卸荷条件下裂隙岩体变形破坏及裂纹扩展演化的物理模型试验

 岩体工程开挖是一个卸荷过程，通过裂隙岩体物理模型试验，研究2种卸荷应力路径下裂隙岩体的强度、变形及破坏特征，并探讨裂隙的扩展演化过程和力学机制。卸荷条件下裂隙岩体的强度、变形破坏及裂隙扩展均受裂隙与卸荷方向夹角及裂隙间的组合关系影响；卸荷速率及初始应力场大小主要影响岩体卸荷强度及次生裂缝的数量，对裂隙扩展方式影响相对较少；卸荷条件下裂隙扩展是在卸荷差异回弹变形引起的拉应力和裂隙面剪切力增大而抗剪力减小的综合作用下的破坏，且各个应力对裂隙扩展的影响大小与裂隙的倾角密切相关。

PHYSICAL MODEL TEST ON DEFORMATION FAILURE AND CRACK PROPAGATION EVOLVEMENT OF FISSURED ROCKS UNDER UNLOADING

The excavation in rocks is mainly an unloading behavior. The characteristics of strength and deformation failure of rocks are researched;propagation evolvement and mechanical mechanism of cracks are discussed under two unloading stress paths based on physical model test of fissured rocks. The strength and deformation failure of rocks,propagation of cracks are obviously impacted by the included angle of cracks with unloading direction and combination between cracks. The magnitude of unloading velocity and initial stress mainly influence strength and amount of sub-cracks on fissured rocks,but little on the law of expanding mode and deformation. The propagation of cracks is made by tensile stress brought via different rebound deformations and shear stress increasing but resisting shear decreasing under unloading;and the influence of these stresses on the expanding evolvement is highly related with dip angle of cracks.