Study On The Stability Of Surrounding Rock Of Traffic Tunnel Of Longbeiwan Hydropower Station

The region where the highway tunnel is built is the place with complexgeological condition, and the rock lithology strata change greatly. And ground stressconcentration fold belt and fault terrain caused by regional geological structure effectbring the enormous challenges to the tunnel construction and design. The stability ofthe tunnel is influenced by many factors, including the geological conditions,excavation methods and liner form. Therefore, the researches about the surroundingrock deformation and mechanical characteristics under construction state havesignificant value to judge the stability of the surrounding rock, and ensure thesmooth completion of the tunnel. Basic on the traffic tunnel engineering ofLongbeiwan hydropower station, methods including the geological survey and thedisplacement monitoring measurement and numerical simulation are used in thethesis, and make an intensive study on surrounding rock deformation and mechanicalbehavior under construction state, and give the comprehensive evaluation about thesurrounding rock stability of the monitoring sections.The main studies on the thesis are including as following. First of all, the basicinformation of the traffic tunnel and the geological condition are introduced in detail,and make an analysis evaluation about the geological survey results. Then law of thesurrounding rock deformation of K0+20m K0+45m K0+250m and K1+680m underconstruction is monitored, and the monitoring data is processed. Combined with theregression analysis method, the final settlement of vault of K0+20m and K1+680mis forcast, and the value is6.75mm and4.85mm, and the best time to build secondliner is determined. The monitoring sections are simulated by the FLAC^3Dsoftware，the surrounding rock deformation and mechanical characteristic under differentconstruction process and liner form are simulated. In the end, the comprehensiveevaluation is given under two different analysis methods, and the law of thesurrounding rock deformation showing no difference, the total deformation is littleand the deformation rate is slow, so the long-term stability of the tunnel is good. Themonitoring sections are representative, so the laws of the four sections apply to the entire tunnel construction.