Comparisons of cyclic response and reconsolidation volumetric strain of saturated coral sand and siliceous sand

Abstract

Reported here are undrained cyclic torsional shear tests and reconsolidation tests carried out to compare the characteristics of the undrained cyclic response and reconsolidation volumetric strain (ε v) of saturated coral sand and siliceous sand (Nanjing fine sand and Ottawa sand). An important finding is that the cyclic resistance ratio of saturated coral sand increases with increasing relative density (D r) and decreases with increasing consolidation confining pressure () under isotropic consolidation. For given D r and the liquefaction resistance of saturated coral sand is higher than that of saturated siliceous sand. There is good correlation between ε v and the excess pore water pressure (u e) of sand before liquefaction. For a given consolidation stress with increasing maximum shear strain (γ max), ε v of saturated coral sand tends to stabilize at a value defined as the ultimate reconsolidation volumetric strain, which decreases with increasing D r. Also, ε v of saturated siliceous sand is less than that of saturated coral sand, and with increasing and D r, the measured ε v approaches the theoretical post-liquefaction maximum volumetric strain. Prediction models for ε v of saturated coral sand are developed based on the liquefaction level and γ max, respectively.