Influence of sand and low plasticity clay mixtures on the liquefaction and postliquefaction behavior

Abstract

Liquefaction resistance changes with the presence of certain amount of fines in sand but literature related to laboratory and field investigations and the ground behaviour under earthquakes have clearly highlighted the conflicting evidence of the presence of fines on the liquefaction behaviour of sand-fines mixtures particularly low plasticity clay fines. Some studies have indicated decrease in liquefaction resistance with increase in plasticity and vice-versa. The postcyclic undrained shear behaviour of sand and low plasticity are controlled by excess pore pressure ratio and the behaviour is independent of density and confining pressure. In this paper, a series of undrained stress controlled cyclic triaxial shear tests and monotonic undrained shear loading were conducted on reconstituted sample of sand-fines mixtures to evaluate the liquefaction and postliquefaction behavior. Sand was procured from Cauvery river bed, Karnataka, India and locally available low plasticity clay fines were used to prepare sand-fines mixtures. The results indicate that Cyclic Resistance Ratio (CRR) increases with relative density and the post cyclic monotonic strength show increased stress at Ru = 0.