Seepage failure is a common problem in engineering, and the calculation and analysis of critical hydraulic gradient are of great significance for the safety and protection of engineering. Based on the principle of discrete element method and computational fluid dynamics, the fluid–solid coupled models were established to study the critical hydraulic gradient and particle loss rate of granular soils at seepage failure. The evolution of seepage failure was divided into four stages: seepage development stage, local damage stage, volume expansion stage and overall damage stage. The validity of numerical simulation was demonstrated by comparing the critical hydraulic gradient obtained by numerical simulation and by Terzaghi’s formula. According to the fabric damage and flow velocity variation of the models at seepage failure, the influences of model size and particle size on the critical hydraulic gradient and particle loss rate were analyzed. The results indicate that critical hydraulic gradient and particle loss rate were not sensitive to changes in model size. A wide particle size distribution range resulted in large critical hydraulic gradient and small particle loss rate at seepage failure. The discrete element numerical simulation can not only be used to determine the critical hydraulic gradient of geotechnical and hydraulic engineering, but also offer a visual portrayal of the evolution of seepage failure, serving as an important complement to comprehend the intricate microscopic mechanisms underlying soil seepage failure.

中文翻译：

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离散元法和计算流体力学数值模拟颗粒土渗流破坏临界水力梯度

渗流破坏是工程中常见的问题，临界水力坡度的计算与分析对于工程的安全防护具有重要意义。基于离散元法和计算流体力学原理，建立流固耦合模型，研究粒状土渗流破坏时的临界水力梯度和颗粒损失率。渗流破坏演化分为渗流发展阶段、局部破坏阶段、体积膨胀阶段和整体破坏阶段四个阶段。通过比较数值模拟得到的临界水力坡度与Terzaghi公式的结果，证明了数值模拟的有效性。根据渗流破坏时模型的织物损伤和流速变化情况，分析了模型尺寸和颗粒尺寸对临界水力梯度和颗粒损失率的影响。结果表明，临界水力梯度和颗粒损失率对模型尺寸的变化不敏感。较宽的粒径分布范围导致渗流破坏时临界水力梯度大和颗粒损失率小。离散元数值模拟不仅可以用于确定岩土和水利工程的临界水力梯度，还可以直观地描绘渗流破坏的演化过程，是理解土壤渗流破坏复杂微观机制的重要补充。 。