岩石张拉及剪切破裂声发射震源机制分析

选取花岗岩,开展三点弯曲和剪切加载条件下声发射试验,采用单纯形算法与矩张量理论分析了不同破裂类型微裂纹的时空分布特征.研究结果表明:在加载过程中,三点弯曲试样总体上以张拉型破裂为主,岩石最终破坏时,张拉型裂纹所占比例超过50%;剪切试样以剪切型破裂为主,最终剪切型裂纹所占比例超过60%.声发射事件的群集区域和矩张量分析结果与最终的岩石破裂结果相一致,说明矩张量理论能够定量描述岩石在加载过程中张拉应力、剪切应力的分布和迁移规律,这为岩石破裂过程中微裂纹的相互作用和贯通机制提供了良好的分析手段.

Analysis of Acoustic Emission Source Mechanisms for Tensile and Shear Cracks of Rock Fractures

Acoustic emission (AE) technique was employed to measure the AE signals of granite for three-point bending tests and shear tests. The spatial-temporal distributions of various fractures micro-cracks were studied based on the simplex locating algorithm and moment tensor theory. The results showed that the micro-cracks generated from the three-point bending tests are mainly of tensile type， accounting for more than 50% of the total events. For the shear tests， the micro-cracks of shear type are prominent whose proportion is more than 60% with rock failure. Moreover， the results of the distribution of AE locations and moment tensors are in agreement with the macroscopic fractures at the end of the experiments， which can be used to describe the distribution and migration of tensile and shear stress when rocks are under loading. The results indicated that the moment tensor theory is a very useful method for studying AE source mechanisms and spatial-temporal vibrations of micro-cracks.