软弱基底内排土场支挡煤柱的力学效应

留设支档煤柱是提高软弱基底内排土场稳定性的重要手段之一。为了解决软弱基底内排土场支挡煤柱形态参数设计难题,实现矿山安全生产和经济效益兼顾,对软弱基底内排土场支挡煤柱的力学效应及形态设计方法进行研究。在构建软弱基底内排土场支挡煤柱力学模型的基础上,进行三维受力状态分析,将支挡煤柱视为在内排土场静止土压力及底界面剪切力双重作用下的固定梁,以摩尔-库伦准则作为失稳判据,推导获得了煤柱三维支挡效应的表达式;基于对煤柱三维支挡效应的力学成因类型及影响因素的认识,提出了煤柱支挡效应的二维等效方法,推导了底界面等效黏聚力c_d与等效内摩擦角φ_d的表达式,从理论上揭示了支挡煤柱形态参数对支挡效应的影响。将该方法在胜利东二露天煤矿内排土场支档煤柱设计中进行了应用,并采用数值模拟方法进行验证。研究结果表明:煤柱底界面的等效黏聚力c_d及等效内摩擦系数tan φ_d与其顶宽a、下底角β,ω均呈正相关反比例函数关系,与高度H呈正相关倒差函数关系,与长度d呈负相关反比例函数关系;胜利东二露天煤矿内排土场边坡稳定系数F_s随支档煤柱顶宽a增加而增加,与煤柱高度H呈线性递增关系;煤柱的最佳尺寸为高度H=28 m,顶宽a=43 m,与传统的二维分析结果相比,可多才出原煤75 600 m^3,经济效益显著。成果可用于优化设计软弱基底内排土场支挡煤柱形态参数,弥补采用传统方法设计造成的煤炭损失过大的不足,实现经济效益最大化。

Mechanical effect of supporting and retaining coal pillar on internal waste dump with weak basement

Supporting and retaining coal pillar is one of the important means to improve the stability of internal waste dump with weak basement.To solve the problem of designing morphological parameters of supporting and retaining coal pillar on internal waste dump with weak basement,and to achieve the safe production and economic benefits of the mine,the mechanical effects and shape design methods were studied.Based on the mechanical model,the three-dimensional force state analysis was carried out.The supporting and retaining coal pillar was regarded as a fixed beam under the dual action of the static earth pressure of internal waste dump and the shear force at the bottom interface.The Mohr-Coulomb criterion was used as the instability criterion,authors derived the expression of three-dimensional supporting and retaining effect of coal pillar.Based on the type of mechanical genesis and influencing factors,a two-dimensional equivalent method for the supporting and retaining effect of coal pillars was proposed and the expression of cd and φd were derived.In theory,the influence law of morphological parameters on the supporting and retaining effect was revealed.The method was verified by numerical simulation  the internal dump  Shengli East No.2 open-pit mine.The results showed that cd and φd are positively inversely proportional to their top width a and lower bottom angles β and ω, positive correlat with the height H,and negative correlat with the length d The stability coefficient Fs of the internal dump of Shengli East No.2 open-pit mine increases with the increase of a,and increases linearly with H The optimal size of the coal pillar is 28 m and 43 m.Compared with the traditional two-dimensional analysis results,more than 75 600 m3 of raw coal can be produced,and the economic benefit is remarkable.The achievement optimizes the morphological parameters of supporting and retaining coal pillar to make up for the inadequacy of excessive coal losses caused by the traditional and to achieves a maximum economic benefit in mining operation.