Evaluation of the internal stability of well-graded silty sand through the long-term seepage test

Abstract Suffusion is the phenomenon responsible for internal erosion, and process by which finer soil particles are moved through constrictions between larger seepage forces. Generally, gap-graded known to be susceptible suffusion. Meanwhile, suffusion of well-graded silty sand resulting behavior not well understood. Moreover, previous researches on laboratory tests focused study critical hydraulic gradient, triggers instability soils within a short period time. Therefore, in this study, long-term were conducted under gradient lower than value. As result, abrupt increases permeability amount discharged observed due progressive migration particles, even at relatively low gradient.