Evaluation of flow liquefaction and liquefied strength using the cone penetration test: an update

A method to evaluate the susceptibility of soils to undrained strength loss that could result in flow liquefaction as well as a method to estimate the resulting liquefied undrained shear strength of predominately sand-like soils using the cone penetration test (CPT) were outlined by Robertson in 2010. Based on published data and recent case histories, this technical note describes a recommended update to these methods to estimate the large-strain liquefied or remolded undrained shear strength for both sand-like and clay-like soils as well as soils that transition from sand-like to clay-like. The proposed update acknowledges that soil behavior can vary from sand-like to clay-like and that CPT interpretation to estimate large-strain undrained shear strength changes due to the changing drainage conditions during the CPT. The updated method builds upon previously published data combined with recent experience and case histories.