The liquefaction of cohesionless soils has traditionally been considered only for fully saturated soils. However, the unsaturated soils, which are mostly near the ground surface and have low overburden pressure, may liquefy during earthquakes. In this study, the tendency of the soil in unsaturated condition to liquefy is studied by performing suction-controlled cyclic triaxial tests on silty sand. In order to maintain parity between saturated and unsaturated specimens, the failure due to liquefaction was considered when the double-amplitude strain reached a value of 5%. It was observed that soil specimen at an induced matric suction of 2 kPa required thrice the number of loading cycles to liquefy the specimen when compared to that for a saturated specimen. This demonstrates that though unsaturated soils near saturated condition may liquefy due to cyclic mobility, however, greater stresses and/or higher number of loading cycles are required to liquefy them.
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