雨水作用下缓倾角岩层露天煤矿凸边坡变形机理研究

    Research on deformation mechanism of gently inclined rock convex slope in open-pit coal mine under the action of rain

    • 摘要: 为了揭示强降雨作用下缓倾角岩层凸边坡剪切滑动破坏机理及其控制措施。本文以宝日希勒露天煤矿边坡为例,采用牛顿力现场监测和FLAC3D三维数值模拟相结合的方法,研究冻融作用下缓倾角岩层凸边坡的内部牛顿力演化规律,分析强降雨作用下无支护和高预应力锚索支护条件下凸边坡的变形规律和塑性区分布特征。研究结果表明:露天煤矿开采形成典型的凸边坡,凸边坡在局部应力集中和卸荷回弹变形共同作用下产生显著变形;在凸边坡解冻期,凸边坡北部边坡产生牛顿力降低,东部边坡产生牛顿力增加;在强降雨作用下,岩体容重增加,边坡内形成裂隙水压力,增加了边坡岩体的滑动力,同时煤层间碳质泥岩强度遇水弱化,形成缓倾角软弱结构面,从而导致边坡岩体沿软弱结构面的整体水平剪切滑动;高预应力锚索可以有效增加缓倾角边坡的整体性,减小由于降雨引起的边坡塑性变形。本文研究工作为后期宝日希勒露天煤矿凸边坡的变形控制和支护设计提供了依据。

       

      Abstract: To reveal the shear creep failure mechanism and control measures of gently inclined rock convex slope under heavy rainfall. In this study, the convex slope of Baorixile open-pit coal mine is taken as an example. The Newton force field monitoring and FLAC3D numerical simulation are used to study the internal Newton force evolution law of the gently inclined rock convex slope under freezing-thawing action, and the deformation law and plastic zone distribution characteristics of the convex slope under the condition of no support and high prestressed anchor cable support under the action of heavy rainfall are analyzed. The results show that typical convex slope is formed in open-pit coal mining, and the convex slope deforms significantly under the combined action of local stress concentration and unloading rebound deformation. During the thawing period of convex slope, the Newton force on the northern slope decreases, while the Newton force on the eastern slope increases. Under the action of heavy rainfall, the bulk density of rock mass increases, resulting in the formation of fissure water pressure in the slope, which increases the sliding power of the rock mass of the slope. Meanwhile, the strength of the carbonaceous mudstone between coal seams is weakened by water, resulting in the formation of a gently inclined structural plane, which leads to the overall horizontal shear sliding of the rock mass along the soft structural plane. The high prestressed anchor cable can effectively increase the integrity of the gently inclined rock slope and reduce the slope plastic deformation caused by rainfall. The research work in this study provides a basis for deformation control and support design of convex slope in Baorixile open-pit coal mine.

       

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