| Ning Du Pyrite is a kind of gently inclined ore body, which is hard to exploit, at present the miners don’t have the unified methods to exploit the mines, and there are low safety factor and extraction rate as well. In order to achieve the exploitation of high efficiency, security and economy, it is first and foremost to choose exploiting ways reasonably andoptimize the parameters of stope structure. A Selection of exploitation has been made in this article, using level analyis and a fuzzy mathematics comprehensive method, and through the way of calculation and numerical analysis, the parameter of stope structure and the extraction order are optimized. The main conclusions are as followed.(1) Applying the Analytic Hierarchy Process(AHP) and Fuzzy Mathematics Principle, build a comprehensive evaluation model of exploitation scheme about Ning Du Pyrite, and have chosen the best mining scheme scientifically as well. In the process of optimization,miners think over all kinds of factors which may affect mining scheme, and make use of AHP to ensure the weight of all kinds of evaluating indicators, and judge comprehensively to the alternative mining plan using the fuzzy mathematics principle, finding out that the room-and-pillar method is the best one.(2) Regarding the safety factor as an evaluation index of pillar stability to sort the sensitivity of the factors affecting the stability of pillar with using orthogonal polar difference analysis, finding out the sensitivity of room span and pillar size most. Through empirical formula of the photoelastic test conclusion and calculation, we can get the ultimate span of chamber. And on the basis of that, establish the pillar instability mode with the cusp catastrophe theory to obtain a critical pillarwid.thusing the theory of area bearing capacity,we can to deduce that there can be thesmallest measurement to pillar. Integrating the means of elastic mechanics, structuremechanics and material mechanics to get the thickness of pillar under the different pillar span, and matching the results, pushed out the proper relation expression of the span and thickness of the pillar. Finally, the limited span of chamber is 14.22 meters, the width of the smallest pillar is 3.99 meters, and the thickness of the top pillar is 3 meter, providing the reference to chamber imitation in the future.(3) According to the results of the practical field and theory calculation, we can determine the combination of the structure parameter in different chamber using orthogonal test,making use of the softwares named ANSYS and FLAC3 D to imitate in different chamber.compare stress, displacement and plastic zone of chamber key parts of different schemes to choose the plan of safe stope, consider the stress, displacement, plastic zone and recovery rate of the key parts in stope as the evaluationindex of superior degree of each scheme to establish the comprehensive evaluation model and determine the weight of each index, turning out that when the span of chamber is 14 meters, the distance of the pointed pillar is 7meters, and the thickness of the pointed pillar is 6 meters, the thickness of top pillar is 3 meters,the stability and tech-economy are the best. And on the basis of that,we optimize the order of extraction, compare the change of stress, displacement and plastic zone with recovery steps of different extraction sequence scheme, turning out the extraction sequence from the wings to the central best.(4) Established the monitoring network of stope stability of the Ningdu pyrite mine, analysis the results of pre monitoring and verify safety of the stope of the optimal scheme. |
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