Study On The Reasonable Size Of Shaft Protective Coal Pillar Based On Solid Backfill Mining

With over exploitation of the coal resources and decreasing of recoverable reserves of the mines in themiddle east of china, mine enters the stage of residual mining, protective coal pillar of industrial square is of high value in this stage. When mining coal pillar, in order to ensure the normal operation of the mine production system, shaft protection coal pillar need to stay a certain range to ensure wellbore from mining damage.In this paper, aiming at the problem of setting shaft protection coal pillar during the solid filling mining protection pillar of industrial square, I study on the model of shaft protection coal pillar set with three models, the method of retention of shaft coal pillar based on solid backfill is proposed. Firstly, this paper has analyzed the factors that affect the deformation and damage of the shaft, the main control factors which affect the deformation and damage of shaft are obtained; Secondly, the deformation and damage law of shaft coal pillar under the condition of different influence factors was studied by theoretical analysis, numerical simulation, regression analysis and probability integral method, we get the estimated formula of maximum axial stress of shat based on solid backfill. The model of retention of shaft coal pillar based on theoretical analysis and on the numerical simulation were put forward respectively. Comprehensive above all kinds of model of retention of shaft coal pillar, the method of retention of shaft coal pillar based on solid backfill is proposed. Finally, in case of Baishan coal mine, a shaft protection coal pillar was set up, on the basis of this, the design of the filling mining plan of protected coal pillar area of industrial square is designed. Through the probability integral method, the displacement and strain of industry squre and shaft were predicted. The main achievements are as follows:(1) Through the summary of the existing literature, the influence factors of shaft deformation has been studied. The main controlling factors for the shaft deformation and damage with solid backfill mining are filling rate and the exploitation range. Ensure shaft stability, Control the maximum axial stress of the shaft is the key to design the retention of shaft coal pillar, shaft deformation failure criterion is s() ￡[s]cz.(2) Aiming at the problem of setting shaft protection coal pillar during the solid filling mining protection pillar of industrial square, with the introducing of the theory "The equivalent mining height model" and the applying of Gauss’ s influence function method, the relationship between shaft deformation and "the filling rate and the radius of protective coal pillar" are calculated, the formula for predicting the maximum axial stress is obtained, the model of retention of shaft coal pillar based on theoretical analysis is proposed.(3) Using Abaqus, the three-dimensional finite element numerical analysis software, the deformation and damage law of shaft coal pillar during backfill mining is studied: The maximum axial strain was negatively correlated with the filling ratio, when the radius of the shaft protection coal pillar is 132 m, the reasonable filling rate shall not be less than 80%; negatively correlated with the exploitation range, when the filling ratio is 80%, the reasonable shaft protection coal pillar should be more than 132 m. According to results of numerical simulation, the estimated formula of the maximum axial strain with backfill mining is obtained by regression analysis, the model of retention of shaft coal pillar based on the numerical simulation is proposed.(4) Integrated three kinds of model of shaft protection coal pillar set, respectively based on vertical section method、theoretical analysis、numerical simulation, the method of retention of shaft coal pillar based on solid backfill is proposed. In case of Baishan coal mine, a shaft protection coal pillar was set up, on the basis of this, the design of the filling mining plan of protected coal pillar area of industrial square is designed. Using surfer map analysis software draw the control index of the filling rate of the coal pillar of industrial square, the current regional full rate in the production process shall not be lower than that of the index. The mining face layout of industrial square area in experimental mine is finished, and surface subsidence and the shaft damage deformation are predicted by probability integral method. The relationship between the maximum axial deformation of the shaft, the filling ratio and the mining area is verified.