CONSTITUTIVE RELATIONS FOR PARTIALLY SATURATED SOILS CONTAINING GAS INCLUSIONS

This paper is concerned with a mathematical description of the undrain ed response of partially saturated soils having a continuous liquid ph ase (water) and a gas in the form of discrete bubbles. Two types of so il structures are considered. First is the case in which the gas inclu sions, of size much smaller than the average particle size, are entrap ped in the water phase. Second is the case in which the comparatively larger gas bubbles are embedded in the saturated soil skeleton. The fl uid phases are assumed to be separated by boundaries across which disc ontinuities in pressure exist due to surface tension. The soil is trea ted as a three-phase composite medium and the mechanical properties ar e described in terms of average stress/strain measures in all constitu ents. The mathematical formulation incorporates the average pore/bubbl e size as an independent material parameter governing the mechanical r esponse.