Abstract:
In order to explore the evolution characteristics of cracks and strain energy during the progressive failure process of coal and rock mass around the gas drainage borehole, in this paper, complete samples and samples with holes are designed to carry out progressive failure tests. Through the VIC-3D observation system, we obtain the surface deformation of the sample, calculate and analyze the dynamic evolution process of the surface cracks, the distribution of the cracks and the evolution characteristics of strain energy, and obtain the following conclusion: the compressive strength of the sample with the hole is low, and there are many cracks around the drill hole, and the upper and lower sides of the hole are deformed seriously. It shows that: in the actual drilling process, the compressive strength of coal and rock mass will be greatly reduced, and many cracks will be generated around the drilling, which will cause the drilling damage and even the collapse of the hole. During the progressive failure process, the surface cracks of the coal and rock mass around the hole undergo dynamic evolution, and the dynamic evolution process corresponds to the loading stress. At the same time, by comparing the evolution characteristics of the crack opening and the dislocation amount, the main type of cracks for the sample failure can be determined. It is an open and staggered mixed type of fissure. During the progressive failure process, the evolution process of the surface cracks of the coal and rock mass around the hole maintains a corresponding relationship with the accumulation of deformation energy density in the localized area. The strain energy density evolution characteristics of different localized regions are different, which reflects the coal and rock mass around the hole. There is internal energy adjustment in the progressive destruction process.