Energy-based liquefaction assessment of partially and fully saturated clayey sands

Soil deposits containing some amounts of plastic fines (i.e., clay) with different saturation conditions can behave differently under seismic loading, which needs to be considered properly in the design practice. The energybased method (EBM) has been consistently employed as an alternative means to evaluate the liquefaction resistance of soils. Therefore, an experimental study was undertaken to characterize the coupled effects of clay inclusion and saturation degree on the liquefaction resistance and cyclic response of Toyoura sand, using the energy concept. The experimental results showed that the addition of clay and saturation degree significantly affected not only the liquefaction resistance and capacity energy to liquefaction but also the failure mechanism of the Toyoura sand. It was also found that the evolutions of excess pore water pressure, double amplitude axial strain, and stiffness degradation with dissipated energy were greatly influenced by adding clay and change in saturation degree. A novel energy-based model was developed that uniquely correlates the capacity energy to cyclic resistance for all fully and partially saturated clean/clayey sands. For the first time, a unique model was established that directly links the state parameter, under the critical state soil mechanics (CSSM) framework, to capacity energy, EBM, in saturated clean/clayey sands.