Granule structure influences on force chain development in the slag medium
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摘要:
矿业活动产生的渣体是不规则颗粒介质, 具有级配复杂、结构不稳定的特征, 颗粒间通过力链传递应力。以典型铜矿渣为研究对象, 借助CT扫描技术获得矿渣的颗粒结构形态, 通过开展不同粗颗粒含量的平面压缩试验和数值模拟试验, 得到宏观力学变形曲线及力链发展过程和颗粒结构变化, 讨论颗粒结构和力链发展协同作用对宏观力学性质的影响机制, 以及颗粒介质材料压缩发展规律。结果表明: 矿渣类颗粒介质材料的力链发展方向与压力方向一致; 矿渣宏观抗压性能随>5 mm粗颗粒含量的增加先增后减, 在最优粗细颗粒配比50%处达到最大抗压强度; 颗粒结构和力链间软硬结构存在显著的协同演化; 压缩过程中内部存在快速压密、颗粒破碎和稳定压缩3个阶段。在矿渣堆填过程中, 除控制其粗颗粒在最优级配外, 保持均匀填筑和合理的压实使其进入稳定压缩阶段也非常重要。
Abstract:The slag dumps formed by mining activities are irregular granular media. Their particle size gradations are complex and granule structures are unstable.The stress between particles is transferred through the dependently unstable force chain. Taking the typical copper slag as the study object, its granule structure was investigated using CT scanning technology. According to plane compression and corresponding numerical simulation tests on coarse particles of different mass fraction contents, stress-straincurves, force chain evolutions and granule structure changes were obtained.Further, the synergistic effect between granule structure and force chain evolutionon macro-mechanics was discussed. Meanwhile, the compression law of granular material was revealed. The results show that the direction of force chain evolution direction inslag granular materialis consistent with the direction of pressure. The macro-compressive strength of slag increases first and then decreases with increasing coarse particle (>5 mm) mass fraction content and reaches the maximum compressive strength at the optimal coarse particle ratio of 50%. The granule structure and the soft-hard structure inforce chains have a significant synergistic effect. The granule structure change in slag granular material will experience three stages during compression process: the rapid compaction stage, particle crushing stage and stable compression stage. In the process of slag landfill, it is important to keep uniform filling and reasonable compaction to make it enter the stable compression stage, as well as controlling the optimal grading of coarse particles.
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Key words:
- slag /
- granular material /
- granule structure /
- force chain /
- plane compression test
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表 1 铜矿渣的级配参数表
Table 1. Gradation parameter of copper slag
名称 d10/mm d30/mm d60/mm Cu=d60/d10 Cc=d302/(d10d60) 平均粒径d50/mm 粗颗粒w5/% 铜矿渣颗粒级配 0.47 1.27 3.84 8.17 0.89 2.98 30.15 注:定义粒径>5 mm的颗粒为粗颗粒,粗颗粒质量分数用w5表示;d10为小于该粒径的土颗粒的质量占土颗粒总质量的10%,也称有效粒径;d30为小于该粒径的土颗粒的质量占土颗粒总质量的30%,也称连续粒径;d60为小于该粒径的土颗粒的质量占土颗粒总质量的60%,也称控制粒径 表 2 铜矿渣6组优势外形轮廓几何参数统计表
Table 2. Statistical table of geometric parameters of six groups of dominant profiles of copper slags
分类 1 2 3 4 5 6 优势外轮廓 球形度S 0.29 0.60 0.65 0.52 0.69 0.33 长宽比F 5.96 3.31 3.16 3.85 3.63 5.62 圆形度R 1.22 1.10 1.02 1.07 1.08 1.05 表 3 铜矿渣大型压缩试验参数反演标定
Table 3. Parameter inversion calibration table for the large-scale compression test of copper slag
参数类型 标定值 颗粒密度ρ/(kg·m-3) 2 608 接触颗粒间弹性模量Ec/Pa 2×107 法向切向刚度比k 1.05 接触摩擦系数μ 0.3 平行黏结弹性模量Ep/Pa 6.5×107 平行黏结刚度比kp 1.05 平行黏结抗拉强度σc/Pa 0.9×107 平行黏结内聚力c/Pa 4.5×107 -
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