Study On Landslide Stability Under Tunnel Crossing Conditions

With the development of national economy,a new round of large-scale construction is coming in China.More and more traffic tunnels are built in the mountainous areas of central and Western China.The terrain and geological conditions in these areas are complex.Highway and railway tunnels often need to pass through unfavorable geological areas.In the process of tunnel construction and later operation,landslides and other geological hazards will inevitably affect them.At the same time,in the process of tunnel construction,it is inevitable to disturb the slope,even if the landslide body has not fully developed in the initial stage of tunnel construction.However,due to the construction disturbance during the tunnel construction process and the influence of rain,earthquake and train load in the operation process,the original stable landslide may also produce landslides,resulting in huge losses.Based on the theory of point safety factor,this paper mainly studies the influence of tunnel excavation and train load on landslide stability.The main research contents and conclusions are as follows:(1)Aiming at the calculation model and similar model(excavating small tunnels in large landslide model),tunnel excavation has little influence on the overall stability of landslide,but it may have a greater impact on the local stability of landslide(depending on the location of the landslide where the tunnel is located);train load has a greater impact on the calculation results of the safety factor of landslide points below the tunnel.(2)When the tunnel is excavated in the middle and rear part of the landslide,because of the shallow buried depth of the tunnel and the smaller overlying pressure,the excavation will not have a greater impact on the landslide;but when the tunnel is excavated in the front part of the landslide,because of the large buried depth of the tunnel,the excavation will have a greater impact on the local stability of the sliding zone at the top of the tunnel,and the point safety factor will decrease significantly,and the local stability will be reduced to less than 1.05,acording to the relevant specifications [43],the position is in an unstable state.(3)When the tunnel is located in the middle and rear part of the landslide,the contour of the safety factor of the landslide point is obviously lower than that of the original and excavated results,because the influence of train load on the calculation results of the safety factor of the landslide point is larger.(4)Grouting reinforcement has obvious effect on improving the local stability of landslide.Anti-slide pile reinforcement has obvious effect on improving the overall stability of landslide under tunnel,but it can not solve the problem that the safety factor of local points decreases obviously due to excavation.