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.