Analysis Of The Influence Of Underground Coal Mining On The Stability Of Surface Slope

In recent years,with the need of economic development in China,the intensity of coal resource mining is increasing,which leads to the geological disaster of unstable landslide caused by underground mining in coal mine area.The unstable landslide induced by underground coal mining is a gradual failure process,and its failure mechanism is complicated.In the existing underground mining conditions,the dynamic characteristics of loess and the influencing factors of mining disturbance are ignored in the research results of surface loess slope stability,and the surface loess landslide is regarded as a statics problem during mining.Implicit algorithm is used to solve the safety factor.Therefore,on the basis of considering the dynamic characteristics of loess and combining with the explicit finite element dynamic large deformation analysis method,this paper carries out the research work on the stability of surface loess slope during underground coal mining.The analysis method of surface slope stability in coal mining process is put forward.Based on the instability of surface loess slope induced by underground coal mining in Huangling mining area of Shaanxi Province,this paper systematically analyzes the influence of underground coal mining on surface slope stability.The main findings are as follows:1?Through reading the relevant literature,the research results of underground mining slope at home and abroad are summarized,and the research status and development level of surface slope stability under the action of underground mining are reviewed.This paper analyzes the failure mechanism,failure mode and analysis method of surface slope in the existing underground mining process,and thinks that the surface loess landslide belongs to the dynamic large deformation problem in the underground mining process.Therefore,the method of stability analysis of underground coal mining slope considering mining disturbance and soil dynamic characteristics is proposed,that is,explicit finite element large deformation analysis method.2?The visco-elastic-plastic constitutive model of loess is established.A visco-elastic part of the loess constitutive model is established by using dampers and springs in parallel.The Mohr-Coulomb strength theory is taken as the plastic part of the dynamic constitutive model,and the dynamic visco-elastic constitutive model of loess is established in series with the visco-elastic part.The prediction results of this model are compared with the results of dynamic three-axis test to verify its rationality.3?The dynamic constitutive model of loess is combined with the explicit large deformation finite element method.the slope safety factor determined by the explicit finite element method is compared with the slope safety factor solved by the explicit finite difference method and the implicit finite difference method.The results show that this method is suitable for the calculation of slope safety factor.4?The explicit finite element analysis method is used to study the stability of surface loess slope during underground coal mining.Taking Huangling Mine as engineering background,combined with engineering geological exploration data and physical and mechanical experiments of rock and soil,the mechanical parameters of rock and soil were determined.The dynamic variation law of slope safety factor during mining is analyzed by using explicit finite element large deformation calculation program.The influence of mining advance,mining speed,mining thickness(thickness of primary mining coal seam),slope slope and height on the stability of loess slope is studied.The results show that different mining scale,mining speed,mining thickness,slope height and slope have great influence on slope stability in the range of mining disturbance,but the influence range of mining disturbance is independent of mining speed,mining thickness,slope height and slope slope,which is only related to the location of goaf.The evaluation model of the influence of underground coal mining on the stability of the surface slope is established.Through the safety factor to evaluate the stability of the surface loess slope,the maximum advance of underground coal seam excavation is obtained under different mining conditions and different engineering conditions.