Laterally confined consolidation of slurried fine-grained soils, and critical state parameters

Abstract

Abstract A series of one-dimensional, laterally confined consolidation tests was carried out on reconstituted and slurried clays. Reconstituted clay, prepared as a slurry, underwent loading and unloading in a rectangular cell in which null pressure gauges were installed in the walls, allowing reliable measurement of lateral stress. The results of the virgin loading stages showed equivalency between the compression index, $$C_{c}$$ C c , which relates the void ratio to the vertical effective stress, and the critical state compression parameter, $$\lambda$$ λ , which relates void ratio to the isotropic or mean effective stress, as long $$\lambda$$ λ is obtained from one-dimensional compression. This equivalency is shown to be consistent with constant $$K_{0}$$ K 0 during virgin loading. On the other hand, during unloading, the expansion indices differed significantly, and non-equivalency was demonstrated between the parameters $$C_{e}$$ C e , the expansion index, and the critical state parameter, $$\kappa$$ κ , consistent with a non-constant unloading earth pressure coefficient, $$K_{0} ^{\prime}$$ K 0 ′ . Isotropic consolidation tests performed on the same soils yielded compression indices, $$\lambda$$ λ , consistently slightly lower—80–86% of the laterally confined values, suggesting that compressibility may depend on the imposed stress path, while expansion indices, $$\kappa$$ κ , were equal to the one-dimensional values. A rational expression for the relationship between $$K_{0} ^{\prime}$$ K 0 ′ and $$K_{0}$$ K 0 , in terms of the expansion indices relative to vertical and lateral stress, respectively, $$C_{e}$$ C e , $$C_{e,h}$$ C e , h , is presented.