露天矿端帮开采采硐顶板变形破坏机理

    Deformation and failure mechanism of roadway in open-pit end slope mining

    • 摘要: 为了研究端帮开采中采硐顶板变形破坏机理,建立了两端部固定梁力学模型,结合弹性力学理论,推导出顶板应力、位移计算公式,并考虑支撑煤柱上覆软弱岩层挤压作用对顶板变形的影响,分析得到了顶板应力分布和变形规律。研究表明:顶板的正应力分布呈现二次抛物线轴对称分布,最大拉应力在采硐顶板底面中心位置处最大;最大拉应力和最大剪应力随着开采进度的增大不断增大,顶板底面中部位置先呈现出拉张破坏,随后逐渐转为与煤柱接触位置的剪切破坏;顶板底面的水平位移u值随着x的增大,呈现先减小,再增大,最后再减小的趋势,但侧向挤压对水平位移影响不大;顶板底面的垂直位移ν值随x呈现开口向上的抛物线变化规律,考虑竖向压缩和侧向挤压的位移绝对值|ν|明显大于仅考虑侧向挤压、未考虑侧向挤压的值。

       

      Abstract: In order to study the deformation and failure mechanism of the roof in end slope mining, a mechanical model of the two-end fixed beam was established, combined with the theory of elasticity to derive the calculation equations for the stress and displacement of the roof, and to consider the effect of the extrusion of the overlying weak rock layer of the rib pillar on the deformation of the roof, and finally, the analysis obtained the stress distribution and deformation law of the roof. The research shows that the distribution of normal stresses in the roof is parabolic with a secondary axisymmetric distribution at the center of the roadway, and the maximum tensile stress is at the center of the bottom of the roadway. The maximum tensile stress and the maximum shear stress on the roof increase continuously with the increase of mining progress. The location of the middle of the bottom surface of the roof first shows tensile failure, and then gradually changes to shear failure at the contact location with the coal pillars. The value of u at the bottom of the roof rock beam shows a trend of first decreasing, then increasing, and finally decreasing as x increases, but lateral extrusion has little effect on the horizontal displacement of the roof. The displacement component ν of the roof shows a parabolic variation law with x opening upward. The absolute value of displacement |ν| considering the simultaneous action of vertical compression and lateral extrusion is the most obvious.

       

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