This paper presents a numerical study of erosion–slippage failure of soil between piles caused by underground pipe leaking using the coupled CFD–DEM (computational fluid dynamics–discrete element method) approach. By tracking the change in particles migration and flow fluid during numerical simulation, the development mechanism of erosion–slippage failure is clarified on both microscopic and macroscopic scale. Three stages during this failure (initial, developing and failing) are proposed, and the definition of critical water pressure at leaking hole is confirmed by the comparison of particles and fluid field. Four crucial factors for soil to resist erosion–slippage failure are discussed: pile spacing, degree of density, soil–pile friction coefficient and soil gradation. Pile spacing has the most obvious influence on anti-erosion ability of soil. The degree of density determines whether the erosion–slippage failure happens in an instantaneous way or a continuous way. The increase in friction coefficient can enhance the resistance of soil to erosion to small extent. Soil gradation shows a great influence on migration of fine particles and strength of soil structure.

本文使用CFD-DEM（计算流体动力学-离散元）耦合方法，对地下管道泄漏引起的桩间土壤冲蚀-滑动破坏进行了数值研究。通过在数值模拟过程中跟踪颗粒迁移和流动流体的变化，在微观和宏观尺度上阐明了侵蚀-滑动破坏的发展机理。提出了该破坏过程中的三个阶段（初始，发展和破坏），并通过比较颗粒和流场来确定泄漏孔处的临界水压。讨论了土壤抵抗侵蚀-滑移破坏的四个关键因素：桩间距，密度，土桩摩擦系数和土层。桩距对土壤的抗侵蚀能力影响最大。密度的程度决定了侵蚀-滑移破坏是瞬时发生还是连续发生。摩擦系数的增加可以在较小程度上增强土壤的抵抗力。土壤分级对细颗粒的迁移和土壤结构强度影响很大。