| Water inrush from unconsolidated aquifer is an important type of mine water inrush,which affects safe and effective mining.In the shallow coal seam,water inrush is easy to occur once the roof water-conducting fracture zone communicates with the loose strong aquifer in the mining process.The thickness of the Cenozoic loose layer in the north second mining area of guqiao mine is 323.50~524.76m.Due to its large thickness,the water-rich aquifer is strong,and the loose aquifer in some areas is in direct contact with the bedrock.If water inrush occurs between the water-conducting fracture zone and the unconsolidated aquifer during mining,it will threaten the safety of the mine.Therefore,it is necessary to study the development characteristics of overburden failure and water-conducting fracture zone in coal seam mining in the north no.2 mining area of guqiao coal mine,so as to provide technical support for the prevention and control of water damage of loose aquifer.In collecting north second mining area of guqiao coal mine exploration phase and production phase,filling can be phase data,and adjacent to mine data,on the basis of using mathematical statistics,data analysis and theoretical calculation,numerical simulation,similar simulation experiment of combining the method of straight strong north two mining thick loose aquifer of guqiao coal mine coal seam mining under overlying strata failure characteristics of comprehensive study,the following results.(1)North two mining thickness of Cenozoic group,on the whole,from southeast to northwest gradually thickening,along with the change of the ancient morphology change,on the Cenozoic contains,including with the basic no hydraulic connection between,had no direct effect on the mine water filling,the bottom of the mining area have separated water is extremely good water-resisting layer,only in the eastern mining area of water-resisting layer is very weak,including and lower part of the region,direct contact with the bedrock water contact.(2)In the second coal mining area of north China,the roof of 11-2 coal seam is mainly of the old roof type,the pseudo roof type and the pseudo roof type.The lithology of the roof rock and the overlying rock is mainly of soft rock~medium hard rock.According to the rock physical and mechanical parameters and geological and hydrogeological data,the hydro-engineering geological model of coal seam mining under the thick unconsolidated aquifer is established.(3)According to the leakage analysis of water injection drilling and washing fluid,the height of caving zone is 18.4m,and the height of water-conducting fracture zone is 48.14m.The height of water-conducting fracture zone and caving zone in overburden rock are respectively 40.0m and 18.0m by distributed optical fiber and high-density electrical method.(4)According to the《code for coal pillar setting and pressure coal mining in buildings,water bodies,railways and main roadways》(2017.05)the height of water-conducting fracture zone in coal seam mining in the second mining area of north China is calculated as 36m~47.98mm,and 34m~53.54m for formula 2.The height of water-conducting fracture zone is calculated as 46m~48.94m according to the《code for hydrogeological engineering geological exploration in the mining area》(GB12719—1991).The empirical formula of huainan mining area calculates that the water-conducting fracture zone of 11-2 coal seam is highly concentrated at34.23~47.89m,which is 11.4~16 times of the mining height.The height of the water-conducting fracture zone was calculated by using the multiple regression mathematical model to be 36.01m~47.74m,with an average of 42.20m.(5)FLAC~3DD software was used to simulate and analyze the failure characteristics of overlying strata in coal mining directly under thick unconsolidated aquifer.The research results were as follows:the height of caving zone was 24.5m,and the height of water-conducting fracture zone was 42.5m.Through the similar simulation test,it is found that the roof of coal seam caved down for the first time at the mining height of 45m,and the caving zone reaches the highest and tends to be stable at the mining height of 135m.With the advance of coal seam mining,the overlying strata failure presents certain regularity.The final simulation results:the height of caving zone is 27.5m,and the height of water-conducting fracture zone is43m.Figure[54]Table[14]Parameter[56]... |
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