Experimental Study for Assessing the Onset of Suffusion and Suffosion of Gap-Graded Soil

A modified triaxial shear test apparatus was used to investigate the factors influencing the onset of suffusion (migration of fine particles from soil without a change in volume) and suffosion (migration of fine particles from soil with a change in volume or a local collapse of the soil structure). A new criterion was developed to predict the seepageincited internal instability phenomena of suffusion or suffosion. A flexible wall permeameter, a seepage flow control system, and volume change measurement instrumentation were designed and manufactured for the study.