On the consolidation of sedimenting clays

A comprehensive formulation for the estimation of excess pore pressures during consolidation, when sedimentation takes place, is presented. The development is based on the general nonlinear behaviour of the soil whose properties are assumed to vary with depth and time. Because finite strains entail large changes in soil properties, of which compressibility and permeability are the main factors, these properties are related to effective stress by power laws. By combining these with other assumptions made in the classical Terzaghi theory, together with the vertical equilibrium of the soil–water system including the self-weight of the soil, the equation governing the process of consolidation in a sedimenting clay was derived.The consolidation equation thus obtained is nonlinear. Previously published equations governing linear and nonlinear consolidation behaviour of clay soils may be derived from the general nonlinear equation. The data from the deltaic deposits of the continental shelf off Louisiana are studied and the results of applying the developed nonlinear equation to the history of these deposits agree well with the observations.