Study On Water Inrush Law And Catastrophe Model Of Deep Mining Coal Seam Floor In Hanxing Mining Area

With the long-term development of shallow coal resources,recoverable reserves are becoming increasingly scarce,while deep coal resources still have huge development potential and are important strategic reserve resources in China.Therefore,more and more mines have been transferred to the deep coal mining,and the hydrogeological conditions of the coal mining are becoming more and more complicated.Under the combined effect of high geostress and high water pressure,the bottom water-impermeable rock layer is destabilized.The threat of high-pressure water inrush from Ordovician limestone on the floor is increasing.This paper combines the hydrogeological conditions of the Hanxing area with engineering practices in the deep working face of the Xingdong mine,and applies theoretical knowledge and technical methods such as hydrogeology,hydrogeochemistry,elastoplastic mechanics,rock mechanics,numerical simulation,gray theory,and GIS.The water inrush law and the water inrush catastrophic model of the coal seam floor in deep mining have been systematically studied,and a method for evaluating the risk of water inrush in the bottom of thick aquifers under pressure is developed.This article has achieved the following research results:1.Comprehensively summarize the rules of water inrush from the gray floor of the deep working face of 2127,2222,and 2228.The water output has the characteristics of"high energy storage-peak breakthrough-gradual decline".The water quality of Austrian grey water changed from the initial SO₄-Na·K-type water to SO₄-Ca-type water,with K⁺and Na⁺ions as the main phase and Ca²⁺ions as the main phase.This water quality change is due to the strong fragmentation of deep rock masses and the formation of planar fissures,which increases the water permeability of the medium,resulting from the alternating adsorption and mixing of cations.2.Based on the theory of fluid-structure interaction,FLAC^3d numerical simulation experiments are used to study the crack expansion and penetration of coal seam floor under the combined action of mining stress field and confined water pressure change law.?1?According to the data of the stress monitoring points of the bottom plate,the monitoring points?145m from the working surface?in the large limestone show the law of increasing horizontal stress in the x and y directions and decreasing vertical stress in the z direction,indicating that mining in the condition of deep mining The vertical range of the disturbance is very large.The position of 145m below the floor is still within the range of the mining disturbance.The overall three-dimensional stress of the thick aquifer breaks the original balance,increasing the possibility of deformation and damage of the surrounding rock,which is a high pressure Water propagates upward along the cracks to create conditions.?2?The pore water pressure change law and mechanism are as follows:The initial pore water pressure value of the model is10.2MPa.With the excavation of the coal seam,the pore water pressure value slowly increases,reaching a peak of 14.2MPa,and then drops sharply to 9.3MPa,and then increases and decreases.Alternating change phenomenon,and eventually the pore water pressure also tends to be stable with the completion of push mining,which is stable at about 10MPa.The reason is that in the initial stage of coal mining,the advanced support pressure compresses the pores in the aquifer below the floor of the working face,thereby compressing the volume of groundwater in the pore medium and increasing the pore water pressure.When coal seam mining produces fissures in the bottom water-proof rock formation,and the fissures are opened and expanded,the groundwater under compression at this time is guided along the fissures into new fissured spaces,and the instantaneous pore pressure is released,and the pore pressure value is reduced.The subsequent phenomenon of alternating growth and decline is due to the further generation of cracks in the floor and increased permeability.The volume of groundwater in the new fissure space is compressed and stored again,resulting in a gradual increase in pore water pressure,which fluctuates periodically.3.Combined with the thick layer of thin aquifers and thin layers of limestone in the Hanxing mining area,combined with the“high in-situ stress+high water pressure”coupling effect of the deep expansion of the original floor,the original crack propagation mechanism of the complete floor has established a catastrophic catastrophic model of water inrush in the bottom of the deep coal seam..This water inrush mode has five characteristics,which are summarized as the total source of the water-filled water source progressively,the surface dispersion of the water-filled channel,the step increase of the water-filled intensity,the lagging time of the water-filled water,and the exchange of water quality of the water-filled water source Adsorption,that is,the characteristics of water inrush from the deep bottom plate of"transition progress,surface dispersion,step growth,lagging out water,exchange adsorption".4.The main controlling factors of water inrush from coal floor are systematically analyzed.Based on the interval grey optimal clustering theory,with the help of GIS spatial information management and analysis functions,a water inrush from the bottom of thick aquifers under pressure is established.Risk assessment method.The evaluation method is used to evaluate the risk of water inrush from the floor to the 2nd coal seam of Wutongzhuang Mine and the 2nd coal seam of Xingdong Mine.The comparison between the evaluation results and actual engineering results shows that the evaluation method is highly reliable.This research paper consists of 84 figures,24 tables and 79 references.