Shear wave velocity-based assessment of liquefaction resistance of natural pumiceous sands Available to Purchase

Over the last few decades, a number of laboratory and field testing techniques have been developed to evaluate the liquefaction resistance of hard-grained sands, while very few investigations have been performed on crushable volcanic soils. Natural pumiceous (NP) soils, a type of volcanic soil commonly found in the North Island of New Zealand, are problematic due to their crushability and lightweight features. Therefore, questions have been asked as to whether existing empirical correlations for liquefaction assessment derived primarily from hard-grained sands would be applicable to NP sands. Previous investigations on crushable soils indicate that penetration methods would not provide reliable estimates of their cyclic resistance ratio (CRR) due to particle crushing occurring during penetration. Thus, the measurement of shear wave velocity (V_s) may be a promising alternative for liquefaction assessment of NP sands. In this paper, a number of cyclic triaxial and bender element tests were conducted on reconstituted NP sands to estimate their CRR and V_s, respectively. The laboratory results indicated that, for the same relative density and effective confining pressure, NP sands have considerably lower V_s and higher CRR compared with hard-grained sands. Thus, using currently available CRR–V_s curves developed for hard-grained sands would result in significant underestimation of the liquefaction resistance of NP sands.