Study On Instability Mechanism And Stability Evaluation Of Slope Under Mining Disturbance

Coal resources play an important role in ensuring the safe supply of energy and supporting economic and social development in China.With the continuous mining of coal resources in China,more and more slopes are destabilized by underground mining disturbances,which seriously threaten the safety of people’s lives and properties in mining areas and the safe production of coal enterprises.Therefore,the destabilization mechanism and stability evaluation of mining slopes have become an important research topic at present.In this paper,two common typical slope types,namely,mining rocky slope and mining loess slope,are selected as research objects,and various technical methods,such as literature research,theoretical analysis,numerical simulation,and field measurement,are used to study the mechanism of slope deformation and stability evaluation under coal mining disturbance.(1)A preliminary model for determining the instability of mining laminated rock slopes was established.Scientific and reasonable classification of mining slopes based on different classification indexes was carried out using literature research,and the typical mining slope instability patterns in China were analyzed.By combining orthogonal experiments with numerical simulation,the change law of slope safety coefficient under different mining conditions of gently inclined laminated rocky slopes is analyzed,the orthogonal test results are subjected to extreme difference analysis,and the importance of influencing factors is ranked in order of importance,and the results show that the order of importance is: location of mining area > rock production > direction of workface retrieval.Based on the key stratum theory,the equation of equivalent load is given by equating the overlying rock stratum load to the superposition of uniform load and linear load,and then the equation of maximum bending moment and maximum tensile stress for the key stratum and soft rock section is derived,and the damage law of rock stratum is analyzed by strength condition,to get the fracture zone height.The preliminary judgment model of mining laminated rock slope instability is established,and a mining landslide in Guizhou Province is used as the background to establish a numerical model to analyze the change characteristics of rock movement and plastic zone during the coal seam mining process,which verifies the feasibility of the preliminary judgment model of slope instability.(2)Revealed the destabilization damage mechanism of loess slope.The surface subsidence caused by top coal caving mining in loess valley terrain was measured,and the surface movement characteristics and related parameters were analysed and studied.A 3D model of the considered terrain was created by using the Rhino software and imported into the 3DEC software for numerical simulations.The movement of rock formations during mining and the evolution of plastic damage within the valley are analysed.The results show that the surface movement of 1313 working face is intense.The starting distance of surface subsidence is less than 30 m.The leading infection distance is73 m.The leading infection angle is 68.7°.The strike boundary angle and the upper boundary angle are 40.3°,and the strike movement angle and upper movement angle are 37.8°.The dangerous movement range with the horizontal tensile deformation of 2 mm/m as the movement boundary is significantly larger than the surface movement basin range determined by the subsidence value of 10 mm.Numerical simulation is used to analyze the mining slip process in loess valley terrain: when the working face is retrieved 30 m along the strike from the open-off cut,the stress equilibrium of the rock around the mining area is broken,and the top plate is shear damaged by the self-weight and the load of the overlying rock layer,and the rock around the mining area is plastic yielded;when the working face is retrieved 120 m,the coal seam is in the non-full mining stage,the shear damage zone of the rock at the bottom of the beam mount is penetrated,and the slope is sheared to the neighboring empty side under the action of gravity.Compared with the section with the surface slope of 15°,the maximum horizontal movement in the negative direction of the X-axis of the section with the surface slope of 18°and 22° increases by 107.3% and 246.5%.(3)A mining slope stability evaluation model was constructed.In this study,seven evaluation indexes were selected,and their influence mechanisms were analyzed to establish a system of evaluation indexes for the stability of mining slopes in Xing County,Shanxi Province,China.A new evaluation model for the stability of mining slopes was established based on the interval analytic hierarchy process(IAHP)to determine the subjective weights of the indexes and the improved CRITIC method to determine the objective weights of the indexes,which circumvented the limitations of subjective or objective weights by combining the minimum discriminating information.The model was applied to the mining slopes in Xing County,Shanxi Province,and the results showed that slopes A,C,D,and E were in an unstable state,slope B was in an understable state after mining.Finally,the accuracy of the evaluation results was verified through field surveys.The model has engineering application value in predicting the stability of mining slopes and can provide theoretical suggestions for later slope management to ensure the safe production of coal mines.Figure [28] Table [16] Reference [95]...