Experimental study of internal erosion on cohesive soils
Résumé
Under the internal flow, hydraulic earthstructure (dike, levee, or dam) can incur a migration of particles. This migration induced a modification of particles size distribution and a variation of hydraulical and mechanic characteristics. This modification can generate instabilities: sliding, overtopping or even failures. The occurrence of breach in new earthstructure shows the urgency to improve the design rules of this point. We propose a parametric study on sand / kaolinite samples. The experimental device consists of three modified triaxial cells which allow controlling the sample confinement, preventing any parasitic flow and surveying great deformations of samples. The first tests carried out show the good repeatability and the validity of the experimental devices. Different aspects of the initiation of internal erosion are clarified: if migration of fine particles is important, the skeleton of sample is unstable and causes the breaking down.