Based on the nonlinear strength criterion, Hoek-Brown strength criterion, the rules of variation of the rock mass strength in the rock wall after the stress redistribution caused by excavation unloading is analyzed. Conclusions can be drawn as follows; because of the unloading process, the strength of rock mass reduced always. The reduce value is differential in different district. The strength of rock mass shows decrease trend with the decrease of GSI and rock uniaxial compress strength crci, increase trend with the decrease of disturbance degree D.%基于非线性Hoek-Brown强度准则,对地下岩体开挖应力重分布后岩体强度的变化规律进行了研究.结果表明,由于应力卸荷洞周一定范围岩体强度发生明显降低,不同部位降低幅值不同,距洞壁位置越远降低越小.岩体表征参数GSI、单轴抗压强度σci降低,卸荷后岩体强度降低,应力扰动系数D降低,岩体强度升高.
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