A specific triaxial device for the study of internal erosion in cohesive soils

Abstract

The understanding of the mechanisms responsible for internal erosion of soils is in the early stages of evolution and it is apparent they depend on different parameters. Faced with such complexity, internal erosion initiation and development criteria found in the literature are directly dependent on the structure studied and are therefore diverse. Laboratory recreations of the processes are necessary to identify specific mechanisms for the initiation of the migration of particles. With this intention a parametric study on sand/clay samples was developed using an experimental device consists of three modified triaxial cells which allow controlling the sample confinement, preventing any flow around the sides of the sample and allow deformations of samples. The detection of erosion of particles is performed by an optical sensor. The first tests carried out show good repeatability and the validity of the experimental procedure. Different aspects of the initiation of internal erosion are clarified: the critical hydraulic gradient at which internal erosion initiates is shown to depend on the clay content and the filter pore opening size. If the clay content is low, the erosion of sand particles is induced and finally the skeleton of the sample is broken down.