Failure Characteristics and Stability Analysis of Different Mining Methods for Shallow Buried Coal Seams

Aiming at the problems of surface collapse, soil erosion, ecological damage and others caused by shallow buried soft rock coal seam mining in western China, taking the shallow buried coal seams in Ordos region of Inner Mongolia as the research object. Through a combination method of similarity simulation and numerical simulation, the failure characteristics and stability laws of overburden rock of the collapse method, the strip filling method with the residual large coal pillars, and the full mining and filling method without large coal pillars are systematically studied. Based on the key layer theory, the overburden rock failure modes under different mining methods are revealed. The research results show that the maximum surface subsidence values corresponding to the three types of mining methods are 2850 mm, 1150 mm, and 350 mm, respectively, and the heights of the water conducting fissure zones are 68.5 m, 32.1 m, and 15.8 m, respectively. The secondary rock strata disturbance phenomena in the full mining and full filling method have obvious spatiotemporal characteristics: the interval between the two disturbances is 7-14 d, the displacement increment reaches 15-45 mm, and the stress increment reaches 0.5-1.2 MPa. The research results can provide theoretical reference for coal seam green mining in ecologically fragile areas in the western region.