Single-element simulations of partial-drainage effects under monotonic and cyclic loading

Liquefaction-induced seepage and pore-water pressure redistribution can locally change a sands' void ratio, such that in-situ strength and deformation behavior following an earthquake depend on the coupled diffusion process and not only on pre-earthquake soil properties. The effects of partial drainage on the monotonic, cyclic, and post-cyclic behavior of liquefied sand are explored at the element scale in this study, using the constitutive model PM4Sand [1] and the finite-difference code FLAC [2]. The ability of a critical state-based constitutive model to approximate partially drained loading responses is evaluated by comparing single-element simulations to available lab data and trends. The calibrated model is then used to examine the potential effects of partial drainage on the cyclic stress–strain behavior and accumulation of shear strains for dense-of-critical sand. The importance of liquefaction-induced seepage and void redistribution to the in-situ strength and deformation behavior of liquefied sands is discussed in view of the results of these partially drained laboratory element tests and simulations.

► Liquefaction-induced seepage may lead to localized zones of strength-loss and deformations. ► Partially drained tests are used to capture the effects of liquefaction-induced seepage. ► The numerical model successfully simulates the response under partially drained conditions. ► Critical-state framework and stress–dilatancy relationship are keys for such simulations. ► Detrimental effects of water injection increase with injection rate and decrease with density.