Study on particle loss-induced deformation of gap-graded soils: role of particle stress

Deformation induced by finer particle loss is an important phenomenon during suffusion of gap-graded soils. This study focuses on the role of particle stress played in the particle loss-induced volumetric deformation. Discrete element simulations are performed to generate loss of finer particles with prescribed stress contribution, i.e. the contribution of particle stress to the macroscopic stress. Variations of volumetric strain, ε_v, with the stress contribution, C_σ^e, of eroded finer particles present two distinct patterns, that is, transition pattern, i.e. ε_v has extremely small values at relatively small C_σ^e and increases rapidly as C_σ^e exceeds the transition point near C_σ^e = 0.01%, and constant pattern, i.e. ε_v reaches a rather large value at extremely small C_σ^e and varies little with the increment of C_σ^e. A transformation from constant to transition pattern is observed for the ε_v–C_σ^e curves with the increment of the coordination number, Z_strong, of the load-carrying skeleton. The threshold of Z_strong for the transformation is around 3.71 for a relatively small eroded fraction (≤ 10%), while it is 3.96–4.09 for a relatively large eroded fraction (≥ 30%), in which the eroded fraction is the volume percentage of the eroded finer particles within the finer fraction.