Research On Pavement Settlement Control Technology Of Tunnel Under Passing Existing Expressway

Wanrong tunnel in Wanrong County,Yuncheng City,Shanxi Province,it under crossing the wen he expressway in the DK557+222~DK557+248 section.The soil body is sandy old loess and fine sand in this region,the surrounding rock level is lower,it is V class surrounding rock.This paper uses FLAC~3DD numerical simulation software,in order to reduce the degree of deformation of the tunnel under crossing the highway subgrade,numerical simulation is carried out for the optimization research of advance support measures and construction plans for the under crossing tunnel.In this paper,the advance support measures are comparatively analyzed with unreinforced scheme by main respectively using three kinds of advance support methods,such as small pipe grouting reinforcement,single pipe shed+small pipe grouting reinforcement and double-layer pipe shed+small pipe grouting reinforcement.The construction methods are comparatively analyzed by main respectively using three kinds of methods,such as three steps seven footwork,CD method and double side wall method.The main research contents of this paper include the displacement around the tunnel,the principal stress of preliminary bracing,and the surface settlement at the roadbed and so on.The conclusion is that the plan of double tube shed+small pipe grouting advance support measures,three steps seven footwork construction plan should be adopted to reduce the degree of deformation of the tunnel under crossing the highway subgrade in this project.The conclusion can provide useful reference for the design,construction and research of similar tunnel under crossing the highway.