Multi-scale failure mechanics of rock in mining engineering

In mining engineering, the multi-scale failure behavior of surrounding rock under the complex stress environment is a fundamental influencing factor of disasters. This paper systematically summarizes our recent ten years' research progress of rock multi-scale failure mechanics, including macro/meso rock failure mechanics, roadway surrounding rock control and rock strata movement. In terms of laboratory research scale of rock mechanics, the propagation process of rock meso-crack under the thermal-mechanical coupling effect was studied by using the SEM test system, which reveals the meso-fracture mechanism of rock. The macro failure and mechanical properties of rock, coal and coal-rock combined body were experimentally investigated under different loading and unloading conditions. A non-linear model of coal and rock mass macro failure was established. In terms of roadway failure scale, the stress gradient failure mechanism of the surrounding rock of roadway was revealed, the theory of uniform strength support in deep roadway was established, which guides the direction of roadway support. Then the full-space collaborative control technology of roadway was proposed and applied on site. In terms of rock fracture mechanics and movement scale, the evolution of roof fracture modes of different thicknesses was studied by experiments, and four roof fracture modes and fracture mode partitions were obtained. Based on the theory of key strata, the analogous hyperbola model and the inner and outer analogous hyperbola model of overburden movement caused by mining were proposed. The evolution of the analogous hyperbola model with the variation of the key layer position and the dip angle of coal seam was analyzed. The above results will provide theoretical and technical support for the prevention and control of coal mining disasters in our country.