Liquefaction potential of volcanic soil in undrained cyclic triaxial tests

Volcanic grains are porous, light-weight, fragile and have very rough surfaces. They possibly show breakage of grains and reduction of the asperities. These characteristics generally result in a different response under cyclic loading in comparison with hard-grained sands. This paper investigates the cyclic behavior of a volcaniclastic silty sand with non-plastic/low plasticity fines using undrained cyclic triaxial tests on undisturbed and reconstituted specimens sourced from the foundation soils of an earth dam in Southern Italy. The undrained response of both disturbed and undisturbed specimens is thoroughly consistent with published trends on volcanic soils, and moreover it is significantly different from hard-grained sands behavior. It is further shown that liquefaction resistance of undisturbed specimens is higher than that of reconstituted ones, thus highlighting the strong influence of fabric.