Study On Crack Propagation Laws And Failure Mechanism Of Rock Mass Induced By Mining

Propagation process and distribution regularities of cracks induced by mining are complex because of initial cracks existence in rock mass. Rock mass failure characteristics during mining are decided to a large extent by initial cracks. Therefore, laws of crack propagation in the overlying strata induced by mining will reveal the mechanism of rock failure and promote the development of rock mechanics.Crack propagation process of fractured rock and overlying strata including initial damage are analyzed detailed based on theoretical research, test study and numerical simulation in this paper.Firstly, mechanical properties are studied by quantitative analysis or qualitative analysis according to the difference of initial damage and the difference of crack spacing on base of the rock mechanics test systems. The curve of damage evolution rate and strain is gained base on damage mechanics.Secondly, Rock damage process of self-organization is studied. Elastic limit is discussed by linear stability analysis. The breakage process of rock beams is analyzed based on synergetic. The influences of loading, mining width, elastic modulus etc on rock beams stability are obtained when the rock beams bending is symmetrical.Thirdly, the influences of crack length, crack quantity and crack spacing without bias double crack on crack propagation under the specific stress states are studied. The crack propagation process is divided into five stages according to fractal dimension - stress curve. Fractal characteristics of crack evolution in different stages are analyzed. The influences of the initial crack geometry elements on the crack fractal dimension were revealed.Finally, crack propagation process in the overlying strata with initial crack is studied. Characteristics of Crack fractal dimention are analyzed with mining width and initial damage. Fractal laws of crack evolution in the overlying strata are obtained.