Improvement of Soils Erodibility Characterization in the Erosion Function Apparatus by Using the Particle Image Velocimetry

The Erosion Function Apparatus (EFA) is used to characterize erodibility of a soil subjected to a fluid flow. It is mainly used in north America to predict scour phenomena around structures such as bridge piers. In a first approximation, EFA gives directly the erosion rate depending on the mean water velocity or on the shear stress. Both quantities are relied by using the Colebrook law which is a very global equation. In the scope of this study, we want to get more precise knowledge on the erosion process. In particular, we aim to characterize the turbulence induced by the flow/soil interaction. These turbulences are responsible for high local velocities in the directions parallel and perpendicular to the interface. Furthermore, it imposes to consider both the shear and normal stresses. To access these parameters, we use the Particle Image Velocimetry (PIV) into the EFA. We use both a global visualization to get access to the water column profile and a zoomed visualization on the fluid/soil interface. Simulations are done by varying the flow rate in the EFA. We use three known materials (PVC, sand, clay) to compare results given by the EFA and by the PIV. Finally, we aim at better understanding of the erosion process in the EFA flow section in order to improve results accuracy.