基于改进Sarma理论的隧道围岩楔形体稳定性计算方法及应用

Calculation Method and Application for Wedge Rock-Mass in Surrounding Rock of Tunnel Based on the Theory of Sarma

隧道围岩楔形体是节理面、软弱夹层或断层等结构面经过切割完整岩体形成的岩石块体,是地下洞室中常见的地质灾害之一。为了量化评价隧道围岩楔形体稳定性情况,基于改进的Sarma理论方法,建立了地下隧洞楔形体计算物理模型及力学模型,推导了楔形体稳定性计算的临界加速度系数,提出了楔形体正压力计算方法,并基于结构面参数给出了楔形体稳定系数计算的隐函数表达式。将此方法应用于粗石山隧道围岩楔形体工程,结果表明,该楔形体稳定系数为1.05,处于欠稳定状态,建议通过采用喷钢纤维混凝土、系统长锚杆、设置格栅钢架等措施提高结构的整体支护能力,加强支护后的位移监测数据表明,该段围岩楔形体变形量很小,围岩整体稳定。

Wedge rock-mass in surrounding rock of tunnel is cut by the joint surface,weak interacted layer or fault,which is one of the common geologic disasters. For the sake of quantitatively evaluating the stability condition of a wedge of surrounding rock,calculation model and mechanics model of Wedge rock-mass in the underground tunnel were proposed based on advanced Sarma method. With iteration and discount stability coefficient of wedge,rock-mass was calculated after critical acceleration coefficient and stability coefficient was deduced and given based on structure surface parameters. The calculation results of the wedge in Cushishan tunnel by use of this method indicated that the stability coefficient of the wedge was 1. 05 and judged the wedge rock-mass to be understated condition. Sprinkling steel fiber reinforced concrete,system bolts and steel frame were suggested to improve the entire supporting capacity. The monitoring result of displacement showed that the displacement of a wedge of surrounding rock was very small,and the surrounding rock was stable.