Numerical investigations on liquefaction potential of saturated silty sands

Abstract

In this study, cyclic triaxial tests and centrifuge tests using silty sands were simulated in OpenSees to investigate the effect of fines on the liquefaction potential of saturated silty sands. Choice of proper density index was found to be extremely important for characterizing the liquefaction potential of silty sand, as different conclusions can be derived if we use different density indices for comparing experimental results. Laboratory results reported by past researchers were found to be mutually contradictory, but such contradictions were resolved by using a proper desity index. Laboratory investigations were commonly conducted by keeping relative density or void ratio fixed to study the effect of fines on liquefaction potential. However, it was found that a unique relation between cyclic stress ratio, number of loading cycles required for triggering liquefaction, and equivalent granular void ratio (e*) can be established for silty sand with fines content less than thethreshold fines content. Furthermore, finite element method, using an advanced constitutive model with calibrated parameters, was found to be effective in simulating the dynamic responses of silty sand but it significantly underestimated the settlement of free field due to liquefaction. Moreover, parametric studies showed that the cyclic resistance of silty sand can be unified by the equivalent granular void ratio.