Scaling effects of g-level and fluid viscosity on flow velocity through transverse cracks in embankment dams and levees
Scaling effects of g-level and fluid viscosity on flow velocity through transverse cracks in embankment dams and levees
Flow through transverse cracks in embankments is a potential failure mode that can lead to concentrated leak erosion (CLE) and embankment failure. Current practice to assess whether CLE will propagate compares the hydraulic shear stress imparted by the fluid on the crack walls to the critical shear stress of the soil. Hydraulic shear stress, and by relation, fluid velocity through the crack, depends on factors including crack geometry, change in head, and fluid viscosity. An experimental parametric study was conducted to evaluate the scaling factors associated with g-level and fluid viscosity on flow velocity through a known crack geometry. Centrifuge models comprising homogenous embankments with 1.5H:1V slopes were constructed using low plasticity clay compacted to 95% standard Proctor maximum dry density. Tests were performed at 1g, 20g, and 40g, using 1 cPs, 7 cPs, and 40 cPs fluid. For each test, a 4.7 mm nominal width transverse crack was cut into the embankment, and a reservoir maintained constant head on the upstream side of the crack. The scaling relationships for flow velocity through the cracks with respect to g-level and fluid viscosity are discussed. The study finds that free-surface flow velocity through the cracks is generally governed by Froude number similitude and not Reynolds number similitude. This supports scaling the velocity of surface flows through cracks by a factor of 1 between model scale and prototype scale.
Mark Bancroft; Kil-Wan Ko; Jason T. DeJong; M. Gardner; Jack Montgomery; Grace Chen; Steven Friesen
11th International Conference on Physical Modelling in Geotechnics (ICPMG2026)
Session 2: Scaling laws and fundamentals
https://doi.org/10.53243/ICPMG2026-324