Study On Ecological Restoration Of Overlying Goaf Area In Coal Mine

At present,coal is still the main disposable energy source in China at this stage.In the past few decades,under the background of the country’s vigorous economic development,the uncontrolled and unreasonable development of some coal mine resources cities and regions has led to a serious breakdown of the ecological environment in mining areas.Among them,the artificial chambers left over from coal mining have caused potential threats and damage to their overlying areas,causing ecological and environmental damage and many potential safety hazards,affecting the normal production and life of residents of coal cities and coal mining areas,destroying the appearance of cities and wasting land resources.Therefore,it is very necessary to study the ecological restoration of the overlying area of coal mine goaf.This paper takes Hemei No.8 mine as the research object,this paper uses on-site exploration,numerical simulation and other methods to carry out a feasibility study of ecological restoration projects in the overlying area of the goaf,aiming to solve the problems of land resource utilization and ecological destruction in the coal mine goaf.The research content mainly includes two parts:ecological restoration engineering scheme design and numerical simulation.Through the research,the following conclusions are obtained:（1）Through the actual investigation and data collection of Hemei No.8 mine,the ecological status and existing major problems of the mining area are clarified,and the wetland ecological restoration project scheme of Hemei No.8 mine is designed based on the layout of ecological restoration project of mountains,rivers,forests,fields,lakes and grass in south Taihang area of Shancheng District,Hebi City.Solutions including surface to reshape（including dangerous house demolition project,trash pickup,sunken pit backfill engineering）and ground fissures,wetlands and river management scheme（including ecological filter dam construction project,the observation deck construction,ecological construction engineering computation,river land greening projects）,the land reclamation plan（farmland shelterbelt construction engineering,road construction projects,land of farmland stripping flat again The whole project,soil fertility restoration measures）3 sub-programs,targeted to solve a series of problems brought by coal mining.（2）Using FLAC3D combined with Rhino+griddle and other tools,a large three-dimensional numerical model of the mining area is constructed,and the interaction between the goaf and the restoration project is simulated.The main research results include:1)The stability simulation of the mining area is carried out.The results show that the surface settlement of the mining area is caused by the roof collapse of coal seam under the disturbance of the first level and the second level mining,and the surface settlement value is between 0.1 and 0.4m.The maximum settlement is distributed at the top of the goaf,and the maximum settlement value is 1.86m.2)According to the design of ecological restoration project,100 grade graded load is applied to the core area of the project.By analyzing the relationship between stratum settlement and graded load,it can be seen that when i<10（i is the load series）,that is X₁₀<100k Pa（X_iis the graded load）,there is no obvious settlement on the surface and goaf.When i=10,That is X₁₀=100k Pa,the surface begins to settle,the settlement is0.0092m,at this time,the stratum near the goaf has no settlement.When i>10,that is X₁₀>100k Pa,the settlement basically increases with the increase of load.When i>17,that is X_i>170kPa,the obvious settlement near the goaf begins to appear.When i=17,that is X₁₇=170k Pa,the settlement near the goaf is 0.0012m.When i=100,that is X₁₀₀=1000k Pa,the maximum settlement of the surface is 0.14m,wherein,the maximum settlement of the No.1 surface monitoring point（"ID:119971"）is 0.13m,and the maximum settlement of the No.2 goaf monitoring point（"ID:75209"）is 0.026m.3)According to the design and layout of the ecological restoration project,it can be seen from the analysis of the impact of the load generated by the engineering structure on the goaf and formation.The maximum settlement under the engineering load is distributed at the bottom of the 3#dam,the maximum settlement is 3.2×10^-6m,and the maximum impact radius is 11m.At this time,there is basically no settlement in the upper formation in the goaf.4)Under the engineering load,the influence of the currently mining work on the engineering design of the mined area was simulated.According to the mining technology,the influence of the coal mining face advancing 30m,accumulating 80m,accumulating 180m,accumulating 380m and accumulating 880m on the overburden strata of the goaf and the restoration project was simulated.The results showed that,When and only when the cumulative advance reaches 880m,the maximum influence radius is greater than the buried depth of goaf（three levels）,and the surface settlement occurs at this time,with the settlement between 0.025 and 0.050m.