中文摘要：

根据Ⅰ型裂缝和Ⅱ型裂缝在损伤与断裂耦合方面的联系，基于Ⅰ型裂缝的损伤方程推导出更适用于Ⅱ型裂缝的损伤演化方程，得到损伤区Ⅱ的计算方法。通过损伤梯度研究Ⅱ型裂缝从损伤至开裂阶段裂缝发展方向的变化规律，最终得到Ⅱ型裂缝的扩展角是79°。将该扩展角与经典判据得到的扩展角进行对比，结果表明该方法是可行的。

英文摘要：

According to research on modeⅠand modeⅡcrack damage coupled with fractures, a damage evolution equation that is more suitable for mode Ⅱ cracks was established based on the damage equation of a mode Ⅰcrack. Then, the calculation method for the damage area was obtained. The variation of the direction in which the crack developed was studied using the damage gradient, over a period ranging from damage to cracking of the modeⅡ crack. Finally, the propagation angle of the mode Ⅱ crack was determined to be 79°. This propagation angle was compared with that obtained by the classic criterion. The results show that the method used in this study is feasible.