A Constitutive Model For Unsaturated Soil Based On The Principle Of Generalized Effective Stress

ABSTRACT:Although a number of constitutive models for unsaturated soils exist in the literature, some fundamental questions have not been fully answered. In this paper, the progress in constitutive models for unsaturated soils is briefly reviewed at first. Based on The principle of generalized effective stress for unsaturated soils proposed by Zhao et al. (2008) and A new modelling approach for unsaturated soils using independenst stress variables proposed by Sheng et al. (2008), the paper presents an elastoplastic model coupling hydraulic and mechanical behaviour of unsaturated non-expansive soils. The paper provides interrelated expressions and constitutive relation of yield stress and volume change behaviour by calculating both influence of degree of saturation and suction, and then provides a systematic validation of the equation. The proposed elastoplastic constitutive model answered questions related to (i) the change of the yield stress with soil suction, (ii) modeling slurry soils, and (iii) the smooth transition between saturated and unsaturated soil states. The proposed model seems to be more flexible in modeling different types of unsaturated soils than most models in the literature.