Study On Development Characteristics Of Water Flowing Fracture Zone In 4104 Working Face Of Wenjiapo Coal Mine

The water diversion fracture zone is one of the main water diversion channels of mine water gushing(inrush),and its development height is of great significance to the mine water prevention and control work.The sandstone aquifer of Luohe formation in Binchang mining area of Shaanxi Province is one of the main threats to mine safety mining,so it is particularly important to determine the height of water diversion fracture zone and judge the risk of water inrush in Luohe formation sandstone.In this paper,taking 4104 fully mechanized top coal caving face in Wenjiapo Coal Mine as the research object,the development height of water ersion fracture zone in fully mechanized top coal caving face is studied by using FLAC3D finite element numerical simulation and mine-ground combined microseismic monitoring technology.The research results have important reference value for other coal prevention and water control work in Wenjiapo Coal Mine and Binchang Mining area.The FLAC3D numerical simulation results show that in the process of coal seam mining,the stress concentration area is formed in the surrounding rock of the working face,and the the peak value increases continuously with the mining of the working face,and the roof of the goaf forms the tensile stress zone,which shows an increase-decrease-increase rule in the mining process of the working face.The compression-shear failure zone is formed in the surrounding rock of the working face and the high strata above the goaf,and the tensile failure zone is formed in the middle and low strata of the goaf.In the whole process of simulated excavation,the development of water diversion fracture zone is roughly divided into three stages:growth,slow increase and stability.when the mining face is 260m,the water diversion fracture zone develops to the height of 175m above the roof of coal seam.The height of the water conducting fracture zone of 4104 working face is measured by using the well-ground combined microseismic monitoring technology,and a microseismic monitoring network suitable for the study area is designed according to the field monitoring conditions,and the accuracy of the microseismic monitoring network is verified by the method of system calibration.Through the analysis of the number and energy spatial distribution characteristics of microseismic events occurred in the working face before and after passing through fault F21 and under normal mining conditions,it is concluded that under the normal mining condition,the failure of rock strata in the range of 385?470m is mainly caving,and that in the range of 470?600m is mainly fissures,and under the influence of F21 normal fault,the height of caving zone is increased by 20m.The analysis results of the strike,tendency and plane density of microseismic events with different mining footage show that the failure of overlying rock is greatly affected by faults and goaf,and the maximum leading distance of roof rupture increases by 85%.The maximum extension distance between the east and west sides of the working face increased by 31%and 26%respectively.The failure degree of the overlying rock on one side of the goaf is more severe than that on the side without goaf.The results of comprehensive analysis of microseismic monitoring and numerical simulation show that under the condition of no fault influence,the water-conducting fracture zone develops to the middle of the Anding formation,the maximum development height is 171m,and the fracture-production ratio is 24.43.Under the influence of F21 fault,the maximum development height of water diversion fracture zone is 202m,and the fracture-mining ratio is 28.86.