Abstract: The shear strength and compressibility of soils are largely controlled by intergranular interactions. For clayey soils, however, the intergranular stresses remain elusive experimentally due to the complex physicochemical interactions between the clay minerals and pore water. To explore the effect of NaCl solution with different concentration on clay compression and to determine the intergranular stresses, a series of oedometer experiments was performed on the remolded samples prepared from a slurry mud. It is shown that at the same vertical stress, the deformation during osmotic consolidation increases with pore water concentration, and at the same concentration, the deformation during osmotic consolidation decreases as the vertical stress increases. Based on Terzaghi’s effective stress principle, the average intergranular stress is calculated based on the osmosis-induced deformation, and the dependence of intergranular stress (or the generalized osmotic pressure) variation on the pore water concentration and void ratio (i.e., dry density) is determined. This paper provides a simple and yet effective approach to determine the intergranular stresses for clayey soils, which is helpful in calibrating the constitutive model of soils with multiple coupled physicochemical processes.

Key words: clay, physicochemical interaction, intergranular stress, osmotic consolidation, generalized osmotic pressure