The First Phase Of Horse Iron Mine Goaf Stability Study

There may be many mined-out areas left due to underground mining of deposits, and it can threat the safe production of mines and normal life of surrounding residents if not treated in time. Mined-out areas should be treated scientifically on the basis of analyzing the stability. Taking some untreated mined-out areas of Makeng Iron first-phase project for research object and on the basis of collecting and consulting the related information, the stability of mined-out areas was comprehensively analyzed by similar material simulation and FLAC3D numerical simulation, and the processing method was proposed. The research contents are as follows.(1) Collecting and collating information about mined-out areas, analyzing distribution, geometric parameters and spatial pattern of the mined-out area groups left by the first-phase project, and determining the rock mechanics parameters by the means of weakening them.(2) In order to ensure the accuracy of simulation experiments, conducting the laboratory experiments of simulating material ratio and obtaining simulating material ratio, with the ratio of ore-body573#and that of surrounding rock673#.(3) In order to study the stability of mined-out areas under gravity left by the first-phase project and the effects of lower ore-body mining on upper stability, simulating materials experiments were conducted. It is shown that tension forces of upper ore-body roof increase due to lower mining, roofs down and baseboards up phenomenon is obvious. The stability grade of mined-out areas is Ⅳ after the middle of390is mined through stability grade standards.(4) Establishing3D model of mined-out areas by using finite difference procedure FLAC3D. The stability grade of mined-out areas is determined Ⅳ through comprehensive analysis of Plastic zone distribution and danger coefficient. Some disciplines can be obtained by studying the distribution regularity and vertical displacement of maximum principal force and shearing force, such as tension forces of upper ore-body roof increasing due to lower mining, shearing force of pillars increasing.(5) It is shown from the analysis results of similar material simulation and numerical simulation that mined-out areas are in serious instability in the middle of390left by first-phase project of Makeng Iron. Roof tensile-failure and pillars shear-failure is the instability pattern. The earth’s surface around Taibaolin may collapse and should be tested periodically.lt is an effective method to comprehensive analyze stability of mined-out areas of Makeng Iron by using similar material simulation and numerical simulation(6) According to the results of analysis stability of mined-out areas and actual situation of mining areas, using combined method deal with the mined-out areas.