Energy accumulation law of surrounding rock in coal thickness variation area and the influence of mining direction on it

To reveal the energy accumulation law of surrounding rock in coal thickness change area and the influence of mining direction on it, this study takes the 17# coal seam of Hegang Junde Coal Mine as the research background, and takes the combined rock strata as the object to discuss the stress transfer mechanism of coal thickness change area. The relationship between the original rock stress and the thickness ratio and elastic modulus ratio of coal rock in the coal thickness change area is revealed, and the influence of mining direction on the mining stress and energy accumulation law in the coal thickness change area is clarified. The following conclusions are obtained: due to the difference in strength (stiffness) between rock and coal, the principal stress distribution in the coal thickness change area is uneven. The peak stress appears in the coal thickness thinning area, and the valley stress appears in the thickening area. The larger the range of coal thickness change and the smaller the elastic modulus ratio of coal and rock, the greater the peak stress and the smaller the valley stress. Under the influence of mining stress, the advance abutment pressure and the abnormal stress of coal thickness change are superimposed in the area of coal thickness change, and the stress concentration of surrounding rock is high. From thin to thick mining, there is an impact danger zone due to the superposition of the advance abutment pressure zone and the stress anomaly zone in front of the working face, and there are two impact danger zones from thick to thin mining, so it is more reasonable to mine from thin to thick. In view of the mining stress and energy accumulation law in the coal thickness change area, the prevention and control ideas of regulating the surrounding rock structure, surrounding rock stress, and increasing impact resistance energy are put forward, the engineering application is carried out, and the application effect is good.