Viscous effects observed in tests on an anisotropically normally consolidated silty clay: technical note : O'Reilly, M P; Brown, S F; Overy, R F GeotechniqueV39, N1, March 1989, P153–158

Abstract

Research is reported that provides quantitative evidence, for a silty clay, that the undrained shear behavior of cohesive soils is rate-dependent. A method, in qualitative terms, is suggested for modelling the general viscoelastic behavior of soils. Undrained triaxial tests were performed at a range of strain rates on specimens of an anisotropically normally consolidated silty clay derived from keuper marl. The results from these tests were used to formulate a simple model based on critical state soil mechanics concepts. The study found that the strength of K sub o anisotropically consolidated triaxial specimens of silty clay was dependent on the rate at which the test was performed. The concept of a viscous yield locus was postulated. This surface exists simulataneously with the static yield locus. The concept of viscous plasticity is found to be useful in understanding the behavior of fine-grained soils during cyclic loading in which viscous effects are important.