Liquefaction Mechanism of Unsaturated Volocanic Sandy Soils

Liquefaction of Unsaturated Sand Considering the Pore Air Pressure and Volume Compressibility of the Soil Particle Skeleton

“…However, in this study, aˆne clean sand known as Toyoura sand was used as the testing material in order to explain the general liquefaction state of unsaturated soils. Other publications are available for reference purposes with regard to tests carried out on volcanic sandy soil (Kazama et al, 2006;Unno et al, 2006b). Figure 1 shows the grain size distributions of the Toyoura sand used in this study, which has noˆne content and a speciˆc gravity of 2.643.…”

“…In theˆgure, the circle mark eliq depicts the void ratio change required to obtain a state of complete liquefaction as calculated by Eq. (8). Since the structure of the soil is loose, the soils liquefy easily because of their high compressibility.…”

“…Because the slope material had to be under an unsaturated condition from the surface to a certain depth, the authors suspected that unsaturated soil had made a phase transformation from a static condition, as a solid phase, to a ‰uid-like phase after shaking. In order to clarify the mechanism, fundamental research on unsaturated volcanic soils after subjecting them to cyclic shear has been carried out by the authors (Unno et al, 2006a; Kazama et al, 2006). In these studies, it was shown that a shaking disturbance aŠects the moisture state of soil, and that the liquefaction potential of unsaturated soil can be evaluated by taking the volume compressibility of the soil particle structure, the degree of saturation and the conˆning pressure into account.…”

Lessons from Earthquakes in Recent Times and their Effects on the Development of Geotechnology

“…Despite that, the ‰ow failure of unsaturated ground during an earthquake was reported by JGS (2003). Since then, active studies on the liquefaction of unsaturated soils have been conducted with high but not full degree of saturation (Kazama et al, 2006 andNakazawa et al, 2007). In contrast, few studies have been done with a focus on examining the dynamic strength of unsaturated soils under a lower degree of saturation.…”

Liquefaction Resistances of Unsaturated Non-Plastic Silt

“…Relationship between liquefaction resistance ratio and potential volumetric strain with the empirical curve obtained by Okamura and Soga (2006) relationship between liquefaction resistance ratios and the potential volumetric strain, which enables the estimation of the liquefaction resistance for partially saturated sand. Kazama et al (2006) and Unno et al (2008) performed cyclic triaxial tests on a partially saturated volcanic sand and clean sand. They reported that the measured volumetric strain of the specimens when the liquefaction condition was reached was approximately the same as the potential volumetric strain, which strongly support the hypothesis of theˆrst mechanism.…”