Influence Of Underground Mining On Bedding Slope Stability

Excavation of underground engineering with complicated topography and geology condition, especially under hilly area, may bring about deformation and failure of overlying strata and cause a series of geological hazards like landslides, cracks, collapses, subsidence and so on. Among them, mining landslide is the most striking problem, which seriously threatens people’s life and property safety. Thus, research on the mechanism of mining landslide is of great significance.Based on one iron mine in Chongqing, this thesis takes advantage of the actual topography, geological structure, regional geological background and other basic conditions, applying UDEC software to study of models with convex shape and reverse S shape after mining, analyzing the change law of stress-strain as well as the deformation and failure law of overlying strata. In addition, the stability coefficient of slope body after mining with different mining height is calculated by theoretical analysis to discuss and evaluate slope stability. Furthermore, similarity model experiments are conducted to study the deformation and failure law of slope body.The main research outcomes are as follow:①The results of numerical simulation indicate that there are tensile stress areas in the strata near the ground surface. Concentration distribution of tensile stress exists above the goaf edge and the higher mining height leads to more obvious concentration. Besides, there are clear oblique cracks between the area over the goaf edge and the slip surface. The higher the mining height is, the more obvious the crack development is. In addition, the influence of underground mining on the slope body with convex slip surface shape is concentrated on the middle-lower part of the slope body while there are clear vertical cracks on the upper part of the slope body with reverse S slip surface shape. Moreover, as the result of underground mining, the slope body turns to move to the direction of goaf and downslope area. The higher the mining height is, the lower the shear strength of slip surface is, the bigger the move and deformation values are, and the lower the slope stability is.②Seen from the theoretical analysis, it is slight mining as value of mining intensity is less than 1. As the mining height decreases, the value of stability coefficient decreases. When the mining height increases to 2.4m, the stability of slope body with reverse S slip surface shape turns to critical state. Furthermore, due to the bigger mining area, the decrease trend of slope stability of reverse S slip surface shape is more obvious that of convex slip surface shape.③In the similar simulation experiments, landslides do not happen involved the two slope models of convex and reverse S slip surface shapes. However, when the mining height increases to 2.4m, there are collapses in a small range under the two different conditions. Meanwhile, because of the bigger area of mining, the crack development of reverse S slip surface shape is more obvious than that of convex slip surface shape. In addition, the subsidence value and horizontal displacement value increase as the mining height increases, and the max subsidence value of reverse S slip surface shape is higher than that of convex slip surface shape. Thus, those outcomes indicate that the influence of underground mining on slope model with reverse S slip surface shape is more obvious than that with convex shape, which leads to the lower stability.