Assessment of the Undrained Response of Sands under Limited and Complete Liquefaction

The technique presented deals with the assessment, based on drained test behavior and formulation, of the undrained postcyclic stress-strain behavior of sands under limited or complete (full) liquefaction and its associated strength. At present, there is no particular procedure that allows assessment of such undrained postcyclic behavior that could develop full (pore-water pressure ratio, r(u) = 1) or limited (r(u) < 1) liquefaction. The prediction of the undrained postliquefaction (full or limited liquefaction) response presented here is based on basic properties of sand such as its relative density (D(rc)) [or (N(1))(60) blowcount], the effective angle of internal friction (phi), the roundness of the sand grains (rho), and the drained axial strain at 50% stress level (epsilon(50)). The technique presented accounts for the excess pore-water pressure induced by cyclic loading (Delta u(c)) and the postcyclic excess pore-water pressure generated under undrained monotonic loading (Delta u(d)).