急倾斜矿体空场法开采的矿柱回收与卸压开采效果数值分析

矿柱回采方法不恰当,将致使大量矿柱残留采场而无法经济、安全地回收。为了解决上述问题,避免或消除深部开采产生的地压灾害,提出了间隔矿柱抽采法回采间柱,"V"型松动爆破并上盘底板松动爆破隔断开采,采用FLAC3D数值模拟了矿柱回采及深部卸压开采的应力变化过程,将数值模拟结果与实际开挖进行了对比,并在此基础上评价了矿柱回收及卸压开采的效果。结果表明:间隔抽采矿柱后,1 010 m中段第一分层顶柱及其以下保留的矿柱不会发生冒落,但上盘局部千枚岩会因长期拉伸疲劳破坏而垮塌,为了避免采空区顶板长期暴露、垮落而造成出矿贫化,必须加快出矿;"V"型松动爆破并上盘底板松动爆破隔断开采,降低了910 m中段开采的应力集中程度,基本消除了910 m中段开采时发生岩爆的应力条件;回收过矿柱的相邻采空区的分隔间柱,其回采宽度不应超过1/2;相邻两采空区都间隔抽采间柱并卸压开采后,960 m中段基本实现了垮塌的千枚岩或残留矿柱充填采空区,从而消除了采空区隐患。

3-D simulation analysis for the pillar and pressure relief effects in the empty field sharp-inclining mining structure

The given paper is aimed to simulate the recovery of pillars,the goaf-processing and deep-pressure relief mining practice with large numbers of residual pillars being unable to be economically and securely recovered short of proper methods for such mining.To simulate the recovery of such deep-relief mining process,we would like to propose a novel method in given paper.The said novel method in our mind is to adopt the separation pillar extraction to recycle the rib pillars by way of V-shaped loosening blast and the partition mining on the hanging tunnel bottom plate so as to get rid of and even totally relieve of the ground pressure disaster risks in the deep-layer underground mining.In so-doing,we have simulated the stress changing process by FLAG3D,which is generally thought to be in accord with the actual demands of such mining as a result of careful evaluation of the effect of the pillar recovery and deep pressure relief mining method.The results of our study demonstrate that the first layer of the pillars and those below the 1 010 m level wouldn' t get collapsed and the phyllite on the hanging wall may merely get to collapse locally due to the prolonging fatigue damage in the pillar separation and extraction process.Furthermore,it would be possible to get rid of the mining ore depletion by the prolonging exposure and caving on the roof of the goaf by speeding up the mining process.On the other hand,the V-shaped loosening blast and the partition mining on the bottom plate of the hanging tunnel can just psrtly reduce the stress degree at the 910 m level,which helps to eliminate the stress condition of the rock burst basically at the level of 910 m.Nevertheless,the separating rib pillar recycle between the two adjacent goaf areas,the pillar extraction should not be beyond half of the total.And,when the extended separation pillar and the pressure relief mining process going on to the two adjacent goafs at the 960 m level have been filled with the cracked phyllite on the hanging wall with residual pillars in the stope favorable to get rid of the hidden risk.Thus,it can be seen that the conclusion we have made well in accord with the mining practice,which can thus provide a basis for recovering the residual pillars economically and securely in the similar mining work.