Study On Overburden Movement Law And Slope Stability Control Method In The End Slope Mining Field Of An Open-pit Mine

Due to the limitation of technology and safety,the amount of coal resources pressed under the end slope in open-pit coal mine is huge,with the completion of internal drainage and reclamation,most of these trapped resources will become permanent losses.How to realize the efficient recovery of these resources on the premise of ensuring the stability and safety of the slope has become an important subject in the development of mining technology in China.In this paper,based on the engineering background of the end slope coal mining of typical open-pit coal mine in Ordos region and Pingshuo mining area,methods and means such as field test,numerical simulation,model experiment and theoretical analysis are comprehensively used to systematically study the overburden migration law and slope stability control method in the end slope mining field,and the main research results are as follows:(1)Based on the coal mining at the west end-slope of the first mining area of Delong open-pit mine in Ordos area,the failure process of structure and weakening law of strength properties of rock mass in the end slope mining field under the coupling action of "slope stress field" and "roadway group stress field" are revealed,based on non-contact measurement of rock mass structural plane,Monte-Carlo stochastic simulation,Hoek-Brown rock mass strength reduction and numerical analysis,a dynamic evaluation method for slope stability of the end slope mining field is proposed.(2)A two-dimensional / three-dimensional integrated simulation experiment device for end slope coal mining is developed,and a research model of coal pillar failure and slope instability by end slope coal mining under near-horizontal condition is established.The model experiment and numerical analysis are combined to simulate the whole process of ’ roadway group formation-supporting coal pillar failure-slope rock mass instability ’.The stress and deformation law of supporting coal pillar and overlying rock mass are revealed,the dynamic disaster process and occurrence mechanism of landslide in the end slope mining field are proved.(3)The simplified model of ’ coal pillar-roof ’ system,the vertical load distribution model of coal pillar and the mechanical analysis model of ’ roadway-surrounding rock’ are constructed,the calculation method of peak stress and the width of plastic zone of coal pillar are proposed,and the stability criterion of supporting coal pillar in the end slope mining field is established,which provided a theoretical basis for the reasonable setting of supporting coal pillar.(4)The research model of the influence of key factors on the movement and deformation of the mining slope is established.Through comparative analysis,the influences and differences of pillar width to height ratio,overall slope Angle,mining depth and filling mining on the stability of coal pillar and overburden are revealed.(5)The stability control method of overlying rock based on reasonable mining parameters in the end slope mining field is proposed,the applicability of mining parameters is studied by taking the coal mining of No.9 coal seam at the southern endslope of Antaibao open-pit mine in Pingshuo mining area,the reliability of the research results is verified by the combination of slope stability dynamic evaluation and surface deformation monitoring.