Assessment of centrifuge modelling of internal erosion induced by upward flow conditions

A series of centrifuge modelling tests was performed in this study to evaluate the internal erosion induced by upward flow that typically occurs during the initiation phase of backward erosion piping. The study focuses on the assessment of the centrifuge scaling behaviour of models under different levels of centrifuge gravity. Tests were performed by maintaining the same model dimensions, soil and fluid properties and at centrifuge gravity ranging from 10g to 30g. The results from centrifuge tests are also compared with results under Earth's gravity or 1g. Two critical hydraulic gradients associated with the first visible movement of sand particles and the total heave were obtained. The critical hydraulic gradients obtained for the first visible movement of grains agree with the theoretical scaling law. However, the theoretical scaling is not applicable to the total heave due to the expansion of the models. Regardless, the critical gradients for first visible movement and total heave were 0.56–0.99 and 1.16–2.44, respectively, and these results agree with numerical and experimental values available in the literature. The seepage-induced stresses at the granular level were estimated and it was found that 16% of the critical total seepage stress was contributed by the viscous shear stress, while the remaining 84% was contributed by differential pressure across the grain.