基于Hoek-Brown强度准则的大跨连拱隧道围岩稳定性分析

Stability Analysis of the Surrounding Rock of Large-Span Multi-Arch Tunnels Based on the Hoek-Brown Criterion

Hoek-Brown强度准则与Mohr-Coulomb强度准则相比,它综合考虑了岩体结构面特征、岩块强度、施工扰动对岩体的劣化效应的影响,能够很好地反映岩体的非线性破坏特征,更符合工程实际。文章通过数值模拟,分析了地质强度指标GSI、岩块材料常数m i、施工扰动系数D、岩石单轴抗压强度σci对隧道围岩稳定性的影响。分析结果表明:GSI是一个高敏感性参数,其取值直接关系到分析结果的准确性;m i受GSI的影响较大,当GSI大于30时,m i已经不是一个敏感参数;当围岩岩性较差时,施工扰动系数D对拱顶沉降的影响呈抛物线形,随着岩体质量的提高,两者之间趋向于线性关系。

Compared with the Mohr-Coulomb strength criterion, the Hock-Brown strength criterion comprehensively considers more influential factors such as the characteristics of the rock structure surface, rock mass strength, and the deterioration of rock parameters caused by construction disturbances. It can also retlect the nonlinear failure characteristics more accurately, thereby facilitating rock engineering practice much better. Based on numerical simulation, the geology strength index （GSI）, the empirical constant of the rock （mi）, the factor of construction disturbance （D,） and the uniaxial compressive strength of the rock （σci） were analyzed to explore the influence on surrounding rock stability. Conclusions can be drawn as follows： GSI is a highly sensitivity parameter, and its value is directly related to the accuracy of the analysis results; mi is greatly impacted by GSI, and mi is not a sensitive factor if GSI is greater than 30; and the relationship between the construction disturbance factor D and vault settlement is parabolic when the rock is weak, and tends toward a linear relationship with improvement of the rock mass quality. The measures for maintaining rock stability during construction are ultimately discussed.