Assessing the Potential of Internal Instability and Suffusion in Embankment Dams and Their Foundations

Abstract

Suffusion is the process by which finer soil particles are moved through constrictions between larger soil particles by seepage forces. Soils susceptible to suffusion are described as internally unstable. This technical note describes a method for assessing the potential of internal instability of silt-sand-gravel or clay-silt-sand-gravel soils based on their particle size distribution based on laboratory tests carried out by the writers and results published by others. It is shown that some commonly used methods are conservative for these soils.