Study On Evolution Law And Seeppage Characteristics Of Mining-induced Fissure In Overlying Rock Of Shallow And Thick Coal Seam In Loess Gully Region

The occurrence of coal resources of the loess hilly areas with more shallow mining thickness,surface thick loose bed,big and thin bedrock,with the mass production of the coal resources,overburden often appear periodically according to the working face advance of mining fissure,not only surface loess layer cutting property damage,serious erosion,surface vegetation dying soil and water conservation and ecological environmental disasters,It is often connected with the working face and goaf,leading to air leakage and water and sand flooding accidents on the working face,and affecting the safe and green production on the working face.Taking the typical shallow and deep coal seam mining in the loess gully area of the6102 working face of Chuancao Gedan Coal Mine as the research object,this paper adopts a research method combining field investigation,physical similarity simulation,numerical simulation and theoretical analysis.Carried out in the shallow buried thick overburden rock breakage of the loess hilly areas instability characteristics and mining fissure distribution evolution,mining stress and displacement of overburden rock fracture in three evolution and evolutionary regularity of mining fissure,overburden rock mining fissure seepage characteristics and the evolution law and other research,based on the strata mining fissure permeability control to ensure the safety of the green mining technology,It provides some theoretical basis for safe and green mining of shallow and thick coal seam in loess gully area.Firstly,based on the topographic and geomorphic characteristics of the working face,the occurrence characteristics of coal strata and the production technical conditions of the shallow thick coal seam in the typical loess gully region,the typical mining damage caused by mining-induced cracks in the overlying rock of the shallow thick coal seam in the loess gully region and its influence were classified and analyzed.Secondly,using the combination of similarity simulation and numerical calculation,the characteristics of overburden rock instability and fracture,and the distribution evolution law of overburden stress field and displacement field under the initial and repeated mining of shallow and thick coal seam in the loess gully region are studied.Based on the variation law of horizontal and vertical mining-induced fissure opening and dislocation momentum of overlying strata,the development and evolution law of mining-induced fissure development and closure characteristics of overlying strata under the initial and repeated mining of shallow and thick coal seams in loess gully region were analyzed.Thirdly,using the surface rainfall infiltration experiment,the seepage characteristics of the overlying strata mining-induced fractures under the condition of full mining were studied,the formation mechanism and main influencing factors of the seepage channels of the overlying strata mining-induced fractures were analyzed,the classification method of the seepage channels of the overlying strata mining-induced fractures was proposed,and the seepage channels of the overlying strata were classified.Finally,the seepage characteristics of overlying mining-induced fissures are evaluated by zoning,and the safe and green mining guarantee technology based on the permeability control of overlying mining-induced fissures in the loess gully region is proposed.The research results of this paper have certain theoretical reference significance and field application value for safe and green mining of shallow and thick coal seam in loess gully region.