Study On The Numerical Simulation Of Shield Tunneling Under An Arch Bridge And Safety Measures

Tunnel shield method has been the main method of metro construction.With the expansion of subway construction,the problems faced by shield tunneling has become more and more complicated.Chengdu Metro Line 5 is faced with the problem of tunneling under an arch bridge during construction.It can not be avoid that the process will cause disturbance on the foundation,while the bridge is very demanding on the stability of the foundation.The research on such problems is scarce at home.The numerical simulation is an important means to study the problem of adjacent construction.An effective research must be based on the correction of numerical simulation of shield tunneling.While the process itself is very complicated,making it hard for a correct simulation.In view of the above problems,this paper,based on the project example of shield tunneling under the Xibei bridge,uses the means of consulting literature and numerical simulation,and mainly carries out the following research,which includes:(1)The factors required for a numerical simulation such as face pressure,cutter torque,shield model,shield clearance,shield tail grouting,jacking force,segment lining,trailer load and other factors,and their implementation methods for the numerical simulation.(2)A numerical model of EPB shield tunneling in sandy cobble stratum is established,and the importance of friction contact between shield and soil is analyzed.(3)A numerical model for the shield tunneling under Xibei bridge is established,and the influence factors such as foundation settlement,bearing displacement and internal force of archs are analyzed.(4)The internal arch reinforcement method adopted in the project is analyzed,and its reinforcement effect,internal force and reinforcement are evaluated.Its reinforcement effect and reinforcement of different thickness are studied.