基于Hoek-Brown强度准则及量化GSI围岩评级系统,分析岩体强度弱化行为,总结出确定岩体峰值及峰后强度参数的方法,提出应变软化模型的简化计算方法,并以FLAC3D数值模拟软件为工具,采用收敛-约束法对深埋大断面隧道支护结构及围岩稳定性进行分析,计算出支护结构安全系数。通过分析得出:随着围岩应力释放,岩体软化参数随之减小,岩体强度弱化行为突出;高地质强度GSI指标(GSI=75)的岩体虽然强度弱化程度较大,但围岩的变形量仍然较小,而低GSI指标(GSI=25)的岩体表现出了理想弹塑性行为;提出的简化Hoek-Brown应变软化模型适合应用于隧道中岩质相近区段围岩的研究;采用收敛-约束法对隧道支护结构的稳定性进行分析,可为隧道工程的初期支护优化设计及安全性评价提供参考。 Based on the Hoek-Brown strength criterion and the quantified GSI surrounding rock grading system, the weakening behavior of rock mass is analyzed, and the method of determining the peak and post-peak strength parameters of the rock mass is concluded. A simplified calculation method of strain softening model is proposed. The FLAC3D numerical simulation software As a tool, the convergence and restraint method is adopted to analyze the stability of the surrounding rock of the deep large section tunnel and calculate the safety factor of the supporting structure. The analysis results show that with the release of surrounding rock stress, the rock mass softening parameters decrease and the rock mass strength weakens well. The rock mass with high geological intensity GSI index (GSI = 75) The deformation of rock is still small, while the rock mass with low GSI index (GSI = 25) shows the ideal elastoplastic behavior. The simplified Hoek-Brown strain softening model proposed is suitable for the application of surrounding rocks with similar rock mass in the tunnel The analysis of the stability of the tunnel support structure using the convergence-restraint method can provide reference for the optimization design and safety evaluation of the initial support of the tunnel project.