Research On The Optimization Of The Angle Of Final Pit Slope In Sijiaying Iron Mine

Luanxian Sijiaying Iron Mine of Tangshan Iron and Steel Co. Ltd. is a new oversize mining enterprise. As the deepest open pit occurring, the final slope will reach 400 ~ 500 meters depth. Whether the final slope angle is reasonable or not, it is very important to put emphasis on the effect on mining safety and on the economical benefits of the whole mine. Therefore, the optimization research on the angle of final slope in Sijiaying Iron Mine can make an opportunity for taking preventive measures and making great significance to the enterprise.Based on a detail analysis of geological data of the mining project, the rock slope internal friction angle, cohesion and other mechanical parameters can be gained by the on-site investigation and using the engineering analogy. Because the ultimate slope is higher, the length of service time of the upper and lower part of the slope and the rock mass strength of various terranes varies widely. Therefore, research on the optimization of the angle of final pit is bounded by terranes boundary. The slope angle is considered separately. Seven kinds of feasibility programs will be analyzed.The slope stability of the various programs is analyzed by using the shear and shear strain contours, most non-equilibrant history records of profile, horizontal displacement field graphs, plastic state diagram and envelope of failure for the various terranes which are made by the FLAC software.The slope stability safety factor from the method of limit equilibrium is applied to verify the reliability of the numerical simulation's analysis results. The data show that the results of two methods are mainly consistent, but the safety factor calculated by numerical simulation is less than that calculated by the limit equilibrium method. It shows that the method of numerical simulation is a practical and reliable method in slope stability analysis, which can not only visually describe the regularity of internal stress and strain of the rock slope, but also track the displacement of the model elements and the conditions of the largest imbalance force with the time-varying. Meanwhile, it can provide the safety factor which usually used to evaluate the slope stability.Through the optimization analysis of various programs, it is the best to take the optimization program for Sijiaying open pit iron mineⅡ, and the final slope angle of western slope is as follows: the slope angle of quaternary system layer is 32°, the slope angle of the sinian layer is 45°, the slope angle of pre-quaternary system layer is 47°.The whole slope angle of final slope pit of is 44°.