APPLICATION OF TERZAGHIS CONSOLIDATION THEORY TO NEARLY SATURATED SOILS

Terzaghi's one-dimensional consolidation theory is modified to account for the compressibility of fluid and solid phases. The proposed modif ied equations can be used to analyze the consolidation response of uns aturated soils over the saturation range where the gases remain in an occluded form (generally within a range between 80 and 100% saturation ); however, such applications are subject to the same limitations and idealizations implicit in Terzaghi's classical consolidation theory. T he purpose of this note, therefore, is to offer a simple solution and not to unravel the complexities involved in general analysis of flow a nd deformation response of unsaturated soils. The proposed approach in volves defining the consolidation coefficient, and hence the time fact or, in terms of an equivalent fluid compressibility. This equivalent f luid is assumed to represent the compressibility characteristics of al l the compressible phases that constitute the soil skeleton. The propo sed generalized form of Terzaghi's consolidation equations is shown to qualitatively capture the consolidation behaviour of unsaturated soil s. To test the validity of the formulations presented, one-dimensional oedometer tests were performed on specimens of Lantz clay that had be en prepared at different saturation levels; satisfactory agreement was achieved between the theoretical and measured data at two states of s aturation.