Research on stability control methods for shield tunnels overlapping box culverts under-crossing existing railways
It is crucial to adopt appropriate excavation plans and corresponding reinforcement measures to ensure the stability of the wall rock and settlement deformations of railway roadbeds within an allowable range during shield tunnel and box culvert excavation projects.To this end,based on Xiamen metro line 6 and with the help of finite difference software FLAC3D as well as on-site monitoring data,the structure characteristic positions,ground and railway roadbed deformations and reinforcement measures of tunnels overlapping box culverts and underpassing existing railways under various construction conditions were analyzed.In doing so,the following conclusions were obtained:(1)By conducting in-depth research on the structure characteristic positions and surface displacement of tunnels and box culverts,the optimal excavation plan was determined.This plan involves box culvert excavation first,followed by shield driving on the right side of the support structure before tunneling on the left side.(2)When the surrounding rock and roadbed lack reinforcement and the box culvert experiences active failure,the deformation may extend to the ground level.After reinforcement,the damaged soil near the heading face of the shield tunnel and box culvert gradually transitions to occurring solely in front of the heading face and does not propagate upwards.(3)On-site monitoring data shows that ground displacement,tunnel arch top and box culvert top displacement all show a gradually increasing trend over time.Meanwhile,the convergence of tunnel clearance does not show any significant changes,and the stress monitoring values of tunnel and box culvert heading face supporting forces fluctuate within a certain range.Upon comparing these with the numerical results,it was found that the values align well with the on-site measured results.
tunnel engineeringbox culvert installationrailway roadbedstabilitysupporting force
NETL
NSTL
万方数据
维普
