隧道-洞口滑坡体系受力特征及变形模式

Stress distribution and deformation model of the tunnel and landslide at the tunnel’s entrance

随着我国高速铁路在西部地区的大规模建设,隧道在线路中所占的比例越来越高,洞口隧道在滑坡作用下产生的病害越来越严重。然而,我国目前在隧道-洞口滑坡体系设计中没有可供参考的受力变形模式,因此本文以隧道-洞口滑坡为研究对象,通过对云南功东高速公路中隧道-滑坡工程实例的总结及工程地质模型的建立,对滑坡推力作用下的隧道变形模式进行研究,得到如下结论:(1)将隧道-洞口滑坡分为与滑面相交和下穿滑体两种模式,与滑面相交的隧道直接受到剩余滑坡推力的作用,而下穿滑体的隧道主要承受附加荷载的影响;(2)位于滑体内隧道承受围岩压力、滑坡推力和岩土抗力的作用,可将洞口有刚性支撑的隧道-滑坡结构简化为简支梁,无刚性支撑作用下的隧道-滑坡结构简化为悬臂梁;(3)下穿滑体隧道在附加荷载的影响下,拱部承受多余的压力而受到偏压作用,拱顶形成受拉区域,出现拉张裂缝。

With the large-scale construction of China’s expressway in the western region,more and more tunnels were constructed,and the threat caused by landslide is becoming more and more serious in the tunnel.However,there is no stress and deformation model in the design of tunnel and landslide in the tunnel ’s entrance at present. Taking tunnels in Gongdong Expressway in Yunnan Province,this paper studied the tunnel deformation mode under the effect of landslide thrust. The following conclusions are obtained:( 1) The system of tunnel and landslide in the tunnel’s entrance is divided into two modes,that are intersecting the sliding surface and traversing the lower slide mass. The tunnel intersected with the sliding surface is directly affected by the residual landslide thrust,while the tunnel under the slide mass is mainly affected by the additional load.( 2) The tunnel in the slide mass bears the pressure of the surrounding rock,the residual landslide thrust and the resistance of rock and soil mass. The tunnel-landslide structure with rigid support at the entrance can be simplified as simply supported beam,and the structure without rigid support can be simplified as cantilever beam.( 3) Under the influence of additional load,the arch is subjected to bias action due to bearing excessive load,and the vault forms a tension region and appears tensile crack.