The Influence of Hydraulic Fracturing Fissures on Coal Seam Mining Face Stress

Taking one mining face in Sihe Coal Mine No.3 coal seam of Jincheng Mining Area of Shanxi province as an example, simulation works are done by finite element method based on the observation of the hydraulic fracturing underground to research the effect of hydraulic fracturing and mining safety. Results indicate that local stress release and local stress concentration places are presented at the extension end of hydraulic fracturing. The width of hydraulic fracturing produced in the coal and the properties of proppant under the original stress have some relations with the distribution of mining stress. Namely, the distribution of mining stress is different with the mining without hydraulic fracturing and presents bimodal pattern variation as the distance of the coal wall increasing. The peak value of mining stress is obviously backward transferred. As the material difference coefficient k of coal and proppant is increasing,the maximum and minium horizontal principal stresses flows exponential function.Generally, increasing of fracturing width and the coefficient k is well for releasing stress in the coal reservoir.