Assessment of an alternative implementation of the Dobry et al. cyclic strain procedure for evaluating liquefaction triggering

Abstract

Despite its fundamental basis and many positive attributes, the cyclic strain approach has not been embraced by practice for evaluating liquefaction triggering. One reason for this may be the need to perform cyclic laboratory tests to develop a relationship among excess pore water pressure, cyclic strain amplitude, and number of applied strain cycles. Herein an alternative implementation of the strain-based procedure is proposed that circumvents this requirement. To assess the efficacy of this alternative implementation, Standard Penetration Test field liquefaction case histories are evaluated. The results are compared with both field observations and with predictions from a stress-based procedure. It was found that the strain-based approach yields overly conservative predictions. Also, a potentially fatal limitation of the strain-based procedure is that it ignores the decrease in soil stiffness due to excess pore pressure when representing the earthquake loading in terms of shear strain amplitude and number of equivalent cycles.