Strength criterion and Elastoplastic constitutive model of frozen silt in generalized plastic mechanics

摘要

Triaxial compressive tests of frozen silt were carried out under confining pressures from 0.0 to 14.0 MPa at the temperatures of -2, -4 and -6 °C. A strength criterion based upon experimental results is presented by the combination of extended Lade-Duncan strength function f_π(θ) in π-plane and f_(p-q)(p) in p-q-plane. In order to describe the deformation characteristic of frozen silt, an elastoplastic constitutive model in generalized plastic mechanics has been proposed for the nonlinear behavior of frozen silt, such as the pressure melting and crushing phenomena, strain softening/hardening characteristics and dilatation, etc., by employing an elliptical yield surface, together with a non-associated flow rule for the compressive mechanism, and two parabolic yield surfaces, together with non-associated flow rules for the shear mechanism. The validity of the model is verified by comparing its modeling results with the results of triaxial compressive tests. It is found that the stress-strain curves predicted by this model agree well with the corresponding experimental results both under low and high confining pressures.