Influence of Density on the Static Liquefaction Characteristics of a Sandy Kutch Soil

Loose sands and very loose silty sands are most susceptible to static liquefaction among all the soil types. The undrained response of granular soils is controlled by several factors including material and stress states. Loose granular soils under undrained conditions develop solid–fluid instability due to the generation of excess pore water pressure consequently leading to static liquefaction. The increased pore pressure indicates loss in effective confining pressure thereby resulting in reduced mobilized shear stress. In the recent past, a number of incidents of static liquefaction have occurred in dams across the world, causing extensive damage to life and property. In this study, the effect of relative density on the static liquefaction characteristics including undrained brittleness, collapse potential, and liquefaction potential has been explored, for a soil from the Kutch region of India. This region was severely affected by the devastating earthquake of 2001. To carry out the study, isotropically consolidated undrained compression triaxial tests were performed with frictional end rigid boundary conditions. The liquefaction resistance was observed to decrease with the increase in void ratio; however, pore pressure ratios greater than 0.85 were exhibited at void ratio corresponding to the relative density of 80% signifying intense strain softening. The samples showed an increasing trend in peak shear stress with increasing relative density. Also, the various liquefaction indices decreased with relative density, particularly above 60%. The study showed that the soil under study had a high tendency for static liquefaction.