The Deformation And Stability Analysis Of High Open Pit Slope In Complex Faults Zone During Excavation

Slopes of open pit mine are characterized by high altitude, steep angel, long service time and serious hazard. Besides engineering geological conditions of the mine are usually very complex and vary greatly in different slope sections, together, the stabilities change dynamically along with the mining process. All these factors make the stability of the slopes especially outstanding and common. The stability of the slopes continuously decreases with mining, and if no effective treatments are carried out, landslides and collapses might be occurred, which will cause failure to the mining operations as well as maintenance work of slopes. In this study, taking the high slope in E district of the Baiyumebo Iron Mine as an example, based on the field surveys, investigation data, by means of geological analysis, limit equilibrium calculation, and numerical modeling(finite difference method, FLAC3D), the deformation features and stability of the slope under the condition of unreinforcement and reinforcement. The main research work and principal results are as follows:(1)The geological structure characteristics and potential failure mode of the slope are determined. Based on detailed field survey of the structure of the slope rock mass, the lithology, structure characteristics and hydrogeology of slopes in different areas are determined. And then incorporation with plane projection analysis, the influences of faults and joints on slope stability and failure modes have been described.(2) The deformation and stability growing trend of the slopes(without reinforcement) until mining to bottom have been analyzed by numerical modeling. A three-dimensional model of the slopes in E district is built, according to the geological features and excavation scheme, and the excavation process from original ground surface to the bottom has been simulated. The stability of the slopes during mining has been analyzed based on the tress field, displacement and plastic zone. The stability in different excavation stages is also analyzed. Thus, the potential collapse zones have been detected during the whole mining process, which provides the basis for further stability analysis and design of manage scheme.(3)The limit equilibrium calculation of the slope stability during mining has been carried out based on the stability prediction results, and design scheme of slopes at present stage taking into account the subsequent excavation. The potential failure zone and collapse mode of slope in E district(1514-1645 m) at present stage are determined based on the numerical modeling and limit equilibrium calculation. And combined with the stability analysis of the slope in subsequent excavation process, the area needed to be treated and treatment scheme are determined. The scheme and effectiveness are also analyzed by numerical analysis and limit equilibrium method.(4)The stability of slopes in subsequent excavation after reinforcement in present excavating stage has been studied and management area is recommended. On the premise of the effectiveness of the treatment in present excavating stage, the stability of slopes in subsequent excavation has been analyzed, and the potential failure area has also been predicted, and finally, the governance areas and corresponding treatment scheme are put forward.