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In order to improve the recovery rate of open-pit coal mine resources, under the condition of studying the deformation and failure mechanism of the slope, the horizontal mining is carried out and the stope shape is optimized. Taking the Thar coalfield in Pakistan as the research object, the paper firstly analyzes the deformation and failure mechanism of the slope through FLAC3D, clarifies the landslide mode, and then analyzes the tracking distance of the horizontal mining and inner row, and finally provides a reference for the optimization of the coal mine. The results show that the failure type of the slope belongs to the tension-shear composite type, and the stability of the slope increases as a whole due to the double support effect of the slope working aid and the inner dump. When the tracking distance of the inner row is 50 m to 100 m, the three-dimensional spatial effect of the slope is significant, and the stability is high; as the tracking distance increases, the stability becomes worse and worse.

In order to study the characteristics of seepage and pore water pressure of an open-pit mine slope in the grassland area of eastern China under the near-natural restoration mode, this paper takes the SEEP/W module in GEO software as the parent item and fits the SLOPE/W module to simulate and analyze the characteristics of slope resistance to hydraulic erosion, the change of seepage path and the redistribution of pore water pressure under the condition of heavy rainfall in the mining area. The results show that after the anti-S-type reconstruction of the original internal dump slope, the resistance to hydraulic erosion of the slope is significantly improved, the slope angle of the upper and lower steps of a single step is reduced, the flow velocity of regional inner diameter flow is reduced, and the degree of rainfall infiltration is increased. Affected by the change of slope surface shape, water seepage occurs at all levels of the slope of the original inner dump slope, and the degree of water loss and soil erosion ishigh. After remolding, the seepage density of 15 m and 20 m bench remolding models increased, and there was no obvious water outflow on the slope of inner waste dump. The pore water pressure at the top of the slope is redistributed, the distribution range of negative pore water pressure is increased, and the area of the transition area is relatively uniform, which effectively alleviates the local ponding phenomenon in the upper rock stratum of the slope caused by the difference of permeability coefficient of different rock strata.

Based on the problem of tectonic structural surfaces existing in the end slope of huge thick coal seam open-pit mine, this paper uses the limit equilibrium method and numerical simulation to analyze the influence of tectonic structural surfaces of different sizes and positions on the slope stability during end slope mining. The results show that the existence of tectonic structural surfaces will reduce the stability of end slope, and the longer the structural plane and the closer it is to the bottom of end slope, the greater the impact on slope stability; the structural surface does not affect either the trend of slope stability coefficient variation or the transfer of maximum shear strain increment.

Aiming at the end slope deformation and instability caused by end slope coal mining, this paper is based on the mining engineering practice of end slope coal mining of open-pit mine in Ordos area of China, a three-dimensional numerical analysis model for rock mass movement failure of the end-slope mining field which is under near-horizontal condition is established, the whole process of “coal seam mining-formation of mining cave group-failure of support coal pillars-instability of slope rock mass”, the characteristics of movement and failure of coal pillar and rock mass of slope are revealed, the key positions and trigger conditions of slope deformation and instability are proved. Based on the study of characteristic law, the bearing model of supporting coal pillars in end-slope mining field is constructed, based on the theory of sharp point mutation and safety factor evaluation method, a method to judge the stability of supporting coal pillars is proposed. The engineering application results show that this method can further improve the recovery rate of end slope pressed coal to more than 60% on the premise of ensuring slope stability.

In order to explore the stability change law of the south slope during the process of the inner dumping pressure foot in the south open pit coal mine in Xinjiang, this paper studied the dynamic change law of the slope stability during the process of the inner dumping pressure foot in the south open pit coal mine by means of numerical simulation and theoretical analysis. Firstly, the FLAC3D strength reduction method was used to simulate the process of the inner dumping pressure foot in the south slope, and the variation rule of the potential sliding surface position and stability coefficient in the process of the inner dumping pressure foot in the south slope was obtained. The optimal geometrical parameters of material cross section in the south side of the southern open-pit mine are obtained. Based on the numerical simulation results, the limit equilibrium theoretical model of the inner dumping pressure foot in the south slope was established, and the calculation formula of the stability coefficient of the middle south wall in the process of the inner dumping pressure foot was deduced. The evolution law of slope stress in the process of pressing foot in the south slope is expounded and the mechanism of the change of the position of the potential slip surface and the improvement of the stability of the middle south wall in the process of the inner dumping pressure foot was expounded.

Open-pit mine step height increase has positive significance for the enterprise, but the material of the dump is heterogeneous and discrete, and the mechanical properties of the lower materials are different with the increase of the height, so, it is necessary to refine the evaluation of the safety and stability of the slope while improving the height of the soil dumping step, and to optimize the height of the step from the perspective of safety. In this paper, the mechanical properties of the material under different consolidation pressures are obtained through laboratory test and numerical simulation of the material obtained from the dumping site of the open-pit mine in Tianchi Energy South Open-pit Mine, Xinjiang. By means of DEM numerical simulation, the change rule of the safety and stability coefficient of the dump steps in different areas and at different heights was obtained. The results show that with the increase of consolidation pressure, the degree of internal cementation and the mechanical strength of the sample increase. The instability of the inner dump slope will lead to circular arc landslide, which is characterized by uneven settlement at the top of the slope in the initial stage, and a large amount of slope particles rolling down in the later stage. When the strength reduction exceeds the safety stability factor, the velocity of the particles on the slope will change abruptly. The safety and stability coefficient and the step height change as a logarithmic function. The stability of the bottom dump step is better than that of the common dump step, and the bottom dump step cannot maintain stability when the height is 75 m.

