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首先建立双向压缩条件下形成单一闭合裂纹的力学模型,考虑摩擦力的影响,计算出裂纹面的正应力和剪应力。分别运用有效剪应力准则和最大周向应力准则计算裂纹的初始断裂角。运用有效剪应力准则得出的初始断裂角只与岩石的抗拉强度和抗压强度之比有关。运用最大周向应力准则得出的初始断裂角受裂纹和荷载方向的夹角、裂纹面之间的摩擦系数、侧压力系数的影响。将两种理论分析的结果与实验结果进行对比分析得出:考虑摩擦力的最大周向应力准则更接近裂纹扩展的实际情况,建议工程中更多的采用该准则,而有效剪应力准则与实验结果不相符,有待完善。岩石闭合裂纹的扩展及断裂是一个复杂的过程,有待深入分析研究。
Firstly, a mechanical model of single closed crack under bidirectional compression was established. The normal stress and shear stress of the cracked surface were calculated considering the influence of friction. The initial fracture angle of the crack was calculated by using the effective shear stress criterion and the maximum circumferential stress criterion respectively. The initial fracture angle obtained by using the effective shear stress criterion is only related to the ratio of tensile strength and compressive strength of rock. The initial fracture angle obtained from the maximum circumferential stress criterion is affected by the angle between the crack and the load direction, the friction coefficient between the crack surfaces and the lateral pressure coefficient. Comparing the results of the two theoretical analyzes with the experimental results, it is concluded that the maximum circumferential stress criterion considering the friction is closer to the actual situation of the crack propagation. It is suggested that the criterion be adopted more in the project, and the effective shear stress criterion and experiment Results do not match, to be perfected. The expansion and fracture of rock closure cracks are a complex process to be further analyzed and studied.