To investigate the fractal characteristics of the fracture network in overlying strata mining under different breaking distances in Shendong mining area,this study summarized and analyzed the influencing factors of basic roof periodic breaking distance.The 52505 working face of Daliuta coal mine and the 12401 working face of Shangwan coal mine were selected for physical similarity simulation experiments and the distribution characteristics of the overburden fracture network under different breaking distances were explored.With the help of Matlab,the fractal dimension values of different overburden fracture network distributions were obtained and the development characteristics of overburden fracture were quantitatively described.The settlement law of different strata under the influence of overburden fracture propagation was further discussed.The results show that the main factors affecting the periodic fracture distance of the main roof include the thickness,the tensile strength,and the bearing load of the main roof.The average breaking distances of simulated mining in Daliuta 52505 working face and Shangwan 12401 working face are 20 and 30.4 m respectively.The fractal dimension of the overburden fracture network under different breaking distances shows a stepwise growth trend with the advancement of the coal seam working face,and the fractal dimension can better characterize the distribution of overburden fractures.The variation trend of the highest separation fracture development height and fractal dimension of the two working faces is an approximately nonlinear positive correlation.Different breaking distances have a significant impact on the development and expansion trend of the overall fracture of the overlying strata.The fractal dimension value of Daliuta 52505 working face is relatively low in the early stage of working face mining,but it is opposite in the middle and late stages of mining.The fracture distance is small,and the overall fracture development degree of the overlying rock is relatively higher.The subsidence curve of the overlying strata of the two working faces is"convex",which is approximately symmetrical to the middle of the goaf.
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