Dynamic shear modulus degradation of saturated soil analysis: From the perspective of phase field theory

The idea of Phase Field Method (PFM) is introduced to depict the dynamic shear modulus degradation of saturated soil revealed in the undrained triaxial tests. The order parameter in PFM is adopted to govern the liquefaction process. Then the inherent and generalized constitutive relation among shear stress, shear strain, shear modulus and confining pressure is derived. It more complies to thermodynamics in comparison to conventional empirical model following a phenomenological description. By comparing to existed empirical model, the presented four-parameter model is validated to be of robustness and efficacy to various soil types and confining pressure levels under monotonic and cyclic loading. The simulated pore pressure varies simultaneously with modulus degradation, which is consistent with observations and energy consideration. The presented method makes it possible to apply to deformation prediction in deep excavation and other engineering practice, whilst without loss of physical interpretations.