Liquefaction assessment of pumiceous sand with shear wave velocity approach

Natural pumiceous (NP) sands are a common volcanic soil found in the central part of the North Island, New Zealand. These NP sands have pumice components which are crushable and lightweight making them problematic in terms of engineering assessment of their geotechnical properties. Previous investigations on crushable volcanic soils indicate that penetration methods would not provide reliable estimates of their geotechnical properties. Thus, shear wave velocity (Vs) may be a promising alternative especially for estimating the cyclic resistance ratio (CRR) of crushable NP sands. In this paper, a number of cyclic triaxial and bender element tests are performed on three types of reconstituted NP sands to estimate their CRR and V-s, respectively. The results are then compared with those obtained from normal sands. The comparison indicates that using available CRR-V-s charts for normal sands would underestimate the CRR of NP sands since these materials have lower V-s and higher CRR.