Abstract
As well-known, depending on density and effective mean principal stress levels, sandy soils behave in a different way under undrained shearing. For instance, loose sand usually exhibits a contractive behavior with strain-softening. Instead, dense sand typically shows a dilative response with strain-hardening. Generation of excess pore water pressure is also greatly affected, being negative during contractive state and positive during dilative state. In view of this complex behavior, to predict in a consistent way the sand shearing response over a wide range of initial void ratios and effective mean principal stress levels without the need to change the soil model parameters is not an easy task. In this paper, by using an extended general hyperbolic equation (GHE) combined with an empirical density-dependent stress-dilatancy relation, a newly developed model for describing monotonic undrained torsional shear behavior of sands using a single set of soil parameters is presented. Its validity is demonstrated for the case of Toyoura sand specimens consolidated at various levels of void ratio and effective mean principal stress.
