Mechancial Properties Matching Of Ground-backfill And Subsidence Control Of Backfill Mining Under Inundation In Zhongguan Iron Mine

As we all know, mineral resources are the material basis for the survival and development of human society. Along with the rapid population growth in our country and the rapid development of industrial and agricultural production and science and technology, the supply and demand situation is becoming increasingly serious, restricting the sustainable development of economy. Currently, the mineral resources are been exploiting in an unprecedented scale and intensity in our country, resulting that ore bodies of easy mining and good mining condition have been exhausted or being mined with the increasing scale of underground mining. Therefore, mining gradually shifts to the "three under" ore bodies and deep ore bodies. The negative effects of mining safety and the environment caused by mining have become increasingly prominent because of congenitally deficient of China’s mining industry, the weak research foundation of mining technology, weak environmental awareness. Filling mining is an important part as a system of green mining, which is one of the mining technology solutions under complicated conditions. In order to solve the safety problem under water, based on the research and analysis related to the existing research results and taking filling mining in ZHONGTIE iron mine as engineering background, this thesis mainly carried out the following research works:(1) Material proportioning and formation mechanism of backfilling consolidateThrough field sampling and laboratory test, analysis of the physical properties of filling material proportioning tests are carried out, revealing the mechanical properties, micro structure analysis of filling body and formation mechanism of backfilling material, optimizing the ratio.(2) The combination model stability analysis of ore-filling bodyThe effects of different width and the strength on the combination model stability of ore-filling body were carried out using the numerical simulation software.(3) The effects of stope structure parameters and mining sequence on the stope stabilityStope surrounding rock quality evaluation of was carried out. Based on the Zhongguan iron mine, reasonable stope structure parameters and stoping sequence were determined through a comprehensive understanding of stope stress and deformation law in the mining under process different stope structure parameters and stoping sequence by using a numerical simulation software.(4) The interaction mechanism between filling body and surrounding rockThe response mechanism of filling body and stope roof and lateral rock mass and time effect of filling body and the surrounding rock were analyzed, revealing interaction mechanism between filling body and surrounding rock. Then designed the filling body strength of dynamic matching, guiding the optimization of ratio of packing material(5) The surface subsidence prediction of filling miningBased on research in underground geological data and the buildings distribution, the surface subsidence was forecast after filling mining and evaluated its effects on buildings on the ground surface.Through a large number of site investigation measurement, laboratory testing, numerical calculation and theoretical analysis, around the two key issues of Zhongguan iron mine’s filling mining,which is backfill rock matching and settlement control,this paper expand a series ofresearch on gangue cementitious material ratio and filling tailings and gelation mechanism, stability of pillar-stable backfill combined model,stope mining sequence and structural parameters’ Influence on stope stability, interaction mechanism of backfill agaist rock and design of filling body strength matching,impact on the building by surface subsidence caused by filling mining,etc. And achieved the following conclusions.(1) Filling material is the basis for the mine were filled. Zhongguan iron mine use tailings-gangue cemented filling material to fill due to the high quality of iron ore and less tailing after mining, as well as the accumulation of problems near the mine waste dump. In order to guide the filling material ratio, we measured the fineness of cement, standard consistency water and setting time in the laboratory, as well as analysing the main components of tailings and gangue, and measuring their density and fineness. We used coal gangue cement filling materials to replace part of cement when cement filling material ratio, compared with a total of 20 kinds of programs. We initially preferred a water-cement ratio of 0.44, coal cement replacement ratio of 20% as the optimal ratio according to backfill the uniaxial compressive strength test block 28d, combined slurry slump, bleeding and segregation case. Analysing the tailings-gangue cementitious material gelling mechanism by scanning electron microscopy (SEM) and concluding that mix the tailing, coal, cement and water, hydrate them between each other is a gradual process.A large number of voids and holes will appear in backfill during the gelling process,distributed around the gel product, resulting the complex internal microstructure of backfill.The internal structual of high-strength cemented backfil is much more compact compared to low-strength cemented backfill due to the much hydration products of cement and the pores are occupied in backfill.(2) Using numerical software ABAQUS,"pillar-filling body" combined model was established to analyze the stability of combined model under different width to height ratio-1/5,1/4,1/3,1/2 and 1 respectively. Results showed that the reasonable ratio is 1/3 through comprehensive analysis stress and displacement changes under different aspect ratio. Furthermore, a fitting function relation between vertical displacement y and aspect ratio k of filling body was concluded as followed:When the width-height ratio of "pillar-filling body" combined model is 1/3, the stability of combined model was analyzed as the filling body strength is 1 MPa,3MPa, 5MPa,7MPa and 9MPa respectively. The comprehensive analysis showed that the combined model is in a stable state when the filling body strength is 3MPa, and the stable effect of combined model increase is not obvious as improving the strength of filling body. Further instructions include filling cost, the preliminary optimization filling strength is 3 MPa, following are the fitting function relations:Function relation between themaximum Mises stress y inside the pillar and filling body strength x:Function relation between the maximum Mises stress yon boundary of pillar and filling body and filling body strength x:Function relation between the maximum Mises stress y on pillar upper surface and filling body strength x:Function relation between the maximum Mises stress y inside the pillar and filling body strength x:(3) According to the drilling core data and large core point-loading strength experimental results of No.T26 grouting curtaindrilling,evaluate the ore-rock quality of ZhongGuan stope, obtain that stability level of Zhong Guan iron ore could divided into three levels:unstable, mid-stable and stable.Analyseore block of width 14m、18m、22m、 26m using numerical simulation, compare the ore-rock stress and displacement change according "one-retention-one-mining" or "two-retention-one-mining" (8 combination scheme), get the reasonable width of ore block being 18m, "two-retention-one-mining" mining sequence should be used firstly; and obtain functional relationship between maximum pillar vertical stress、maximum room roof displacement and room width under different mining sequences according numerical simulation results.The functional relationship of maximum pillar stress y and room width x under the condition of "one-retention-one-mining"The functional relationship of maximum vertical room roof displacement y and room width x under the condition of ’one-retention-one-mining"The functional relationship of maximum pillar stress y and room width x under the condition of "two-retention-one-mining"The functional relationship of maximum vertical room roof displacement y and room width x under the condition of "two-retention-one-mining"By analyzingthe pillar stress state of filing stope in afterwards stage, the common failure situation and work state, stopeinstability mechanism is achieved, and summarize that the main factors affecting pillar stress state coming to pillar loading、width height rati、loading time and filling supporting effect.(4) Based on the analysis of mechanical response characteristicsbetween backfill and rock mass,concluded that the effect between backfill body and top mine rock mainly is passive support,restricting the rock in unloaded press circle continue to produce tensile stress and deformation;the effect between backfill body and lateral rock is initiative supporting,restricting the lateral deformation of surrounding rock.After the orebody is mined out,the more promptly filling,the better the control effect on surrouding rock is.Based on the summary analysis of classic design methods onbackfill body strength, author put forward a thinking of dynamic matching design between backfill body and surrounding rock, which is that backfill body both need to satisfy the requirement of self-reliance, as well as withstander of intense mining.(5) Based on the summary of geological and mining conditions ofZhongguan mine, the author analysis the formation mechanism of surface subsidence and rock deformation and destruction process.Through numerical simulation software, predict and analysis the surface subsidence situation caused by filling the empty field subsequent exploitation, obtained the surface deformation parameters. Combined the Design Specifications of Non-ferrous Metal Mining, conclude that surface deformation is inside the allowable range,an could ensure the stability of the surface buildings. Curtain grouting and filling miningare the key to miningunder large water safely for Zhongguan iron mine.