This paper proposes a coupling model for evaluating the occurrence of piping erosion under free flow and seepage flow. The model employs the Navier–Stokes equation to describe free water flow in a pore channel and the Brinkman-extended Darcy equation to describe seepage flow in soft soils. The expression of the critical hydraulic gradient of piping erosion was derived based on the force limit equilibrium of a single soil particle within the pore channel. The results of the theoretical calculation of the proposed model are in good agreement with the results obtained by two classical piping tests. However, compared with existing formulas, the proposed formula has better generalization and accuracy. Moreover, the critical hydraulic gradient varies linearly with the soft soil porosity (negative correlation), the soil particle diameter (positive correlation) inside the pore channel, and the stress jump coefficient (positive correlation) at the interface between the pore channel and the soft soils.

本文提出了一种评估自由流和渗流下管道侵蚀发生情况的耦合模型。该模型采用纳维-斯托克斯方程描述孔隙通道中的自由水流，并采用布林克曼扩展的达西方程描述软土中的渗流。基于孔道内单个土颗粒的力极限平衡，推导了管道侵蚀临界水力梯度的表达式。该模型的理论计算结果与两次经典管道试验获得的结果非常吻合。然而，与现有公式相比，所提出的公式具有更好的泛化性和准确性。此外，临界水力梯度与软土孔隙度（负相关）、孔道内土粒径（正相关）以及孔道与软土界面处的应力跳跃系数（正相关）呈线性变化。土壤。