A rate-dependent constitutive model for saturated frozen soil considering local breakage mechanism

Abstract

A rate-dependent constitutive model for saturated frozen soil is vital in frozen soil mechanics, especially when simultaneously describing the nonlinearity, dilatancy and strain-softening characteristics. The distribution of the non-uniform strain rate of saturated frozen soil at the meso-scale due to the local ice-cementation breakage is described by a newly binary-medium-based homogenization equation. Based on the field-equation-based approach of the meso-mechanics theory, the interaction expression of the strain rate at macro- and meso-scale is derived, which can give the strain rate concentration tensor at different crushed degrees. With the thermodynamics and empirical assumption, a breakage ratio in the rate-dependent form is determined. This overcomes the limitations of the existing binary-medium-based models that are difficult to simulate rate-dependent mechanical response. Based on these assumptions, a newly binary-medium-based rate-dependent model is proposed considering both the ice bond breakage and material composition characteristics of saturated frozen soil. The proposed constitutive model has been validated by the test results on frozen soils with different temperatures and strain rates.