Research On The Development Law Of Water Flowing Fractured Zone During Mining Process Of Inclined Coal Seam In A Coal Mine In Heilongjiang Province

After the coal seam was mined,the stress balance of the surrounding rock is destroyed,and cracks occur in the rock mass under the action of stress,which makes the water in the aquifer above the working face flow into the working face through the water flowing fractured zone,and it is easy to cause the mine water disaster.In order to reveal the development law of water flowing fractured zone under the joint influence of fault and coal seam dip angle,this paper takes a coal mine in Heilongjiang Province as the research object and comprehensively analyzes the development law of coal seam water flowing fractured zone after mining by field exploration,drilling flushing fluid consumption method,underground TV observation method and numerical simulation.The coal-bearing strata in the study area are the Cretaceous Shihezi Formation with an average dip angle of about 30° and well-developed faults.The direct water source of the working face is the lower Cretaceous Shitouhezi Formation aquifer.Based on the analysis of laboratory mechanical test results,the lithology of overburden is divided into medium hard and hard.According to the principles of lead water fracture zones observation hole arrangement,decorate in the study area 1,2 two conductivity fractured belt observation hole,the hole flushing fluid loss,water level observation,downhole television means such as observation of water fractured zone height measured on site,there are 17 # coal seam in the second level of the south three water flowing fractured zone height of 190.35 m,The height of water flowing fractured zone in the goaf of No.17 coal seam in the middle of the study area is 186 m.Taking the 9# coal seam and the 17# coal seam goaf in the middle of the study area as the numerical simulation research object,the three-dimensional engineering geological model cut by the fault was established through the built-in modeling function of FLAC3 D,and the stress and strain field of the overburden and the development law of the mining-induced fracture in the overburden were further studied respectively in the mining process of the 9# and 17# coal under the influence of the fault.The research results show that the water flowing fractured zone develops upward to the loose layer with the advance of the working face during the mining process of No.9 coal.No.17 coal seam is located under the fault zone.Due to the influence of fault fracture zone and coal seam occurrence,mining-induced fracture zone gradually communicated with fault tensile fracture during the mining process,resulting in its spatial distribution as "asymmetric inverted triangle" rather than the traditional "saddle shape".In the vertical direction,the development height of the water flowing fractured zone is bounded by the fault fracture zone.In the horizontal direction,the water flowing fractured zone extends along the fault plane,resulting in a significant increase in the catchment area.By comparing the stress-strain field with the plastic failure zone in the process of mining,the "activation" process of the fault under the influence of mining is confirmed.Finally,by comparing the simulation results with the measured results,it is found that the height of the plastic zone at the No.2 hole in the numerical simulation is basically the same as the measured height of the No.2 hole in the water flowing fractured zone,which is well verified between the two.The research results provide a theoretical basis for the safe mining of inclined coal seam under the influence of fault.