cause serious damage to the existing expressway,leading to safety accidents and economic losses.Therefore,it is of great practical significance to study the influence of tunnel construction on strata and bridge.This paper relies on the Wenbishan tunnel engineering pass through Changshen expressway bridge,the average depth of the tunnel is only 3 ~ 4m,the horizontal clearance of tunnel and expressway pile is 8m,auxiliary measures of advanced small pipe grouting and isolation pile is adopted to help construction,of which has a certain effect on the bridge.The main research contents are:(1)Theoretical analysis,introduces the basic theory of the strata formation caused by tunnel excavation and influence of strata movement on the bridge,tunnel and bridge that is a process of mutual influence.(2)Numerical simulation,the finite element software Midas-GTS is used to analyze the effects of tunnel construction on surface subsidence,horizontal displacement and vertical displacement of strata,displacement of beam structure,displacement of piers,displacement of the pile foundation and the effect of stress.(3)On-site measurement,the monitoring points were layouted at the construction site,the data were collected,the measured data were sorted out and compared with the results obtained by numerical simulation,surface subsidence and displacement of pier top were compared to validate the correctness of the simulated calculation,analyze the differences and possible reasons.