论文部分内容阅读
岩石在荷载作用下产生宏观破坏,其断裂面的细观形态变化,可以间接地反映岩石内部损伤演化进程,并与其宏观力学状态和结构破坏特性之间存在必然联系。主要对巴西劈裂试验和剪切试验试样的断裂面进行电镜扫描,总结典型力学特征下试样断裂面的细观形貌特征,建立裂纹断裂面细观形貌与宏观力学特性匹配的判断标准。进而对含不同倾角预制单裂纹试样单轴压缩试样的破坏全断面进行细观扫描分析,采用判断标准对其细观形貌判别,得到断裂面的拉剪应力分布权重,探究断裂面拉、剪应力分布随裂纹扩展过程的变化规律。试验结果表明:全断面拉剪应力权重与预制裂纹倾角有密切关系。预制裂纹倾角小于45°时,断裂面以拉应力为主,且随着裂纹扩展拉应力权重逐渐减小,剪应力权重逐渐增大;当裂纹倾角大于45°时,其结论与前述结论相反;预制裂纹倾角为45°时,拉、剪应力共同作用产生翼裂纹及次生裂纹2种扩展方式,翼裂纹扩展由拉应力主导向剪切应力主导过渡,次生裂纹扩展过程中主导应力变化规律与之相反。
The macroscopic failure of the rock under the action of load and the change of the mesoscopic morphology of the fracture surface can indirectly reflect the evolution of the damage in the rock and have a necessary relationship with the macroscopic mechanical properties and structural failure characteristics. The rupture surface of the Brazilian splitting test and the shear test specimen were mainly scanned by electron microscope. The microscopic topography characteristics of the fracture surface of the specimen under typical mechanical characteristics were summarized, and the judgment of the matching of the microscopic morphology and macroscopic mechanical properties of the fracture surface was established standard. Then, the whole section of uniaxial compression specimens with different prefabricated pre-cracked single-crack specimens was analyzed by microscopic scanning. The judgment standard was used to judge the mesoscopic morphology, and the tensile shear stress distribution weight of the fracture surface was obtained. , The distribution of shear stress changes with the crack propagation process. The test results show that: the whole section of tensile shear stress and precast cracks have a close relationship. When the inclination of prefabricated crack is less than 45 °, the tensile stress is the main fracture surface, and the tensile stress decreases gradually as the crack propagates. The weight of shear stress increases gradually. When the dip angle of crack is more than 45 °, the conclusion is contrary to the above conclusion. When the prefabricated crack angle is 45 °, the two modes of wing crack and secondary crack are produced by the combination of tensile and shear stresses. The wing crack propagation is dominated by the transition from tensile stress to shear stress, and the dominant stress changes in secondary crack propagation to the opposite.