Temporal and spatial evolution characteristics of stress in overlying strata of complex mining in mixed residual area

In this paper, the characteristics of overburden stress evolution caused by oblique crossing of compound mining face over mixed residual mining area are systematically studied by using the methods of three-dimensional similarity simulation and numerical simulation.Firstly, in the process of oblique crossing of compound mining face over room residual mining area, the stress value of roof in front of working face increases rapidly before and after the direct roof span falling.Under the disturbance load, the edge of coal pillar will be fractured, and reasonable support distance and roof control distance should be selected in the process of re-mining of room residual mining area.Then, when the same mining method passes through the roadway-type residual mining area, the roof of 0-5 m stratum in the upper part of the stope has obvious stress support effect on the overburden.Finally, whether through the room-type or roadway-type residual mining area, the scheme of oblique crossing over the residual mining area of the duplicate mining face is reasonable and feasible.