Study On Optimization Of Deep Mining Sequence In Sifang Gold Mine

With the development of social economy and the increasing demand for mineral resources,deep mining has become the development trend of mining industry.Compared with shallow deposits,the "three heights" and "mining disturbance" of deep mines will bring a series of technical problems.During the transition period from open-pit method to caving method,the destruction of surface ecological environment caused by surface movement and deformation in Sifang Gold Mine has become the most serious problem faced by mining enterprises.Based on the engineering backgroundin Sifang Gold Mine,this paper studies the influence of different mining sequence on surface movement,deformation and stability of ore and rock by means of engineering geological survey,rock mechanics experiment,theoretical analysis and FLAC3 D numerical simulation.The main conclusions are as follows:(1)Through geological data and field engineering geological investigation,the rock mass of Sifang Gold Mine is classified by CSIR rock mass quality classification method,and the rock mass quality of Sifang Gold Mine is graded 72 points by RMRmethod.It is known that the rock mass of Sifang Gold Mine is classified as Class II and belongs to good rock mass.The mechanical parameters of rock mass are obtained by laboratory tests and the mechanical parameters of rock mass are obtained by Hook-Browncriterion.(2)Through the displacement analysis of different schemes,the maximum horizontal displacement is located above the both ends of the goaf,and the maximum vertical displacement is located in the direct roof of the goaf.For the upper and lower walls of inclined orebodies,the maximum horizontal and vertical displacements are located in the upper wall of the goaf.The location of maximum displacement is closely related to the shape,size and depth of goaf.(3)By analyzing the plastic zone of different schemes,the volume change of the plastic zone is linearly correlated with the depth of mining decline when the advancing direction of mining work is the same as the trend of ore body.When the advancing direction of mining work is the same as the dip of ore body,the volume of plastic zone is smaller when mining disturbance area of ore body is smaller.(4)Through the analysis of the influence of vertical stress of different schemes on the stability of goaf roof,with the continuous mining of stratified orebodies,the phenomenon of obvious stress redistribution appears in the roof and overlying strata of goaf.Among the four schemes,scheme 1 and scheme 2 are more favorable to the stability of the roof of goaf,in which the tensile stress is 1.46 MPa and 1.65 MPa,respectively.The maximum tension stress in the mining sequence of scheme 4 is 1.92 MPa,and the final goaf stability is the worst.(5)Applying the AHP-TOPSIS evaluation model method,four mining schemes are taken as evaluation sets and the main technical indicators involved are taken as index sets.Then the weight of evaluation indexes is determined,and the optimal mining scheme is obtained by comprehensive evaluation.