裂纹尖端屈服条件下的围岩劈裂破坏判据研究

Study on Splitting Failure Criterion of Surrounding Rock under Point Yield

针对裂纹尖端附近出现塑性区时线弹性断裂力学理论不适用的问题,采用滑移裂纹组模型模拟岩石在轴向压力下的劈裂破坏,根据Mises屈服准则求出塑性区半径和整个体积中塑性变形引起的耗散能,基于能量平衡原理得到小范围屈服条件下的劈裂判据,将该判据应用于琅琊山抽水蓄能水电站机组的开挖分析中,计算获得了劈裂破坏区范围分布图,并与Lajtai经验公式进行比较,结果较为一致,表明该方法可行、有效,为地下工程开挖引起的劈裂破坏提供了预测判据。

The new fracture criterion is set up because the elastic fracture mechanics is not applicable for the plastic zone. Considering the interaction among cracks, the sliding multi-cracks model is adopted to simulate the splitting failure of rock in axial pressure. The plastic radius is calculated by Mises yield criterion and the dissipation energy for plastic deformation in total volume is also computed. The splitting failure criterion is established with principle of energy balance. The criterion is applied to the excavation of Langyashan pumped storage power station. The distribution charts of splitting failure zone are obtained, which coincides with results obtained by Lajtai empirical formula. It shows that the method is effective and feasible, which provides prediction criterion for splitting failure of underground engineering excavation in high geostress.