Study On Succession Mechanism Of Ground Water Flow Field And Self-Healing Of Aquifer In Coal Mining In Western China

As a large coal production base in China,the occurrence of coal resources in the western mining area is characterized by shallow burial,thin bedrock and thick surface loose layer.In the process of high strength mining of coal seam working face,coal resources are mined in large quantities,and the overlying strata are broken and unstable to form mining fractures.The fractures develop upward to the groundwater aquifer and even penetrate the surface,which not only causes the collapse and settlement of the surface covered layer,but also causes the large-scale and substantial decline of groundwater after mining fractures penetrate the aquifer,resulting in soil erosion,surface vegetation degradation,groundwater pollution and other ecological and environmental disasters,but also causes the water pressure frame accident of the working face.Threat underground safety and green production.Based on the engineering background of Buertai Coal Mine,this thesis adopts the research methods of field investigation,numerical simulation,physical similarity simulation and theoretical analysis,and takes the working face of 2–2 coal seam in Buertai Coal Mine as the geological prototype to establish a three-dimensional geological calculation model.The three-field evolution law of mining-induced stress field–displacement field–seepage field,the law of groundwater succession,the breaking and instability characteristics of weathered rock and the distribution and evolution law of mining-induced fractures,and the seepage characteristics and distribution and evolution law of water flowing fractures after coal mining are studied.The evaluation method of aquifer self-repair function is proposed.On the basis of fracture self-repair,the industrial intervention repair technology guiding aquifer repair is carried out.Firstly,the groundwater system and aquifer in the western mining area are divided.Based on the topographic and geomorphic characteristics of the typical mining face in the western mining area,the occurrence characteristics of coal and rock,hydrogeological conditions and production technology conditions,the characteristics of the roof aquifer in the working face are analyzed,and the main aquifer and the main water filling aquifer in the working face are divided.Secondly,a method of modeling complex three-dimensional geological body based on drilling data is proposed,and the numerical calculation model of22108 working face is established.Based on FLAC^3D numerical simulation software,numerical calculation was established to study the three-field distribution evolution law of stress field-displacement field-seepage field and the distribution law of mining-induced plastic zone after coal seam mining,and the succession mechanism of groundwater flow field was analyzed.Based on the physical similarity simulation experiment of solid-liquid coupling,the characteristics of rock breaking instability and aquifer failure under fully mining conditions are studied,and the evolution law of fracture distribution and aquifer failure mechanism are analyzed.Thirdly,the similar simulation model of 30 days after mining is used to carry out the water-filled seepage experiment of aquifer,and the seepage law of water-conducting fissures and the change law of water content of overlying rock after mining and after mining stop for a period of time are analyzed and compared to evaluate the self-healing function of aquifer.Finally,the evaluation method of aquifer self-repair function is proposed,and the artificial intervention repair technology based on the characteristics of fracture self-repair guiding aquifer repair is carried out.The research results of this thesis have certain theoretical reference significance and field application value for safe and green mining in western ecological fragile mining area.