UNIAXIAL COMPRESSION TEST OF UNSATURATED MASADO UNDER CONSTANT DEGREE OF SATURATION CONDITION AND ITS MODELING

Abstract

Soils in surface ground are usually unsaturated. Proper modeling of the characteristics of
unsaturated soil is therefore absolutely needed. However, due to its complicated mechanical behavior,
establishing a constitutive model for unsaturated soil is far more difficult than that for saturated soil. In this
research, uniaxial compression tests were firstly conducted on unsaturated Masado (Decomposed granite)
under constant degree of saturation condition to investigate the mechanical behavior of the soil at different
degree of saturation. Then, based on the test data, the performances of previously proposed elastoplastic
constitutive model for unsaturated soil were checked carefully, taking the Bishop-type skeleton stress and the
degree of saturation as the state variables. It is found that the mechanical behavior of the unsaturated Masado
can be properly described by the proposed elastoplastic constitutive model that takes the skeleton stress and
the degree of saturation as the state variables.
Keywords: Unsaturated Soil, Degree of Saturation, Constitutive Model, Uniaxial Compression Test