Viscoelastic-viscoplastic damage analysis of transversely isotropic soft soils

Soft soils show noticeable creep, damage and transversely isotropic properties. An incremental three-dimensional Nishihara model is proposed to present the stress-strain relationship of soft soils in this paper. The Drucker -Prager yield criterion of the transversely isotropic media, the transversely isotropic flexibility matrix, and the damage law to Nishihara's constitutive model are applied to construct the transversely isotropic viscoelastic-viscoplastic damage constitutive equation of the soil. Afterwards, the constitutive model is implemented by applying a stress return mapping algorithm. We verified the proposed model by comparing the results calculated by ABAQUS with triaxial compression experimental data from Hong Kong marine deposits (HKMD) and Shanghai soft clay. Finally, based on the proposed model, we present several numerical examples to investigate the in-fluences of damage parameters on the time-dependent behaviors of saturated soft clay.