露天矿排土场软岩重塑阻水机理与边坡稳定性精准评价

With a long term heap load in waste dump slope of open pit mine, the soft rock granular material will come out a remodeling phenomenon, and its microscopic structure change will cause the mechanical strength change, the water-stagnated and capillary effect coordinately, which has an important influence on waste dump slope stability. It is lack of effective experimental method and analysis theory for mechanical strength, hydraulics index and slope stability development regularity of soft rock waste dump in heap load process. The project will research on the remodeling and water-stagnated mechanism of soft rock in waste dump with the use of experimental method, theoretical analysis and numerical simulation comprehensively. The comprehensive strength of complex rock mass in waste dump slope and water head height of seepage redistribution can be measured accurately by the patent technology equipment of in-situ and seepage experiments. The analysis method for water pressure during seepage process put forward based on the Bernoulli's theorem, will reveal the water pressure distribution law in different areas of the waste dump. According to the remodeling characteristics and heap load pressure of different soft rock seam, the methods of partition and parameter assignment for each rock seam in waste dump slope would be put forward, and the method of superposing capillary and gravity water head height to determine the saturation line height would be established too. At last the numerical analysis model for waste dump slope stability would be established, which will lay a foundation for the time-dependent stability evaluation and structure optimization of waste dump slope in stacking process.

软岩散体物料在露天矿排土场长期堆载会产生重塑效应，其细观结构变化造成的力学强度改变和阻水、毛细效应对排土场内部力学结构和边坡稳定性具有重要影响。软岩堆载过程中的力学强度、水力学指标及边坡稳定性发展规律，尚缺少有效的实验方法和分析理论。本项目拟综合运用实验研究、理论分析和数值模拟开展排土场软岩重塑及胶结阻水效应研究。采用原位实验和渗流实验专利技术及设备实现对排土场复杂岩体综合抗剪强度和渗流水头高度的准确测定，基于伯努利定理提出的“变径”渗流水压力分析方法，揭示排土场不同区域的水压力分布规律。基于软岩的重塑特性和不同层位的堆载压力，提出排土场岩体分层及参数赋值方法，以及重力水头及毛细水头高度叠加确定浸润线高度的方法，并据此建立排土场稳定性数值分析模型，为排土场堆载过程中的时效稳定性评价和结构优化奠定基础。

软岩剥离物在排土场堆载重塑过程中，其细观结构变化造成的物理力学及水理性质变化对排土场边坡变形失稳产生重要影响。根据排土场散体物料重塑强度的影响因素，推导了散体重塑沉降量计算模型，建立了重塑岩体抗剪强度的表达式，揭示了散体物料在重塑过程中抗剪强度随平均孔隙比的降低呈线性增长；设计了分级加载、连续加载重塑固结实验方案、重塑岩体的渗流实验方案及露天矿排土场原位实验方案。.根据固结重塑实验结果，得到了重塑岩体的压缩系数、压缩模量的变化规律，证明了散体软岩属于高压缩性土；揭示了重塑岩样的密度随重塑压力增加呈指数规律增长；孔隙比随密度的增长呈负指数规律变化，试样含水率随密度的增长呈线性规律下降。.室内试验结果表明黏土重塑过程中的黏聚力随着重塑压力的增大呈二次函数增长，而内摩擦角与重塑压力未表现出明显的相关性。砂土的黏聚力和内摩擦角较为稳定，均不受重塑压力的影响。散体物料重塑强度与重塑时间的相关性不强，胜利露天矿排土场原位实验结果验证了这一规律的正确性。.将不断变化的动、静水压力进行量化建模，纳入到边坡稳定性分析，并推导出考虑水压力的稳定系数计算公式。基于排土场临空面的板结滞水特性，建立了原始渗流和板结滞水条件下的地下水渗流模型。采用数值模拟研究了临空面板结滞水、基底胶结隔水、重塑岩体各向异性等因素对于排土场边坡稳定性的影响规律。揭示了排土场边坡稳定性随板结滞水层厚度增大、基底隔水层位置提高呈线性下降；随各项异性系数的增加呈指数规律增加的基本规律。.根据排土场力学结构，给出了自锁及解锁状态的判别准则，改变煤层底板的摩擦系数，可以使排土场处于“自锁”或“解锁”状态。降低排土场边坡角、降低排土场基底倾角、煤层底板粗糙化处理，都可以实现排土场基底由“解锁”到“自锁”状态的转变。.基于排土场的作业程序和不同层位土石混合体力学强度的分布规律，分别进行了多层平行推进排土和逐层排土这两种方案的边坡稳定性评价，得到了动态排土过程中的稳定性变化规律，为排土场作业方案和结构优化的依据。