Research On The Stress Mechanism Of Tunnel Transverse Underneath Cross Landslide And Safe Distance

When the tunnel is unable to avoid landslide because of the objective reasons limit of the line,landslides must be through landslide area in the form of three-dimensional,then the tunnel-landslide system is formed.Tunnel could cross the landslide above or below the sliding zone,and in the sliding zone,and the best way is below the sliding zone,which tunnel underneath pass landslide system is formed.In this system,the force condition of tunnel vault and side wall,the suitable distance between tunnel and slide zone become the key problem.If the distance is too small,tunnel will be damaged by the sliding of landslide,or which is too large,that can cause unnecessary waste.The tunnel-landslide system typical worksite were analyzed in this article,the tunnel-mechanical calculation model of landslide was puts forward,the main influencing factors for stress of tunnel were researched by numerical simulation and model test.The force of tunnel vault and side wall were analyzed by the combination of Theory of geotechnical mechanics and landslide.The minimum safe distance calculation formula was deduced,The Mechanical analysis and the numerical simulation were work for tunnel in Qinghai province and Chongqing Yanjiangwan tunnel,the stress change of tunnel vault and the development process were further studied,and the Minimum safe distance was calculated.Research results are as follows:(1)Investigation and analysis the typical works of the tunnel under the landslide,This paper summarizes the typical geological model of the tunnel under the landslide。(2)The five main factors influencing of tunnel stress were simulation by FLAC3 D software,they are the location of crossing,the distance between sliding surface and the tunnel,the Angle of sliding surface,rock type and excavation method,and the conclusion are as follow,when the tunnel is obtained through the landslide trailing edge than from main sliding section of force and deformation under across,when tunnel and the closer distance sliding surface,sliding surface inclination,the greater the grade of surrounding rock is lower,the greater the stress of the tunnel.(3)The model test was completed which Yangjiawan tunnel landslide was as prototype,a typical cross section of the Yangjiawan tunnel-landslide is was to simulate,the stress change of tunnel vault and side wall were analyzed.(4)The mechanics of tunnel landslide model was analyzed,the force calculation formula for tunnel-landslide system of tunnel vault and sidewall was derived,and the minimum safety of tunnel-landslide system distance was obtained.(5)The tunnel-landslide system in Qinghai province was researched,and Mechanism of deformation failure of the tunnel was analyzed.