Study On Multi-factor Influence Analysis And Optimization Technology Of Yichang Phosphate Mines Mining

Because of the obvious structural fracture and joint fissure,complex and diverse topographic structure,fragmentation of ore and rock and poor stability of Yichang Phosphate Mine,a series of geological hazards,potential safety hazards and environmental pollution had been caused by traditional mining technology.The main manifestations are as follows:roof collapse and side wall collapse are frequent;goaf collapse and surface cracking are constantly occurring;peak collapse and landslide occur from time to time;Ground pressure activity caused by goaf is becoming more and more frequent.A large number of mine waste water carries suspended substances containing phosphorus into surface water,which causes water eutrophication and serious environmental pollution.Therefore,in view of the above problems,this thesis carried out research work by means of on-site investigation,theoretical analysis,laboratory test,numerical simulation,on-site test,comprehensive evaluation and other technical means.(1)In this thesis,the joint fissures and triaxial compression mechanical properties of broken phosphate ore bodies in Yichang area were analyzed systematically.By establishing the equivalent coupling damage variable model of triaxial compression,the damage characteristics of fractured rock mass under different confining pressures were studied.Based on these studies,the relationship among joints,cracks,confining pressures,damage characteristics and mechanical strength of fractured rock mass was revealed.Aiming at the problem that the parameters of fractured rock mass are sensitive to the stability of stope,the orthogonal-gray correlation evaluation model(OED-GRA)was used to study the correlation between the rock mass parameters and the stability of the stope.In addition,the correlation degree between rock mass properties parameters of Hoek-Brown criterion and rock mass mechanics parameters of Mohr-Coulumb criterion was obtained,all these can avoid the deviation of the results of stope stability analysis caused by the deviation of rock mass parameters.(2)Aiming at the problem of poor accuracy of in-situ stress inversion analysis under complex geological conditions,the multiple regression analysis of functions superposition was put forward that the regression data were high relevance with the measured value and closer to the engineering practice,which avoid the problem of poor fit and high deviation in regression analysis of single type function.Based on 3Dmine-MIDAS-FLAC3D software,the numerical calculation model of whole mine under complex geological conditions was established,and the boundary stress that nonlinearly changed with depth was performed through stress loading procedure with the multiple function regression equation by use the fish language.By simulating and analyzing the deformation and stress distribution characteristics of different advancing sequence of open stoping method and filling method under complex topographic structure and stress environment,the laws of mining influence mode,overburden movement characteristics and failure forms under complex topographic condition were revealed,and the mining scheme and mining sequence were optimized.(3)Based on the characteristics of goaf group in Yichang Phosphate Mine,the thesis systematically constructed a three-dimensional spatial mechanical model of roof and pillar.By introducing the theories of elasticity and structural mechanics,it deduced the curve equations of the central subsidence deflection of roof under three boundary conditions and the mechanism of group catastrophe in goaf from the perspective of energy conversion,and established the calculation process of catastrophic instability in goaf group system,deduced the creep differential equation of goaf group roof,which realizes accurate prediction of instability rule and stability time limit of goaf group.The validity of this method was verified by example calculation and numerical simulation analysis.In addition,the factors of system instability of goaf group were analyzed comprehensively.The stability of goaf group can be predicted and controlled by adjusting the parameters of influence factor,which provided a reliable basis for optimizing stope parameters,searching for the best filling time,controlling the stability of goaf group and managing potential safety hazards.(4)Aiming at the characteristics of multiple attribute decision making of mining schemes under complex conditions,such as diversity of correlation degree and interval fuzziness,etc.,this thesis proposed a new comprehensive evaluation model of IVIFE-SPA-TOPSIS.Basing on the theory of interval fuzziness entropy and set pair analysis,and with a dialectical view of unity of opposites on certainty and uncertainty factors of the evaluation set,the model quantified correlation degree among the same,different and inverse angles of evaluation set at the first place.Secondly,the model introduced the game theory to optimize the weight determination method,considering both subjective and objective weights.Finally,the model combined the grey relational theory with the improved TOPSIS model,which not only reflects the position approximation relationship between data sequences,but also reflects the morphological differences among data sequences.Through case analysis,it realized the combination of qualitative and quantitative research in evaluation decision-making,statistical data and empirical theory,systematic thinking and hierarchical structure,determined the grade of multi-attribute schemes for stope structural parameters,calculated the closeness between evaluation index and positive ideal solution,and obtained the optimal stope parameter scheme.(5)In order to solve the problems of roof collapse,goaf collapse,aquifer destruction,water environmental pollution and low recovery rate of resources in the process of mining,a two-way slicing strip backfilling mining method was proposed,which improved and optimized the six major processes of top mining,roof control,slope protection,bottom mining,filling and roof contact.After the stope was mined and supported,the multi-layer,multi-media and multi-mode coupling filling technology were adopted to optimize filling,roof jointing,retaining wall and other construction techniques,so as to improve filling effect,efficiency and benefit.In order to solve the problems of time-consuming,cost-consuming and unsafe filling construction,measures such as bag filling and point-pillar supported roof method were put forward to realize safe,efficient and economic mining.Besides,this thesis also analysed the influence of mining methods on aquifer damage in Yichang Phosphate Mine,and put forward comprehensive control measures for the impact of mining on the hydrological environment,so as to reduce the environmental pressure in the mining area and increase the economic,environmental and social benefits of phosphate mining.