基于应变梯度理论的分区破裂机制分析研究

 随着地下工程开挖深度的增加，深部洞室围岩中将出现与浅埋洞室破坏模式迥异的分区破裂现象。为进一步研究分区破裂现象的形成机制，基于应变梯度理论和连续损伤力学建立分区破裂弹性损伤软化模型，推导考虑平面外应力影响的准平面应变问题的平衡方程和边界条件，应用Matlab求得深部洞室围岩中径向位移、径向应变和应力的波峰和波谷交替出现的振荡型变化规律。理论计算值与地质力学模型试验实测值在量值与变化规律两方面均符合较好，这证实了分区破裂弹性损伤软化模型在解释深部岩体分区破裂问题中的适用性。深部洞室围岩中应力场的波峰和波谷交替出现的振荡型变化规律是导致分区破裂现象出现的关键原因。

Zonal disintegration mechanism based on strain gradient theory

With the increase of excavation depth，the zonal disintegration phenomenon in surrounding rock of deep cavern appears，which is quite different from the failure mode of shallow cavity. In order to further study the mechanism of zonal disintegration，an elastic damage softening model for zonal disintegration was put forward based on the strain gradient theory and continuum damage mechanics. The equilibrium equations and boundary conditions of quasi-plane strain problem were deduced considering the out-of-plane stress influence. The numerical solutions of radial displacement and radial strain and stresses in deep surrounding rockmass were calculated using Matlab. The numerical solutions presented an oscillation mode. The theoretical calculated values are in good agreement with the model test data. The applicability of elastic damage softening model for zonal disintegration in the explanation of zonal disintegration was confirmed. The oscillation mode of stress in deep surrounding rock is the critical reason for the formation of zonal disintegration.