Two-yield surface constitutive model for fine sand in consideration of dilatancy and strain softening

On the basis of traditional model a modified elastoplastic constitutive model for fine sand which can reasonably describing the characteristics of dilantancy and strain softening is proposed.This two-yield surface model reflects the mechanism of shear deformation and mechanism of compressive deformation simultaneously.The traditional dilatancy equation of Cam-clay model is modified and the relativity between phase transformation stress ratio and initial effective pressure is considered.In order to describe the characteristic of strain softening,a strain softening equation using the stress ratio at steady state to peak state is formulated.The validity of this model is verified by several test results for fine sand in Shanghai.