Nonlinear Theory For One-dimensional Consolidation Of Soft Clay Under Cyclic Loading

Although nonlinear characteristic is one of the important properties of soft clay and cyclic loading is one of the loading types common in practical engineering, there seems no study made on nonlinear theory for one-dimensional consolidation of soft clay under cyclic loading. In this thesis, based on the previous work available, a careful study was made on one-dimensional consolidation theory of soft clay under low-frequency cyclic loading with permeability and compressibility varying with time.Firstly, analytical solutions were developed for one-dimensional nonlinear consolidation of soil under some common types of cyclic loading such as trapezoidal cyclic loading, triangular cyclic loading and rectangular cyclic loading, based on the assumption proposed by Davis et al. (1965) that the decrease in permeability is proportional to the decrease in compressibility during the consolidation process of soil.Secondly, the obtained nonlinear analytical solutions were verilied through comparing them with the known analytical solution corresponding to special cases and with semi-analytical solution respectively.Finally, computer program was developed corresponding to the solutions obtained, and the nonlinear consolidation behavior of soft clay under cyclic loading, the influence of some parameters, and the law of development of the average degree of consolidation, the effective stress and the excess pore water pressure were investigated.It has been shown that the analytical solution presented herein for one-dimensional nonlinear consolidation of soil under trapezoidal cyclic loading considering the variation of permeability and compressibility of soil with time is the most perfect solution so far available for small-strain and nonlinear consolidation of soil, and all the known solutions for nonlinear consolidation of soil are the special cases of this solution. By altering the related parameters, this solution can also be deduced into the ones corresponding to simpler cyclic loading such as triangular loading, rectangular loading, etc.