Development and Evolution Law of Surface Mining Fractures in Shallow Thick Coal Seam Mining
Based on the occurrence of overlying rock and the development characteristics of surface mining-induced fractures in typical working face of Chuancao Gedan coal mine,the instability movement of key strata of overlying rock and its influence on the development of surface mining-induced fractures,as well as the influence of base-mining ratio on the evolution law of surface mining-induced fractures are studied by field measurement,theoretical analysis and numerical calculation.The results show that the development type of surface mining fractures is controlled by the instability movement of key layer in the mining process of shallow and thick coal seam.The slide and instability of key layer cause the surface to produce step type fractures,and the key layer turn and instability cause the surface to produce open type fractures.With the increase of the basic-mining ratio,the vertical dislocation momentum of surface mining fractures decreases,while the horizontal opening quantity increases.The horizontal crack opening is linearly related to the key layer rotation angle.
shallow thick coal seamkey stratumsurface mining fracturedevelopment and evolution law
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