深部硬岩二次应力状态下破裂的断裂力学分析

 为探索深部硬岩的开挖扰动对微裂纹延展破坏的影响关系,利用弹性力学与断裂力学相结合的理论分析方法,依据弹塑性力学的应力分解叠加等效原则和断裂力学的最大周向拉应力准则,求解出不同侧压力系数λ条件下深部巷道围岩的二次应力解析解,并推导出了极限状态下裂纹扩展长度的理论计算公式。通过建立岩石断裂力学参数模型分析发现,侧压系数λ对巷道破坏深度和周边应力场分布有着明显的影响。λ＞1时,边帮为裂纹延展破坏的主要区域,λ＜1时,顶底板为裂纹延展破坏的主要区域;在压剪应力方向一定时,裂纹延展深度与裂纹初始长度有关,与应力大小无关。

Fracture Mechanics Analysis of Fracture Zone in Deep Hard Rock Under the State of Secondary Stresses

In order to explore the impact of the excavation disturbance on the microcrack extension, by using the combining method of elasticity and fracture mechanics, the analytic solution of the secondary stress for the lateral pressure coefficient λ is obtained based on the decomposition and superposition principles. The formulas for the extending depth of the fissure cracking are derived according to the maximum circumferential stress criterion. By building series of models of rock mechanics parameters, it is shown that the lateral pressure coefficient λ has a significant effect on the failure depth of the roadway and the stress distribution. The roadway's sides are the main regions of the surrounding rock failure under the condition of λ＞1, the roof and the floor are the main regions of the nsurrounding rock failure under the condition of λ＜1. In addition, the failure depth of the roadway has no correlation with the magnitude of the stress under a constant compression-shear stress, but dependent on the crack initial length.