MECHANISM OF COMPLEX MINE PRESSURE MANIFESTATION ON COAL MINING WORK FACES AND ANALYSIS ON THE INSTABILITY CONDITION OF ROOF BLOCKS

摘要

Irregular weighing of work faces affects normal mining of the coal seam. With respect to the features of complex mine pressure manifestation on work faces, modeling analysis was conducted on the motion instability of fractured blocks of overlying strata based on existing research. Method of probability analysis was employed to reveal the mechanism of complex mine pressure manifestation and obtain the instability conditions of fractured roof blocks. The research indicates that the rule of movement instability of fractured roof blocks obeys an exponential failure probability density function; in the context of probability description of roof block instability, the instability condition of fractured blocks is a nonhomogeneous partial differential equation; when an integer multiple of the fracture block size is used as the instability parameter of roof, the instability condition of roof depends on block size, number of fractured blocks and roof instability coefficient, and this instability parameter was utilized to explain the mechanism of irregular weighting of work faces; the weighting distance of work faces was analyzed and predicted with considerations of actual conditions of coal seam; the number of fractured blocks and the structural features of roof under the disturbance of mining on work faces were obtained by inverting the measured mine pressure data, which provides a new method to predict and forecast the manifestation of mine pressure on work faces under complex conditions of weighting.