Laboratory Investigation of Stress State and Grain Composition Affecting Internal Erosion in Soils Containing a Suspended Cut-off Wall

다국어 초록 (Multilingual Abstract)

Cut-off walls have been widely used to control seepage in dams and their foundations for over 100 years. The soil at the bottom of a cut-off wall is usually under complex stress and composed of various particles with different contents. In this study, the effects of the stress state and grain composition on the evolution of internal erosion were investigated in sandy gravel foundations containing a suspended cut-off wall. The following observations were made based on the experimental results: (1) The fine-particle content of the soil sample considerably influences the evolution of internal erosion. For high fine-particle content, particles are likely to clog under the downward flow; however, for low fine-particle content, the downward flow assists the migration of fine particles. (2) Deviatoric stress considerably influences the soil structure. The soil sample is compressed under low deviatoric stress; however, it undergoes dilatancy under high deviatoric stress. (3) Dilatant behavior is also controlled by confining stress. The higher the confining stress, the higher is the deviatoric stress applied on the soil sample, which produces dilatancy, and the smaller is the volumetric expansion. The obtained results will enhance the understanding of the progression mechanism of internal erosion around suspended cut-off walls.

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