基于块体和松动压力理论的隧洞围岩稳定性分析

Analysis on Stability of the Surrounding Rock in Tunnel Based on Block and Loose Pressure Theory

岩体中开挖隧洞的围岩失稳形式较多,尤其在埋深浅、应力低、结构面发育的地质区域经常出现顶部垮塌和边墙滑动失稳现象。笔者以某导流隧洞为工程背景,基于块体理论,运用Unwedge程序以不同隧洞走向和不同开挖断面形式条件下搜索出的关键块体重量和安全系数为研究目标,通过对比优选出适合本区域内导流洞围岩稳定的理论轴线走向和断面形式,为设计单位提供理论支撑。同时,对主次节理高度发育、围岩破碎严重、不适于用Unwedge程序进行计算的区域应用松动压力理论对围岩稳定进行计算并给出支护建议。

There are many instability forms of surrounding rock in the underground excavation,particularly,in the geological areas with shallow buried depth,low stress and developed structural plane,there always appear instability phenomena of the roof collapse and wall sliding. This paper takes a tunnel as example,based on the theory of block and using Unwedge program in the weight of key block and the factor of safety as the research target under different trend of tunnel and different excavation forms of cross section,the optimal trend of tunnel and reasonable excavation forms have been analyzed by comparing the optimization in the diversion tunnel,to some extent,provides theoretical reference for the design. Meanwhile,the regions where the primary and secondary joint are highly developed,the surrounding rock is broken seriously and which are not suitable for calculation by using Unwedge program,the stability of surrounding rock is calculated by using loose pressure theory in these regions and reasonable supporting recommendations are proposed.