Velocity of Sand Particles Transported by Upward Seepage Flow during Sand Boil

Abstract

Thus far, the focus of studies on seepage failure, known as sand boiling or the piping phenomenon, has been to determine the critical hydraulic gradient or the critical seepage flow velocity. However, the transport of soil after seepage failure also needs to be well investigated in order to estimate the damage to soil structures or the ground. This study has experimentally investigated the behavior of sand and seepage water during sand boiling induced by upward seepage flow. In the experiments, the discharge of sand particles and seepage water were measured separately during sand boiling, and their migration velocities were obtained with the measurement of the hydraulic gradient. The results have revealed that the equilibrium of the forces exerted on the sand particles, i.e., gravity, buoyancy and fluid-particle interaction, can be used to estimate the velocity of the sand particles subjected to upward seepage flow regardless of the sand type.