深部松软煤层钻孔孔周煤体变形产渣特征研究

针对煤矿井下高瓦斯软煤顺层长钻孔排渣困难、成孔率低、施工困难等问题,通过数值模拟实验研究了井下深部软煤体变形破坏特征,分析了顺层长钻孔孔周松软煤体变形特征及应力变化,以揭示顺层长钻孔孔周松软煤体变形产渣规律。研究表明:深部高瓦斯软煤顺层钻孔孔周煤体的应力平衡临界条件破坏后将发生大体积突然垮落;钻孔水平最大变形位移为1.22mm,垂直方向最大变形位移为10.7mm;径向孔周煤体垂向变形呈现逐渐减小趋势,且垂向变形明显大于钻孔水平变形。在水平方向上,钻孔孔周煤体应力分布呈现先增大再逐渐减小的变化规律,径向距离对水平应力分布的影响逐渐减小;随着径向距离的增加,钻孔孔周煤体应力分布逐渐降低,钻孔孔壁处煤体的应力出现最大值,且垂直方向处应力值最大。

Numerical Simulation Study on Slag-producing Regularity of Coal Body around Borehole in Deep Soft Coal Seam

In this paper, the difficulty of slag discharge and the low porosity of the high-gas soft coal in the underground coal mine are studied. The numerical simulation of the deformation and slag production of deep high gas soft coal under the combined stress is carried out by FLAC3D numerical simulation technology. The law of slag generation and deformation of deep high gas soft coal in the bedding layer is revealed, and the deformation characteristics and stress variation of the coal around the long hole in the bedding layer are analyzed. The numerical simulation study shows that the large-volume sudden collapse will occur after the critical condition of the stress balance of the coal body in the deep high gas soft coal bedding hole; the maximum deformation displacement of the drilling level is 1.22mm, and the maximum deformation displacement in the vertical direction is 10.7mm; along the radial distribution of the borehole, the vertical deformation of the coal around the hole shows a decreasing trend, and the vertical deformation is significantly larger than the horizontal deformation of the borehole. In the horizontal direction, the stress distribution of the coal body around the borehole increases first and then gradually decreases. The influence of the radial distance on the horizontal stress distribution gradually decreases. With the increase of the radial distance, the borehole The stress distribution of the coal body gradually decreases, the stress of the coal body at the wall of the borehole appears the maximum, and the stress value in the vertical direction is the largest.