Study on development height of water flowing fractured zone in shallow thick coal seam mining of Daheng Coal Mine

Abstract The height of water flowing fractured zone is a key parameter to implement water-retaining mining technology. In order to study the development height of water flowing fractured zone in shallow thick coal seam mining in ecologically fragile areas of western China, taking 91105 working face of Daheng Coal Mine as the research object, the height of water flowing fractured zone is comprehensively determined by empirical formula, rock tensile rate formula, field test and numerical simulation. The results show that the formula calculation and numerical simulation both are close to the measured results, the upward slant hole observing method is reliable for the height observation of water flowing fractured zone. The maximum height of water flowing fractured zone is 53.62 m, the fracture production ratio is 12.32, and the development form is ' saddle '. Compared with the empirical formula, the calculation results of rock tensile rate formula are closer to the measured results, which improves the prediction accuracy of water flowing fractured zone height. It shows the feasibility of water flowing fractured zone height calculation based on rock tensile rate, and provides a new idea for water flowing fractured zone height prediction. Based on the geological conditions of 91105 working face, the numerical simulation analysis shows that the development of water flowing fractured zone undergoes three stages of slow increase, sudden increase and stability. The research results can provide guidance for the implementation of water-preserved coal mining and ecological environment protection in thick coal seams in ecologically fragile areas in the west.