49 / 2023-03-30 17:30:54

Evolution characteristics and mechanical conditions of overlying rock structure in goaf

overburden structure,Stress filed evolution,stable conditions

Based on the assumption of the plane problem of elasticity, the mechanical conditions of overlying rock structure are simplified in the direction of the strike and dip section of the working face, which are solved as the plane stress problem and plane strain problem respectively. Taking the overlying rock of typical mining strata as an example, the evolution characteristics and mechanical property change mechanism of the overlying rock of goaf foundation are studied. The fault movement of different overburden structures is described, and each structure is classified according to whether the main key layer is broken or not. The formation mechanism of positive funnel-shaped, inverted funnel-shaped and hyperboloid overburden structures is explained. The results show that the fracture characteristics of the immediate roof and key beds will affect the ultimate evolution form of the overburden structure. With the development and disappearance of overburden arch, the mechanical conditions of overburden structure directly affect its evolution characteristics. In the overlying rock of the goaf, the main bearing body mainly consists of beam type, arch type and their combination structure. There are differences and relations among the three structures, and with the change of mechanical structure and boundary conditions, the three structures will transform into each other. The numerical model of overlying rock structure in goaf was established by using 3DEC discrete element numerical simulation software, and the stress distribution characteristics of bedrock before and after fracture were obtained. The arch force transfer mechanism of overlying strata stress is discussed and the rationality of the theoretical model of overlying strata mechanical structure is verified.