Analytical Solution for One-Dimensional Nonlinear Consolidation of Saturated Double-Layered Soil Subjected to Cyclic Loadings

Cyclic loading-induced consolidation behavior of soft soil is of great interest for the analysis of offshore and onshore structures. In this study, an analytical solution for one-dimensional (1D) nonlinear consolidation of saturated double-layered soil under various types of cyclic loadings such as trapezoidal cyclic loading, rectangular cyclic loading, and triangular cyclic loading was derived. The proposed solution was subsequently degenerated into solutions for special cases and compared to the existing solutions. The degenerate solutions show good agreement with the existing results, which proves that the proposed solutions are more general ones for 1D nonlinear consolidation of saturated soils under time-dependent loading. Finally, a comprehensive parametric study was conducted to investigate the influences of different layer parameters, drainage conditions, and loading parameters on nonlinear consolidation of saturated double-layered soil under cyclic loadings.

Nonlinear consolidation theory for prefabricated vertical drains with elliptic cylindrical assumption

Based on the influence of the non-linear change in the consolidation process of permeability coefficient and compressibility of soft soils and the theory of elliptic cylinders, derived the control equation of the nonlinear consolidation of the vertical foundation of the strip plastic drainage board. Further, according to the complete orthogonal space theory, the equivalent polynomial analytical expression of the nonlinear term is given. Then, the analytic solutions of the nonlinear consolidation are given, and through numerical calculation and verification analysis, it is considered that the Indrarantna (2005) approximation has a relatively small error at Cc/Ck (close to 1) and Nu (<4), but when Cc/Ck (difference from 1) and Nu are large (>4), the error is large.

Finite Element Study on Calculation of Nonlinear Soil Consolidation Using Compression and Recompression Indexes

The coefficient of consolidation is traditionally considered as a constant value in soil consolidation calculations. This paper uses compression and recompression indexes to calculate the solution-dependent nonlinear compressibility, thus overconsolidation and normal consolidation are separated during the calculations. Moreover, the complex nonlinear consolidation can be described using the nonlinear compressibility and a nonlinear permeability. Then, the finite element discrete equation with consideration of the time-dependent load is derived, and a corresponding program is developed. Subsequently, a case history is conducted for verifying the proposed method and the program. The results show that the method is sufficiently accurate, indicating the necessity of considering nonlinearity for consolidation calculations. Finally, three cases are compared to reveal the importance of separating the overconsolidation and normal consolidation. Overall, this study concluded that it is inadequate to consider just one consolidation status in calculations, and that the proposed method is more reasonable for guiding construction.