Taking the gangue dump of Lijiahao Coal Mine as an example, this paper makes a comprehensive study on the stability of the gangue dump slope. For the problem that granular gangue cannot be directly made into samples to test mechanical strength parameters, the mechanical parameters of granular gangue are inverted by simulation software PFC3D, and the shear strength parameters of granular gangue are obtained by lateral compression test and triaxial compression simulation test. Using the shear strength parameters obtained from the experiment, the stability of the gangue dump slope of Lijiahao Coal Mine is analyzed by FLAC3D numerical analysis software. The safety factor is around 1.2. The calculation results show that the slope of the gangue dump is in a relatively stable state temporarily. According to the displacement contour, the protection area should be concentrated in the upper two steps, which can effectively avoid local instability. At the same time, in order to ensure long-term stability, combined with the characteristics of gangue, the corresponding effective control measures are proposed.

This paper aims at the problem of slope deformation and instability induced by the water from the burnt rock aquifer seeping into the basement of the dump. Taking the slope of an open pit mine in Xinjiang as the background, the water seepage law of burnt rock aquifer in the slope and the deformation and movement law of rock and soil mass in the slope are studied by numerical simulation method, based on the method of ultimate bearing capacity estimation under the condition of very thin topsoil and thin topsoil basement, the ultimate height of the inner dump was determined, the limit equilibrium analysis method is used to optimize the soil discharge parameters of the inner dump. Through the research, the discharge parameters of the soil dump in the weak basement under the influence of groundwater infiltration are determined.

In order to solve the problem that the surface subsidence coefficient of shallow buried coal seam is difficult to determine in northern Shaanxi mining area, the data of surface rock displacement parameters in coal seam mining under different topographic conditions are collected in this paper. On the basis of analysis, three main influencing factors affecting the surface subsidence coefficient of the mining area are obtained, that is the ratio of bedrock thickness and overburden thickness JZ, the ratio of bedrock thickness and mining height JC, slope stability G. In addition to, taking JZ and JC as independent variables and combining topographic forms with piecewise function, the expression of surface subsidence coefficient is given respectively. The research results show that the surface subsidence coefficient of loess gully region should be mainly calculated by JZ, and the ratio of the height of the slope to the overall thickness of the loess cover should be considered. The JC of the ground surface subsidence coefficient should be calculated at aeolian sandy site. Through two engineering examples, the reliability of the piecewise function expression of surface subsidence coefficient with JC and JZ as independent variables is verified.

To improve the accuracy of the modeling and stability evaluation of the waste dump, the theoretical analysis is conducted on the remolding load produced by different operation modes of the waste dump. Combined with the compressive deformation characteristics of pore structure, the growth mechanism of shear strength of rock and soil in the remolding process is revealed. Based on the actual production of Shengli Open-pit Mine, this paper puts forward the method of inclined stratification of internal waste dump and horizontal stratification of external waste dump, and analyzes the influence of stratum division on the evaluation result of waste dump stability. The results show that the stability coefficients of the internal and external waste dumps are 6.2% and 30% higher than those of the traditional waste dumps, respectively, and the difference of stratum mechanical parameters results in the overall upward migration of the potentially dangerous slide surface.

This paper analyzes the slope stability of inner dump covering end-slope after the end-slope mining of a domestic open-pit coal mine by means of theoretical analysis and numerical simulation. Firstly, the theoretical model of inner dump covering end-slope is established from two-dimensional view point. At the same time, the calculation formula of slope safety factor after inner dump covering end-slope is given, and the mechanism of slope safety improvement in this process is expounded. Then the numerical analysis software FLAC3D is used to analyze the stability of the end-slope without inner dump after the end-slope mining, and the process of inner dump covering end-slope is divided into three stages. According to the simulation results, the follow-up of the inner dump obviously reduces the shear strain increment of end-slope rock, and the deformation range and amount of rock also obviously reduce. Therefore, the inner dump can effectively improve the slope safety. Especially, in the early stage of the inner discharge work, the effect of increasing the stability of the end-slope is the best.

Landslide is one of the most common geological hazards in China. After nearly one hundred years of research by many scholars, the theory of slope stability calculation and evaluation, safety prevention and control measures and prediction theory have made qualitative leap and improvements. The relevant design and construction codes are relatively comprehensive, and the relevant limit in slope stability evaluation is also relatively high. Balanced calculation theory, geographic information system, numerical simulation and other methods are improving day by day, which fully and systematically guarantee the safety of various large-scale construction projects. However, due to the level of knowledge of the times and the special material responsible for geological structures and engineering geological components, the complexity of spatial variability cannot completely solve the current work. In this paper, the shortcomings of slope stability evaluation, the future development direction and the problems to be solved are analyzed and discussed.

Surface deformation caused by mining in mountainous areas is complex and special, and surface damage is often caused by many factors. In view of the fact that conventional monitoring methods can not accurately determine the causes of abnormal building damage, taking the mining of 15110 working face Baiyangling Coal Mine as an example, taking SBAS-InSAR as a technical means, with the aid of Sentinel-1 data of 8 scenes, the spatial distribution characteristics of surface deformation in the study area are interpreted and the causes of housing damage. In this paper, the differences between the interpreted surface deformation and the existing subsidence laws are analyzed, and the influence boundary and time series subsidence characteristics of mining area are analyzed. It is concluded that the slope stability changes due to the uneven movement of the soil in the mountain area, and the slow sliding of the slope due to the presence of the component of the soil self-weight is the main cause of the damage to the village buildings.