Abstract: Starting with the first and second laws of thermodynamics, the free energy function and dissipation potential function are discussed; then the corresponding yield loci, flow rules as well as hardening rules are deduced in a systematic manner. Within the framework of critical state soil mechanics, a new method that combines the anisotropic model based on thermodynamics and specific rotation hardening rule is presented for dense sand. Then triaxial drained and undrained test curves are simulated with given model parameters; and the influence of model parameters on curve shape is discussed briefly. The results prove the validity of this method, which covers the perplexing triaxial test curve in dense sand by adopting variational rotation directions, as well as guarantees the consistence of dilatancy function with yield locus because of the thermodynamics basis involved. The models constructed through this method have the advantages of the strict structure, the extensive applicability and the simpleness.

Key words: dense sand, thermomechanics, elastoplastic model, triaxial test