Similar simulation study on displacement and stress changes response to coal mining in Longdong coal mine, China

The complicated geological conditions, including the Fault Sun, in East No. 2 mining sub-area of Longdong coal mining will influence the stability of the stratum during the mining processes, leading to serious geological hazards. To circumvent this issue, a similar simulation experiment was designed and performed in this study, in which the failure characteristics, evolutions in displacement and stress within stratum were investigated, and the optimum width of waterproof coal pillar determined. The results showed that, as the working face progressed, the coal seam roof gradually deformed, from initial caving of the immediate roof to complete movement and curved subsidence of the entire roof. Significant changes in displacement and stress within the coal seam roof were recorded and increased during continuous mining activity. Displacement and stress difference at two sides of the fault gradually increased and reached remarkable values with an increase in the mining distance. Based on the experiment results, the water inrush is believed to be caused by the interaction between mining and fault, and calculated from parameters collected in field investigations, a 50 m-width waterproof coal pillar should be established to prevent Fault Sun activation thereby reducing the risk of water inrush to neighboring aquifers.