Abstract Optimum fragmentation of rocks during blasting is pivotal for the productivity of mining and civil engineering systems. Extensive studies on the ubiquitous fragmentation phenomena in nature and artificial processes have attested to the dominant control of the effective dimensionality and material brittleness on the size distribution of fragments. In this study, by further demonstrating that the impact of brittleness on fragmentation is physically inherent in the material dimension, we present new mechanistic insights into the blast-induced rock fragmentation via integrated analytical modelling, finite element simulation and image processing. A continuous-surface viscoplastic cap model was first calibrated step-by-step against rock behavior in different pressure and strain-rate regimes on various scales. Then, rock blasting was simulated under various bench dimensions and the fracture patterns were image-processed to provide quantitative insights into blast fragmentation. Our findings suggest that the fragments become smaller and rounder while their size distribution becomes more uniform as the rock dimensions decrease. We demonstrated that at smaller rock dimensions, the equivalent increase in energy density and suppression of pressure-induced ductility can conspire to assist crack bifurcation and thus create successively finer fragments towards the unbreakable limit. We also identified significant correlations between the fragment aspect ratio and its size and uniformity of distribution, highlighting the potential use of fragment shape as an indicator for evaluating blasting performance alongside conventional grading analysis.

中文翻译：

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爆破岩石破碎的数值研究

摘要 爆破过程中岩石的最佳破碎对采矿和土木工程系统的生产力至关重要。对自然界和人工过程中普遍存在的破碎现象的广泛研究已经证明，有效维数和材料脆性对碎片尺寸分布的主导控制。在这项研究中，通过进一步证明脆性对碎裂的影响是物理固有的材料尺寸，我们通过综合分析建模、有限元模拟和图像处理，对爆炸引起的岩石碎裂提出了新的机械见解。连续表面粘塑性顶盖模型首先针对不同尺度下不同压力和应变率状态下的岩石行为进行了逐步校准。然后，在各种平台尺寸下模拟岩石爆破，并对断裂模式进行图像处理，以提供对爆破碎裂的定量见解。我们的研究结果表明，随着岩石尺寸的减小，碎片变得更小、更圆，而它们的尺寸分布变得更加均匀。我们证明，在较小的岩石尺寸上，能量密度的等效增加和压力引起的延展性的抑制可以共同促进裂缝分叉，从而不断地产生更细的碎片，并朝着牢不可破的极限发展。我们还确定了碎片纵横比与其大小和分布均匀性之间的显着相关性，突出了碎片形状作为评估爆破性能以及常规分级分析的指标的潜在用途。