The Design Of Optimization Shape Of Deep Furrow Fit Slope

With the fast increasing of the demand for the mineral resources because the development day by day at full speed for the domestic and international industry, shallow ore resources of a lot of open pits are almost totally exploited, they begin to exploit deep ore resources and change over to furrow mining, therefore, the mining procedure and ore body deposit terms become very complicated, the waste-to-ore ratio increases rapidly, the open form design of slope to compose exploit and economic benefits of mine become increasingly important.The traditional methods of slope angle design and safety coefficient evaluation of open pits are simple, and do not accord with the characteristic of the deep and concave open pit very much, therefore, certain irrationality exists. According to the theory of the space-time principle of reducing overburden amount in deep open pits put forward by my tutor, under the real conditions of geology and production in the small north open pit, Jinduicheng Molybdenum Co., this paper researches into the reasonable shape of slope in the cases of different depth, size and rock properties etc. and develops the curved line equation of slope on oval's long and short ends in vertical section. The result shows that, comparing with the traditional methods, the rational slope angle calculated by new method can be steeped, therefore, the overburden amount reduces more than 40 million tons. Using the software FLAC-3D, under the same geologic condition, the stresses in the rock mass of the slope, both the design and the calculated by the new method, are calculated. The result shows that because unreasonable shape of slope designed by traditional method, uneven physical strength and concentrated stress appeared when it begins to exploit deep ore. Especially the four bands appear straight-line shape, they are like to be developed into slipped slope under the tension stress in the middle of the bands. Which causes unstable factors to slope and adverse effect to production; the rational slope designed by new method conformity to mechanical theories, this shape can averts concentrated stress caused by upper rock gravity, contemporarily, the stress distributes along the oval ring section, so the integrate stress distribution around slope become more even and reasonable and the stability also be improved than the traditional.The result not only proves that reasonable shape of the deep pit slope is changed from gentle in the upper, to steep in the lower, in vertical section, and circular or oval in horizontal accords to mechanical theory and also illustrates this shape is utilitarian through digital simulation calculate. The research result can offer a reference for determining the shape and the slope angle in other deep pits, make the mines realize optimizing mining, improve the economic benefits and social benefit on the premise of safety production.