陡倾小交角层状围岩浅埋隧道锚杆支护优化研究

Study on Optimization of Bolt Support of Shallow Tunnel in Sub-vertical Layered Rock Small Angle Intersecting

陡倾小交角层状围岩隧道指隧道轴线与岩层走向一致或小角度相交(一般小于20°),且岩层倾角较大(一般大于40°)的隧道。开挖施工时其层状岩体容易沿层面发生顺层滑移从而引发灾害。目前,隧道开挖使用的锚杆支护结构多沿隧道轮廓线径向布置,而且在隧道横断面上左右对称布置,该锚杆支护结构不适应陡倾小交角层状围岩隧道围岩的破坏机制。针对陡倾小交角层状岩体隧道的地质特征和破坏机制,对其锚杆支护结构系统进行了优化分析,提出了一种适用性更强的锚杆支护系统,该支护结构沿隧道洞周采用非对称非均长布置,能防止围岩发生顺层滑移破坏,有效地控制围岩变形,从而降低隧道开挖施工的风险和费用。

When a tunnel's axis is the same as rock layer trend or the intersection angle is small( < 20°),and the inclination of rock layer is comparatively large( > 40°),it is easy leading to a disaster that rock layer slipping along the level in the process of excavation. Currently,most bolting structure are arranged radially along the tunnel contour,and all symmetrically on cross-section,but it is not fit to the failure mechanism of the tunnel in layered rock which is sub-vertical with and small angle intersecting. After analyzing the geological characteristics and failure mechanism,we optimized the bolt supporting structure,and proposed a new bolt supporting system which was more adaptable. The bolts are arranged unsymmetrically and different in length around the tunnel contour. This new supporting structure can prevent bedding-slip of the surrounding rock,and control the deformation of surrounding rock effectively. So,the risk and cost of tunnel excavation will be reduced.