考虑非线性脆性损伤和中间主应力影响的圆形巷道围岩分析

针对岩石的脆性破坏特征及峰后力学性能的劣化损伤,引入非线性脆性损伤本构模型,得到三维连续损伤演化方程。将圆形巷道围岩划分为松动破裂区、脆性损伤区、弹性区,考虑中间主应力的作用,采用统一强度准则和连续损伤力学方法,对巷道围岩力学状态进行极限平衡分析,推导出围岩损伤破裂半径及应力场分布的解析表达式。通过算例,分析了中间主应力、围岩脆性特征和损伤程度对理论解的影响。分析表明:中间主应力作用越大,围岩的损伤破裂半径越小,切向应力峰值距离巷道越近;脆性强弱对围岩应力分布的影响只局限在脆性损伤区内,围岩的脆性越强,损伤破裂半径越大,脆性损伤区内的切向应力随深度的增大而增大;围岩的残余强度越小,松动破裂程度越大,损伤破裂半径越大,切向应力峰值向围岩深部转移。

Analysis on surrounding rock of circular roadway considering nonlinear brittle damage and intermediate principal stress

Considering the brittle failure characteristics and the mechanical properties deterioration after post-peak of rock，a 3-dimensional continuum damage evolution equation was derived by introducing a nonlinear damage constitutive model for brittle rock.The circular roadway surrounding rock was divided into loose cracked zone，brittle damage zone and elastic zone.Considering the effect of intermediate principal stress，the unified strength criterion and continuum damage mechanics were used to analyze the mechanical states of roadway surrounding rock through limit equilibrium analysis method.Then，the analytic expression of damaged and cracked radius and stress distribution of surrounding rock were deduced.In the case studies，the effect of intermediate principal stress，rock brittleness and damage degree on analytical solution were analyzed.The results show that the bigger the intermediate principal stress effect is，the bigger damaged and cracked radius will be，and the peak of tangential stress will be closer to roadway;the effect of brittleness on stress distribution is confined to brittle damage zone，the more strong the brittleness is，the bigger damage and fracture radius will be，and the increment of tangential stress with depth is larger in brittle damage zone;the smaller the residual strength is，the bigger cracked degree and radius will be，and the peak of tangential stress will move to the deep surrounding rock.