Discrete element modelling on dynamic triggering mechanism of the Pusa landslide in Nayong county, Guizhou Province
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摘要: 采用UDEC离散单元法数值模拟,再现了贵州纳雍张家湾镇普洒滑坡在煤层采空区、深大岩溶裂隙、强降雨和回采爆破振动协同作用下的动力响应特征,揭示出该崩滑的动力触发机制与主控因素。结果表明:(1)在原始坡体下伏煤层自下而上依次开采时,其采空区上覆岩层中“冒落带”、“裂缝带”和“弯曲下沉带”范围逐渐扩大,当位于最上部的煤层被开采后,其上覆岩层中发育的“弯曲下沉带”已触及坡脚;期间该原始坡体处于累积变形阶段,其变形具有明显的整体“下座”和“顺时针旋转”特征;(2)在强降雨作用时,已受采空区作用的坡体进入累积变形扩大阶段,其宏观变形仍具有“下座”和“顺时针旋转”特征;(3)当回采爆破振动持续作用时,已受采空区和强降雨耦合作用的变形坡体进入持续“渐进损伤”、“临界崩滑”、“解体破碎”、“震荡抛射”和“堆积压实”动力响应阶段,期间滑坡体宏观位移表现出明显的“下座”、“溃屈”和“顺时针旋转”特征。Abstract: This paper presents a discrete element modeling using UDEC software to reproduce the dynamic response of the Pusa landslide triggered by the combination of goafs, deep major karst cracks, heavy rainfall and continual blasts during underground coal mining. Based on the reproduction, the dynamic triggering mechanism and the key contributing factors of the landslide are analyzed. The results show that caving, crack and deformation zones that developed in the strata overlying goafs during mining coal seams expand up gradually below the slope. The deformation zone meets the toe of the original slope after mining of the uppermost coal seam. Meanwhile, an obvious progressive deformation zone develops in the original slope containing the deep karst fractures. The deformation behaves as a wholly downward and clockwise movement. On the condition of the heavy rainfall, a continuous progressive deformation zone develops in the slope that has been influenced by the goafs. The deformation continues to behave more downward and clockwise movement as a whole. Finally, while the continual stope blasts, as the key contributing factor for the landslide, during the underground coal mining, the slope that has been influenced by the goafs and the heavy rainfall enters multiple-phase dynamic response stages including further progressive damage deformation, critical collapse, shattering, ejecting and compaction. Simultaneously, the whole slope exhibits a downward, apart break and clockwise rotation. These results modeling would provide a support for control of similar landslides.
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Key words:
- the Pusa landslide /
- dynamic triggering mechanism /
- discrete element modeling /
- goaf /
- heavy rainfall /
- stope blasting
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