This website requires JavaScript.
DOI: 10.1061/JGGEFK.GTENG-11094

Spatial and Temporal Evolution of Particle Migration in Gap-Graded Granular Soils: Insights from Experimental Observations

V. S. Ramakrishna AnnapareddyAdnan SufianThierry BoreAlexander Scheuermann
Dec 2022
This study presents physical observations and insights into particlemigration characteristics throughout the suffusion process. Using apurpose-built coaxial permeameter cell, suffusion experiments were conducted onidealised internally unstable gap-graded granular soils at varying finescontent and hydraulic loading conditions. The specimens were prepared with amixture layer comprising finer and coarser fractions underlying a coarse layercomposed of the coarser fraction alone. This enabled the finer fraction withinthe mixture layer to migrate through the coarse layer with upward seepage flow.The local porosity profile along the specimen was determined using spatial timedomain reflectometry and an inversion algorithm, which enabled the developmentof a novel field map of the difference in porosity from the initial condition.This field map provided a visual guide of the spatial and temporal variation inporosity and enabled particle migration internally within the specimen to bequantitatively characterised from onset to progression to washout. The limitingonset condition identified from the field map was shown to be comparable tothat obtained using conventional approaches, thereby providing strongvalidation for the application of porosity-based field maps. As suffusionprogressed, the height of infiltrating finer particles into the coarse layerincreased linearly with time, while the overall rate of particle migration fromthe mixture layer to the coarse layer evolved in a non-linear manner with therate of migration increasing as the specimen reached a complete mixturecondition, where the finer fraction infiltrated the entire coarse layer. Theattainment of a complete mixture condition was dependent on the fabric of thegap-graded soil ... (see PDF for full abstract).