The hydraulic gradient that causes backward erosion piping under a river levee is influenced by the scale of the levee, which is a major concern in the physical modeling. In this study, the results of 1 g and centrifuge tests performed on backward erosion piping were analyzed to facilitate a better understanding of the scale effect mechanism. The three-dimensional profile of the pipe and the flow rate of water in the pipe were observed using a transparent model levee. Although the flow in the pipe was determined to be laminar in most tests, it was found to be transient and turbulent in the coarse sand model at high g levels. The hydraulic gradient in the pipe was significantly high in the turbulent flow. Additionally, the scale effect was investigated based on the hydraulic conditions that cause sand transportation in an ideal pipe. The critical Shields number (θ_c), estimated for the model pipes, was consistent with that observed in the Shields diagram. The effects of centrifugal acceleration on the hydraulic gradient of the extending pipes can be explained by the change in θ_c with the particle Reynolds number and the hydraulic gradient in the pipe.

导致河流堤坝下向后侵蚀管道的水力梯度受堤坝规模的影响，这是物理建模中的一个主要问题。在这项研究中，分析了 1 g 和离心机测试对反向侵蚀管道的结果，以帮助更好地了解规模效应机制。使用透明模型堤坝观察管道的三维轮廓和管道中水的流速。尽管在大多数测试中确定管道中的流动是层流的，但在高 g 水平的粗砂模型中发现它是瞬态的和湍流的。在湍流中，管道中的水力梯度非常高。此外，还根据理想管道中导致输沙的水力条件研究了尺度效应。为模型管道估计的θ _c ) 与在 Shields 图中观察到的一致。离心加速度对延伸管道的水力梯度的影响可以通过θ _c随粒子雷诺数和管道中的水力梯度的变化来解释。