Research on Stress Distribution and Failure Depth of Mining Floor During the First Weighting of Main Roof

In order to research on stress distribution and failure depth of mining floor during the first weighting of main roof, based on the analysis of abutment pressure distribution in this case, an elastic mechanics model is established to calculate the stress of any point in the floor, expressions for this model are deduced, and meanwhile a failure criterion of floor rock is put forward according to the Mohr-Coulomb failure criteria. Take the parameters of 3612 mining face of Zhu Zhuang coal mine as an example, through solving stress distribution of mining floor during its first weighting of main roof, stress contour and failure district of floor are given out. The result shows that, the failure depth of 3612 mining floor is 12.4m, which is rather close to the measured value 13m, thus the utility and reliability of this study method is well verified. The result provides theoretical basis for bottom grouting strengthening before the first weighting of main roof, and establishes the theoretical foundation for further research on safe mining on confined waters.