A unified constitutive model of dual-yield surface for warm frozen soil and its verification

The constitutive model of warm frozen soil is crucial for accurately calculating the stress and deformation of frozen soil layer. Based on the modified Cambridge model and the dual-yield surface theory, taking into account the influence of cohesion and internal friction angle of warm frozen soil, the deformation characteristics of the specimen were described by the overall deformation characteristic curve εv-lnp. The hardening parameters of the current yield surface and reference yield surface of frozen soil were modified by stress path correlation factors. A unified constitutive model of double yield surface, which can effectively reflect the shear shrinkage, dilatancy, hardening and softening characteristics of warm frozen soil, is proposed. The incremental stress-strain relationship of the newly constructed constitutive model was derived within the framework of elastoplastic theory. A convenient method for determining model parameters was provided. It defined consolidation parameters and potential strength parameters that reflect the current state of frozen soil. An analysis of the dynamic cyclic relationship and interdependence between these parameters and hardening parameters was presented along the entire stress path. Experimental data were used to validate the constructed constitutive model, and the results showed that the proposed model can accurately predict the stress-strain behavior of warm frozen soil under conventional triaxial stress conditions.