Research On Strength Of Full Tailings Cemented Mining Of "Three Under Mining"

The safety mining of "three under mining " of ore bodies is always an importanttask of mining aera and industry, filling mining method becomes unique because of itsspecial advantages, and it played great importance and constantly developed in threeunder mining mine, but, generally, research on the strength of the filling body onlystay in the filling material tests, and the strength of the filling body and stope stability,surface subsidence and other related research are not so much.This paper takes Henan Yangjiawan iron-zinc mine mining engineering phase IIas the researching background. The mine is regarded as the typical three undermining mine, the ore body lies under road and river, and the surrounding rockstability is very poor.The former mining activity had caused3subsidences on theground at the end of2012. It is about42m from the road of west mining site to themoving boundary. If sublevel caving method is continue to be used, the movement ofsurface rock scope will be further expanded, and ultimately result in the destruction ofhighway and river nearby. Therefore, in order to solve problems of subsidences ofmining under road and river, considering to adopt full tailings cement filling methodto mine, and study the mechanism of backfill into the mined out area, the mechanicalproperties of backfill surrounding rock with stability, then calculate the groundsurface subsidences. The main contents are as follows:At first， collecting of full tailings and conducting full tailings materialexperiment. According to the result of the tailing material experiment，the strength ofthe filling body formation mechanism, mechanical parameters and filling slurryrheological and transport properties are concluded, which provide the basic data forthe following numerical simulation. And experiment result could conduct backfillingsystem design and construction and guide mining technique to carry out smoothly.According to the mine site present situation of mining and geological conditions,selection of the fuzzy mathematics comprehensive evaluation method which couldmake various fuzzy factors quantitative and numerical. Then utilize comprehensiveevaluation method to weigh advantages of4kinds of mining method in technical,economic, security and other aspects, then recommend upward drift stoping withbackfill method as the main mining method which could ensure the reliability andadvancement of the chosen method. The sequence of this kind of mining method is from the under layers to the top layers, each layer is divided into a number of routes,each route as a mining stope, backfill should be done as soon as mine is over. Thelevel height is50m, divided into5segments, each segment height is10m, stope (route)length is40m~50m, route size is3.0m×3.0m. The mining method can easily adapt tothose poor stability ore rock, and ensure the operation safely, and at the sametimereduce the mining dilution and loss rate, which could improve the comprehensiveeconomic benefit.First to apply calculational analysis and FLAC3Dnumerical simulation toanalysis the strength of filling body of three under mining，which quantitativelyanalysis how to maintain the stability of stope and how much settlement the groundwill be, which break the limitation of traditional empiricism. First to simulate fillingof different intensity’s mechanism when excavate filling process of stope andsurrounding rock stress and displacement function, from the research it can beconclude that the strength of the filling body up to above0.6MPa can play asupporting role to ensure the stability of stope and surrounding rock. Then basic onthe "Code for design on nonferrons metal mining" of chapters of9.24,9.25, in whichdetailedly provide ground deformation and allowable pramater for standard of "threeunder mining", conducting surface recording method by calculation and analysis ofdeformation, research on the different strength of backfill settlement on the ground.Combined the filling body strength result of the filling materials experiment withcement-sand ratio and slurry concentration curve, and conclude that when the strengthof filling body is more than or equal to0.9MPa, it can meet the protection of surfacedeformation requirements of the road and the river. PC32.5cement as cementitiousmaterial can meet the safety mining, while ensuring the slurry concentration ofsurface rivers and roads without destroying is72%, cement-sand ratio is1:4.In this paper, combined with the filling material experiment, fuzzy mathematics,calculation and analysis and numerical simulation software FLAC3Dto analysis andresearch on what kind of filling mining method is suitable for the mine, in the endconclude the appropriate strength of the filling body for mining, which further enrichthe research strength of filling method and provide theoretical support for the safeproduction in mines, relieve the surface subsidences, protect the mine ecologicalenvironment, it is of great significance to the sustainable development of mine.