基于强度折减法判断圆形隧洞围岩稳定性研究

Research on the stability of surrounding rocks of circular tunnel based on the strength reduction method

围绕某圆形隧洞围岩稳定性分析开展了一系列研究。介绍2种基于广义Hoek-Brown准则的强度折减方法,得到了对该准则下相关参数的折减系数;讨论几种岩土工程中常用的失稳判据,并采用圆形隧洞顶部竖向位移发生突变作为失稳判据,并且,引入滑动t-检验方法来确定突变点的位置;由FLAC3D软件建立计算模型,计算隧洞围岩安全系数,并与等效的Mohr-Cou⁃lomb准则强度折减法计算得到的结果进行对比。结果表明:以圆形隧洞顶部竖向位移发生突变作为失稳判据是合理且可行的;通过引入滑动t-检验确定突变点位置的方法提高了计算隧洞稳定安全系数时的客观性和可操作性。

A series of studies have been carried out around the stability analysis of a circular tunnel surrounding rock.Firstly,two strength reduction methods based on generalized Hoek Brown criterion were introduced,and the reduction factors of relevant parameters of the criterion were obtained.Then,several instability criterions commonly used in geotechnical engineering were discussed,and the mutational z-displacement of vault was chosen as the instability criterion.Furthermore,an enhanced criterion using moving t-test method to find the mutation threshold was proposed.Finally,a computational model was built by FLAC3D software to calculate the safety factor of the tunnel envelope and compare it with the results obtained by the equivalent Mohr-Coulomb criterion strength reduction method.The result shows that,using mutational z-displacement of vault as the failure criterion is reasonable and feasible.Besides,the objectivity and operability of calculating tunnel stability safety factor are improved by using moving t-test method to find the mutation threshold.