岩石剪切破坏裂纹演化特征量化分析

 为深入研究岩石破坏过程表面裂纹演化规律，探讨表面裂纹与内部破裂之间的内在联系，对砂岩剪切过程中表面裂纹演化特征进行量化，分析砂岩剪切破坏表面裂纹演化模式，建立表面裂纹量化参数与应力状态和声发射特征之间的关系，并探讨含水状态对岩石剪切破坏表面裂纹量化参数的影响。研究结果表明：砂岩在剪切过程中伴随着表面雁行裂纹的形成与贯通，雁行裂纹宏观形态出现于破坏前的极短时间内，随后岩石发生剪切贯通；最大AE事件率总是出现在剪应力急剧下降来临之前极短时间内，且出现在表面裂纹非稳定快速扩展之前；饱水系数影响了表面裂纹出现的时间和相对于峰值剪应力的位置，随着饱水系数的增加，砂岩表面裂纹出现时间变早，最大瞬时贯通速度呈依次递减规律，贯通时间变长，表面裂纹快速扩展滞后时间呈明显增加趋势。

QUANTITATIVE ANALYSIS ON DEVELOPMENT OF SURFACE CRACKS OF ROCKS UPON SHEAR FAILURE

In order to investigate the development of surface cracks and the intrinsic link between the surface cracks and the internal rupture in the process of rock failure，the developmental characteristics of surface cracks of rock during shear failure were quantitatively analyzed and relationships among the parameters describing the surface cracks，the stress state and the acoustic emission characteristics were established. Meanwhile，effects of water content on the parameters describing surface cracks upon shear failure were investigated. The results revealed that the echelon cracks accompanied with the formation and transfixion of surface cracks during shearing process and appeared for a very short period just before rock failure，then shear cracks penetrated through completely. The maximum rate of AE event appeared always for a very short period before the sharp drop of shear stress，and before the occurrence of the non-stable state of rapid propagation of surface cracks. The coefficient of saturation was found to affect the time and the position of occurrence of surface cracks relative to the peak shear stress. As the coefficient of saturation increased，the surface cracks occurred earlier，the maximum instantaneous transfixion velocity decreased，the transfixion time was longer and the time delay of the rapid propagation of surface cracks increased significantly.