Study On Spatio-Temporal Evolution Of Surface Subsidence And Dynamic Reclamation Opportunity In Deep Coal Seam Mining

Surface subsidence caused by mining is the source of damage to mining habitats,and the prediction and control of surface subsidence has also been highly valued by the state,especially the surface subsidence of deep mining presents a different temporal and spatial evolution law from shallow mining,and is increasingly known as a research hotspot in the field of rock movement control.At present,the research on prediction and control of surface subsidence mostly focuses on shallow mining areas,and there is a lack of research on the influencing factors of maximum surface subsidence velocity under deep mining.And in our country mining area the land reclamation way still stops in the post-processing stage,the rate of reclamation is low,project is difficult,cost is high,the reclamation land quality is poor..Therefore,it is of great practical significance to carry out the simulation of the temporal and spatial evolution law of surface subsidence under deep mining and the research on the timing of dynamic reclamation.This article takes the Hongqinghe Coal Mine in Ordos as an example,first through the establishment of deep mining surface subsidence analysis model under different mining depth,mining thickness,overlaid rock firmness coefficient and advancing speed,based on the orthogonal design factor significance analysis and comprehensive design factor influence analysis,the main influencing factors of the maximum surface subsidence speed under deep mining;Secondly,ABAQUS numerical simulation software was used to establish 501 working face model.Based on the numerical simulation results,the spatio-temporal evolution law of surface subsidence was analyzed.The numerical simulation results were verified by integrating the on-site traditional observation,UAV Lidar monitoring and InSAR monitoring analysis results.Finally,the model of five mining areas was established.Combined with the numerical simulation results and the field advancement,the surface subsidence evolution law was comprehensively analyzed,and the reclamation opportunity and scope were determined.The main conclusions are as follows:(1)The main and secondary factors affecting the maximum surface subsidence velocity under deep mining are mining thickness,advancing speed,overburden firmness coefficient and mining depth from large to small.The depth of mining had the worst effect on the index,indicating that for deep mining beyond 500 m,depth mining was not the dominant factor affecting the subsidence velocity of the land,which was significantly different from the characteristics of shallow mining strongly affected by mining depth.The maximum sinking speed was negatively correlated with the overlying firmness coefficient,and positively correlated with the mining thickness and face propulsion speed.(2)Under deep mining,the surface subsidence gradually decreases from goaf to both sides.With the continuous advance of the working face,the maximum subsidence value of the surface presents a trend of gradually increasing to stable,and the trend subsidence curve gradually changes from funnel-shaped to bowl-shaped.The trend of the trend subsidence curve is small,and the center line of the trend presents a symmetrical distribution.(3)Traditional observation methods can obtain accurate surface subsidence data,but not complete subsidence data of working face.InSAR has an advantage in monitoring subsidence boundary areas with small subsidence changes.UAV Lidar technology has advantages in monitoring the center of mined subsidence basins.The three methods can be combined to obtain a complete and accurate surface strike subsidence curve.(4)The maximum subsidence velocity of the surface in the five mining areas presents a periodic distribution,and the peak value of the subsidence decreases continuously and tends to be stable.When all working face mining is finished,501～ 505 working face to reach the reclamation time;The reclamation time is positively correlated with the advance of mining stage,and the reclamation time can be reached after the interval of 1.71 ～ 1.79 working faces.The reclamation area is 1284.25 hectares,accounting for 98.79% of the total study area...