Cui Bo, Bi Yuanlong, Gu Tianfeng, Han Kai
State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi'an, 710069, China.
Sci Rep. 2024 Oct 11;14(1):23847. doi: 10.1038/s41598-024-75255-x.
Particle shape is an important factor affecting the strength and deformation of coarse materials in dumps. However, conducting research on particle shape in current laboratory experiments, and there exists no classification standard for the particle shape of the dump. Considering the project on high-bench dump in Jiangxi Province, based on the random particle construction method, this study determined the characteristic particles of coarse grain material in the dumping site by combining field investigation results, large-scale direct shear tests, and numerical analysis. Further, the influence mechanism of coarse grain content and characteristic particles on the mechanical characteristics of the dump were analyzed. The results showed that the increase in coarse grain content enhanced the irregularity of particle shape, increased the internal friction angle between particles, and reduced the cohesion of the dump. Moreover, with increase in the normal stress, the shear strength changed from insignificant to gradually enhanced, although the increasing trend slowed down. The constructed random particle model can well solve the effects of occlusion, nesting, and friction between particles that is neglected by the standard spherical particle model, and the fitting degree is better. The particle characteristics of coarse-grain materials in the dump were primarily block, strip, and flake. The three types of shape characteristics under low normal stress did not affect the mechanical properties of the dump. Further, with the increase in normal stress, the stress-strain curve reflected the shape characteristics and content of the dominant characteristics in the dump. Specifically, the block sample exhibited the dominant characteristics and the most content under the same normal stress, followed by the strip sample, with the flake sample exerting the least influence. The research results provide a theoretical basis for long-term safe operation, disaster monitoring, and early warning of high bench dump.
颗粒形状是影响排土场粗粒料强度和变形的重要因素。然而，目前在实验室试验中对颗粒形状进行研究时，排土场颗粒形状尚无分类标准。结合江西省高台阶排土场工程，基于随机颗粒构建方法，本研究通过现场调查结果、大型直剪试验和数值分析相结合的方式，确定了排土场粗粒料的特征颗粒。进而分析了粗粒含量和特征颗粒对排土场力学特性的影响机制。结果表明，粗粒含量增加会增强颗粒形状的不规则性，增大颗粒间内摩擦角，降低排土场的黏聚力。此外，随着法向应力的增加，抗剪强度从无显著变化逐渐增强，但增长趋势减缓。所构建的随机颗粒模型能够很好地解决标准球形颗粒模型所忽略的颗粒间咬合、嵌套及摩擦等影响，拟合度较好。排土场粗粒料的颗粒特征主要为块状、条状和片状。低法向应力下这三种形状特征对排土场力学性质无影响。进一步地，随着法向应力增加，应力 - 应变曲线反映了排土场中主导特征颗粒的形状特征和含量。具体而言，在相同法向应力下，块状颗粒样本呈现主导特征且含量最多，其次是条状样本，片状样本影响最小。研究结果为高台阶排土场的长期安全运行、灾害监测与预警提供了理论依据。
