基于刚性块体模型的近−远场崩落矿岩流动特性

Research on near/far-field flow characteristics of caved ore and rock based on rigid block model

为进一步揭示远场条件下金属矿山崩落矿岩运移演化机理,综合利用物理试验、数值模拟和理论分析等手段,构建单口放矿模型开展近−远场崩落矿岩流动特性研究.首次基于离散元软件PFC3D和刚性块体模型构建放矿数值模型,并通过近场放矿物理试验与模拟结果的对比分析,证明了刚性块体模型在崩落矿岩流动特性研究中的可靠性与优越性.在此基础上,对远场条件下松动体形态变化规律、矿岩流动体系内的应力演化规律及其力学机理进行了量化研究.研究结果表明:1)近−远场条件下的松动体形态变化均符合倒置水滴理论.在放矿初始阶段,松动体最大宽度随高度增大呈幂函数形式快速增加;随后,松动体最大宽度随高度增大而近似线性增加.2)崩落矿岩流动过程中存在明显的应力拱效应.随着矿岩散体松动范围不断扩大,松动体外围一定范围内的垂直应力均呈明显下降趋势,水平应力逐渐增大并在松动区域到达前出现激增现象;而松动体内的水平应力与垂直应力则急剧下降至较低水平.

The high mining costs of mines have led to the imbalance between the supply and demand of the total mineral resources in China and the dependence on imports to a large extent.Therefore,it is of great significance to expand the mining scale of mineral resources and reduce the mining costs to improve the self-sufficiency rate of mineral resources and strengthen social support and economic development in China.The caving mining method,especially the block caving method,has the following two main characteristics:one is that caved ores,surrounded by overlying rocks,are drawn from the drawpoint and the other one is that ground pressure is managed by filling goaf with overlying rocks. It is a low-cost and efficient large-scale underground mining method and hasbeen widely used in metal mines around the world. To further reveal the far-field field migration and evolution mechanism of caved oreand rock in metal mine, through physical test, numerical simulation, and theoretical analysis, isolated-drawpoint draw models wereconstructed to study the flow characteristics of near/far-field flow characteristics of caved ore and rock. Based on the discrete elementsoftware PFC3D and rigid block model, the numerical draw model was constructed for the first time. The reliability and superiority of therigid block model in the study of flow characteristics of caved ore and rock were proved by comparative analysis between near-fieldphysical draw test results and simulated results. Moreover, the variation law of the IMZ (Isolated Movement Zone), the stress evolutionlaw and its mechanical mechanism in the particle flow system under far-field conditions were quantitatively studied. The key researchresults prove that: 1) The shapes of IMZ under near/far-field conditions conform to the upside-down drop shape theory. In the initialdraw stage, the maximum width of IMZ increases rapidly with the increase of height in the form of power function;while in thefollowing draw stage, the maximum width of IMZ increases almost linearly with the height increase. 2) There is an obvious stress archeffect during the flow of caved ore and rock. With the range expansion of the caved ore and rock, the vertical stress in a certain rangeoutside the IMZ decreases obviously, while the horizontal stress gradually increases and surges before the arrival of IMZ. Furthermore,the horizontal and vertical stresses within the IMZ drop sharply to a lower level.