LIQUEFACTION AND POSTLIQUEFACTION BEHAVIOR OF SAND

The static undrained behavior of saturated sand is shown to be dilative in triaxial compression, even in the loosest deposited state. However, the behavior in triaxial extension is contractive for relative densities of up to 60%, implying a profound anisotropy of response to undrained loading. On monotonic loading, following liquefaction, the sand always responds in a dilative manner even though it is contractive under static loading. The postliquefaction response represents continuously stiffening behavior and an approach to any residual strength is not observed, regardless of density or effective stress conditions prior to cyclic loading.