考虑岩体塑性硬化与软化特性的巷道围岩变形理论分析

为深入探究岩石峰值强度前后非线性硬化与非线性软化特性对软岩巷道围岩变形及力学行为的影响,引入硬化系数与软化系数的概念,基于莫尔-库仑屈服准则与非关联流动法则,推导出圆形巷道围岩四区应力、位移和半径的解析表达式。通过算例,分析了硬化系数和软化系数对塑性硬化区与塑性软化区巷道围岩的影响。结果表明:对于巷道围岩塑性硬化区,其径向与切向应力随内摩擦角、黏聚力硬化系数的增大而增大,径向与切向应变也随内摩擦角硬化系数的增大而增大;而对于塑性软化区,其径向与切向应力随内摩擦角、黏聚力软化系数的增大而减小,径向与切向应变也随内摩擦角软化系数的增大而减小。因此提高巷道围岩塑性硬化区的内摩擦角、黏聚力硬化系数与降低塑性软化区的内摩擦角、黏聚力软化系数可提高围岩承载能力。

Theoretical analysis on roadway surrounding rock deformation based on the properties of rock plastic hardening and softening

In order to investigate the influence of nonlinear hardening and softening，which are encountered near the peak strength，on the roadway deformation and mechanical behaviors，hardening and softening coefficients were introduced.Based on Mohr-Coulomb Criterion and non-associated flow rule，the analytical expressions of stress，displacement and the corresponding radius in surrounding rocks of circular roadways were proposed.The influence of hardening and softening coefficients on the surrounding rocks located in the plastic-hardening zone and plastic-softening zone were investigated by case study.Corresponding results can be summarized as follows:initially，the stresses and strains in radial and tangential directions will increase as the hardening coefficients of internal friction angle and cohesion increase in the plastic-hardening zone；however，the radial stress and tangential stress will decrease as the hardening coefficients of internal friction angle and cohesion increase in the plastic-softening zone；furthermore，the radial and tangential strain will decrease with the increase of softening coefficient of internal friction angle.It can be concluded that the bearing capability of surrounding rock can be improved by increasing the hardening coefficients of internal friction angle and cohesion in plastic-hardening zone and decreasing the hardening coefficients of internal friction angle and cohesion in plastic-softening zone.