脆性材料斜裂纹扩展的数值试验与破坏模式分析

Numerical Test and Failure model Analysis of Inclined Crack Propagation of Brittle Materials

目的分析含斜裂纹脆性材料的破坏过程,研究不同裂纹对脆性材料力学性质的影响,确定斜裂纹的破坏模式.方法利用岩石破裂过程数值分析系统rpfa2D对含一条斜裂纹岩石和三条斜裂纹岩石的破坏过程进行数值试验,应用断裂力学的方法对破坏模式进行理论分析.结果得到了单轴压缩条件下,含一条斜裂纹和三条斜裂纹岩石的整个破坏过程,确定了斜裂纹的破坏模式.结论数值试验的结果表明,单轴压缩条件下三条斜裂纹的扩展,一开始发生在内部裂尖,内部裂尖扩展到临近的预置裂纹之后,外部的裂纹开始扩展;含单裂纹岩石的强度约为三裂纹强度的1.2倍,但三裂纹的残余强度比单裂纹高.数值试验和应力强度因子法得到同样的结论:单轴压缩条件下含一条、三条斜裂纹岩石的初始扩展为压剪破坏,当两裂纹尖端开始扩展之后,形成的翼型裂纹破坏模式为拉剪破坏.笔者提供了一种研究复合型裂纹扩展和断裂破坏模式的新方法.

The numerical tests of failure processes of the rocks with one-inclined-crack and with three-inclined-cracks under uniaxial compression were performed using Rock Failure Process Analysis Code （rpfa2D）. The failure modes are analyzed by method of fracture mechanics. It is concluded that in the case of the rock with three-inclined-cracks under uniaxial compression, the propagation of the inclined cracks initiates from the tips of internal cracks. When the internal cracks propagate and reach the inclined cracks, the corresponding inclined cracks begin to propagate; The strength of the rock with one-inclined-crack was as 1.2 times as that of the rock with three-inclined-cracks, but residual strength of the rock with three-in- clined-cracks was higher than that of the rock with one-inclined-crack. The initiate propagation of the crocks in the cases of both one-inclined-crack and three-inclined-cracks belongs to compression-shearing failure model, and the propagation of the wing cracks formed due to the propagations of the two tips of the cracks belongs to tension-shearing failure model. A new approach is presented in this paper for combined-type crack propagation and corresponding failure mode.