Experimental Study on the Effects of Initial Conditions on Liquefaction of Saturated and Unsaturated Sand

AbstractSoil liquefaction is one of the most common geohazards that is often the root cause of damage and disruption to the civil infrastructure systems. It has been tacitly considered to only occur in loose saturated sand or low-plasticity silts. A series of strain-controlled cyclic loading tests on saturated and unsaturated Nevada sand has been conducted to reveal the fact that not only saturated soils, but also unsaturated soils, can be liquefied when certain test conditions are satisfied. In this laboratory study, different initial conditions of soil specimens are tested. These conditions include the following: relative density (30 and 70%), effective confining stress (50 and 200 kPa), and degree of saturation (90, 95, and 100%). All specimens, except the one with 70% relative density, 200 kPa confining stress, and 90% degree of saturation, reach liquefaction at the end of the tests. Although it is well established that liquefaction resistance increases with relative density and confining stress and decreases with the degree of saturation, some quantitative guidance to evaluate liquefaction of soils, especially under their unsaturated states is provided from this study. These guidelines can serve as the basis to transform current geotechnical design procedure when unsaturated soils are involved.