Characterization of internal erosion in sand kaolin soils

Abstract

International audienceThe appearance of breaches in recent hydraulic earthstructures due to internal erosion confirms that improving our physical understanding of the phenomenon is urgent. Under the effect of internal flows, earthstructures can undergo a migration of their particles, which modifies the particle size distribution and affects both hydraulic and mechanical characteristics. This paper initially presents a parametric study conducted on sand/kaolin samples. The experimental device described here consists of three modified triaxial cells used to control sample confinement, prevent any parasitic flow and survey sample large deformations. The tests reveal that internal erosion (suffusion or piping) is initiated by the transport of clay particles. The erosion rate, then, depends on the values of the different parameters considered (hydraulic gradient, clay content and filter pore opening size).La rupture par érosion interne de récents ouvrages hydrauliques en terre souligne la nécessité d’améliorer la compréhension physique de ce phénomène. Les écoulements internes peuvent engendrer une migration de particules constitutives des ouvrages hydrauliques en terre. Cette migration affecte la distribution granulométrique, modifie la porosité ainsi que les caractéristiques mécaniques et hydrauliques. Nous proposons une étude expérimentale réalisée sur des échantillons constitués de mélanges de sable et de kaolin. Le montage expérimental est constitué de trois cellules triaxiales modifiées qui permettent de contrôler le confinement des échantillons, d’éviter tout écoulement parasite et de suivre les grandes déformations des échantillons. Les essais réalisés indiquent que l’érosion interne (suffusion ou renard) est initiée par la migration des particules d’argile. Le taux d’érosion dépend du gradient hydraulique appliqué, du pourcentage d’argile et de l’ouverture des pores du filtre

Grouting below Subterranean Water: Erosional Stability Test

“…Recent experiments by Bendahmane et al [21] revealed the complex effects of confining pressure on internal erosion. The triaxial erosion test was conducted by Bendahmane et al [21,22] to measure the effects of internal flows on sand/kaolin samples. [23] developed a true triaxial system to investigate the piping potential of both cohesive and non-cohesive soils.…”

CFD–DEM Simulations of Seepage-Induced Erosion

“…The rotating cylinder test is a widely used method, due to its smaller sample volume, the ability to adequately control the stress state and the available measurements of the rate of erosion. Adopting this technique, the internal erosion depending on the grain size distribution, stress state and anisotropic condition of the system can be found [9,[13][14][15][16]. Moreover, a higher initial hydraulic gradient is observed under the triaxial extension test compared with the triaxial compression test [9].…”

Factors Affecting Failure by Internal Erosion of Geosynthetic Clay Liners Used in Freshwater Reservoirs

“…After the onset of internal erosion, the flow increases and causes a sudden increase in the hydraulic conductivity of the soil, and an increase in the displacement and flow of soil particles. Finally, the soil skeleton becomes unstable and collapses (Bendahmane et al, 2006;Chang and Zhang, 2013;Rodriguez et al, 2014;and Zhang et al, 2015). BACKGROUND Fox et al (2000) conducted hydraulic conductivity tests in flexible-wall permeameters on both needlepunched and adhesive-bonded GCLs to study the effects of the particle size of soil cover and the rate of loading.…”