EXPERIMENTAL EVALUATION OF THE VISCOUS PROPERTIES 
OF SAND IN SHEAR

HASBULLAH NAWIR , FUMIO TATSUOKA and REIKO KUWANO 

ABSTRACT: Effects of wet conditions (air-dried or saturated), pressure level and dry density on the viscous properties of sand were evaluated by performing unconventional triaxial compression tests on Toyoura sand. Effects of stress path were studied to a limited extent. During otherwise monotonic loading at a constant strain rate, the strain rate was changed stepwise and/or creep loading was performed after different strain rate histories. The test results were analysed in the framework of a three-component model, called the TESRA model, that had been developed based on the results from plane strain compression tests on dense Hostun and Toyoura sands at a confining pressure of 400 kPa. The manner of viscous stress change by a change in the irreversible shear strain rate observed under the various test conditions could be represented by the same viscosity function representing the viscous properties. The viscous stress decayed with an increase in the irreversible shear strain in all the tests, while the rate of decay was noticeably larger with air-dried sand than with saturated sand. The TESRA model using the same viscosity and decay functions simulates very well the effects of viscous properties observed in the whole tests. 

Key words: constitutive modelling, creep, deformation, sand, triaxial compression tests, viscous properties (IGC: D6/D7)