Relevance between abutment pressure and fractal dimension of crack network induced by mining

Abstract

Based on the geological conditions of coal mining face No. 15-14120 at No. 8 mine of Pingdingshan coal mining group, the real-time evolution of coal-roof crack network with working face advancing was collected with the help of intrinsically safe borehole video instrument. And according to the geology of this working face, a discrete element model was calculated by UDEC. Combining in situ experimental data with numerical results, the relationship between the fractal dimension of boreholes’ wall and the distribution of advanced abutment pressure was studied under the condition of mining advance. The results show that the variation tendency of fractal dimension and the abutment pressure has the same characteristic value. The distance between working face and the peak value of the abutment pressure has a slight increasing trend with the advancing of mining-face. When the working face is set as the original point, the trend of fractal dimension from the far place to the origin can be divided into three phases: constant, steady increasing and constant. And the turning points of these phases are the max-influencing distance (50m) and peak value (15m) of abutment pressure.