Implementation of a new liquefaction potential assessment linking SPT and V_s data to address soil density and fabric effect

Abstract

A new liquefaction potential evaluation method using both Standard Penetration Test (SPT) and shear wave velocity (V_s) data is proposed in consideration of the effects of density and soil fabric on liquefaction characteristics. Through a series of chamber tests, it has been confirmed that for specimens created under the same density and confining stress level but of different soil fabric as reflected from V_s values, the measured SPT blow counts (N-value) did not change with different V_s at the given relative density. In our proposed evaluation method, the cyclic resistance ratio, CRR is first estimated from existing SPT-based approaches, and taken as a reference field resistance representing mainly density effect. A corresponding normalized V_s value could be back-calculated from V_s-based triggering at the same CRR. To account for the soil fabric influence, the implied V_s is compared to the field measurement and a revised in-situ CRR is determined through a previously proposed empirical V_s-CRR relationship where the relative density is normalized. The applicability of the new method is demonstrated through liquefaction case histories collected in Japan and from an open source global database.