Study on stability of coal pillar in ultra-high water material backfilling mining with different water volume ratios
Taking a certain mine ultra-high water material backfilling mining as the engineering background,the stability conditions of the coal pillar in backfilling working face was analyzed.The internal stress condition,deformation and failure characteristics,and plastic zone development range of the coal pillar under different water volume ratios under ultra-high water filling conditions were studied through numerical simulation methods.The research results indicate that under ideal conditions,to ensure the stability of the coal pillar,the lateral pressure of the filling body on the coal pillar is at least 2.5 MPa.When the water volume ratio of ultra-high water material is less than 95％,the internal stress concentration of the coal pillar is small,the displacement of the coal pillar roof is less,and only plastic zones appear at the edges,without fracture zones,which can maintain the stability of the coal pillar.When the water volume ratio of ul-tra-high water material exceeds 95％,the filling body can still effectively protect the coal pillar,but the internal stress concentration of the coal pillar is large,the displacement of the roof increases,the elastic core area of the coal pillar decreases,and the stability of the coal pillar deteriorates.
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