A disturbed state concept-based solution for nonlinear consolidation of soils

This paper proposes a simplified solution for the nonlinear consolidation of soft soils under a wide range of loading using the disturbed state concept. The mechanical properties of soil are stress-dependent, and this affects the soil's compressibility and permeability. However, Terzaghi's conventional theory of consolidation neglects these changes in soil parameters during the consolidation process, which limits its applicability beyond materials with constant parameters. Other sophisticated theories for nonlinear consolidation require advanced calculations that cannot be performed without special programs and codes. The proposed method uses the disturbed state concept to determine the solutions of the nonlinear partial differential equation of consolidation based on the solutions of the linear consolidation partial differential equation in two reference states and a sigmoid form state function for interpolation. The state function is derived using the nonlinear finite difference method. The proposed method accounts for both material nonlinearity arising from changes in the compressibility and permeability of the soil layer and geometrical nonlinearity arising from changes in the thickness of the soil layer. The proposed method adopts the solutions of Terzaghi's theory of consolidation to the solutions of nonlinear consolidation. The results of the proposed method are verified using the results of the nonlinear finite difference method and laboratory data published in the literature. The verification of the results indicates the accuracy of the proposed method.