干堆排尾对露天坑坑下采场稳定性的影响

Influence on underground mining stability of stope during stacking dry stacked Gangue in open-pit

针对铜绿山露天转地下矿山利用露天坑干堆尾砂技术,采用FLAC3D数值软件,运用强度折减法及拟合函数位移突变特征法,对露天坑尾砂堆积过程进行破坏判定及稳定性安全系数求解,从而分析露天坑排尾的可行性。研究结果表明:当尾砂堆高h=0 m时,最优境界顶柱高度H=20 m,可允许的采场跨度D>34 m,主要破坏形式是空区顶板两端剪切破坏;当h>0 m和D>30 m时,采场有垮塌现象,露天坑台阶塑性区明显;当h>160 m时,空区塑性区面积及顶板位移迅速增大,堆积对空区的破坏程度大为增加,采场的合理跨度进一步减小。

In view of Tong-lü-shan underground mining shifted from open-pit using dry stacked Gangue technology,the numerical simulation software combined with the strength reduced methods and the displacement mutation characteristics of monitoring points was used to analyze failure features of goaf and stability safety coefficient under different heights of dry gangue.Feasibility analysis about stacking gangue was done.The results show that when there is no tailing loaded,the optimal thickness of boundary pillar is20m and the allowed spans are more than34m.The form of goaf failure is that both ends of roof are shear failure;When it begins to load tailings and the span is more than30m,the stope collapse and the area of rock’s plastic deformation is obvious;When the tailing loaded exceeds160m,the area of stope’s plastic zone and roof displacement rapidly increase,and the stacking gangue to the extent of goaf damage also increases considerably,which may further reduces the reasonable span of the stope.