Study On Stability Of Coal Pillar Front Of The Residual Coal Longwall Working Face

The paper is given priority to with the preservation state of the left-over area and mining conditions in coal seam8of Shenda Group Wangtian Coalmine in Xinzhou city, In the residual coal occurrence mode on the basis of investigation and the on-the-spot investigation and theoretical analysis, numerical simulation methods, in the old mining residual coal district of residue and coal pillar mining face after mining in front of the coal pillar stability was studied, the research contents and conclusions are as follows:1、Looking through the fields, the residual coal mine no.8coal seam mining area coal seam occurrence form structure, the second mining area to choose a mining overall height fully mechanized coal mining methods for recycling.2、By residual coal occurrence mechanics model, residual stress and its stability of coal pillar are analyzed theoretically, calculated by looking out of the field of coal mine residual pillar distance is4m, CanCai zone stability of coal pillar width is4.75m; Spacing is6m, CanCai zone stability of coal pillar width is5.30m; Spacing of8m, CanCai zone stability of coal pillar width is7.25m. Using the cusp catastrophic model in the process of mining are CanCai area of coal pillar stability is analyzed, the results showed that the compound mining face advancing front abutment pressure under the action of limited distance, near the compound mining face side of a small amount of coal pillar damage occurs, the surrounding presents a gradual failure process of coal pillar, won’t cause after a wide range of mining face in front of the roof caving suddenly. In compound mining face advancing front abutment pressure under the action of limited distance near the face side pillar much damage occurs, the surrounding coal pillar in the overlying rock layers (coal) metastatic to occur under the action of a wide range of load instability destruction, compound mining face in front of the roof may be a wide range of sudden collapse.3、Use numerical simulation method, the residue before and after mining coal pillar mining are different spacing width residue yield failure and the vertical stress distribution of coal pillar is analyzed:(1) Before the second mining pillar residue equal spacing, with the increase of width of coal pillar, the pillar proportion of yield failure range with the edge of the vertical stress peak then decreased; Residual pillar width phase at the same time, with the increase of coal pillar spacing, proportion of yield pillar destruction scope with the edge of the vertical stress peak also will increase.(2) Residual pillar spacing is equal, the larger the width of coal pillar, as the compound mining face advancing near the working face coal pillar proportion of yield failure range rather than vertical stress peak value is smaller, the edge of the coal pillar stability is increased; Residual pillar width phase at the same time, the bigger the spacing between the coal pillar, as the compound mining face advancing proportion of yield failure range coal pillar near the working face and the edge of the vertical stress peak value, the greater the stability of coal pillar.(3) the mining coal pillar spacing before is4m, width of5m or more, the distance is6m, width of5m or higher; Spacing is8m, width of7m or higher CanCai zone when the coal pillar in a stable state. After mining pillar distance is4m, width of7m or higher, spacing of6m, width of7m or higher; Spacing of8m, width9m, or more complex mining face in front of the group of coal pillar in a relatively stable state, large area suddenly appeared in front of the roof caving is unlikely.