Study On The Optimization And Numerical Analysis Of The Strong Weathering Shale Shallow Bias Tunnel Support Measures

With the development of social production, the highway is increasing year by year, it requires the straight gentle lines and spacious road, when it crosses mountain area,the plan of highway tunnel usually will be used. Shallow bias tunnel is a kind of form in Tunnel Engineering, it often appears at points where the lines cross the terrain contour or near the river. This tunnel always has low rock strength, poor stability, developed rock fissures,relatively loose and broken rock mass, even accompanied by a certain degree of surface water seepage etc. This paper regards Sha Zipo tunnel as a research object which is built in highway engineering from Long Shan to Yong Shun,the author choose the shallow bias tunnel entrance section which is located in the strong weathering period to make numerical simulation and optimization analysis, the main contents are as follows:(1) According to the Sha Zipo tunnel geological survey report and risk assessment, this paper expounds its geology environment and weak surrounding rock section; understands the reasonable use of the importance of the supporting structure system to ensure the safety of construction smoothly, and selects the corresponding supporting structure and supporting parameters for the tunnel support in supporting system in the preliminary design.(2) The author summaries the different function and suitable characteristics of the supporting structure in tunnel surrounding rock. Forepole, primary support and secondary lining themselves have special roles offering important effects, but need be designed more.(3) This paper uses FLAC3 D finite difference software to make a numerical simulation on the strongly weathered shale hole shallow bias section; respectively analysis the supporting structure mechanical characteristics and the stress field, displacement field of the surrounding rock; and then analysis the stability of the tunnel in both cases the natural state and rainfall condition without supporting structure; the applicability of tunnel supporting measures in full face excavation method and CRD excavation method. Finally summarizes, the selection of supporting measures guarantee the stability of the tunnel.