Study On One-dimensional Consolidation Theory Of Soft Clay With Varied Permeability And Compressibility

On the basis of the work so far available,this paper makes further study on one-dimensional consolidation theory of soft clay with permeability and compressibility varying with time or along depth.Firstly,an analytical solution is derived for one-dimensional nonlinear consolidation of double-layered soil based on the assumption that the decrease in permeability is proportional to the decrease in compressibility during the consolidation. The solution and the computer program NAODCLS developed by Xie and Leo (1999) are then used to study the one-dimensional nonlinear consolidation behavior of double-layered soil.Secondly,analytical solution is developed for one-dimensional non-homogeneous consolidation of one-layer soil and double-layered soil respectively based on the assumption that the modulus of compressibility of soil varying linearly along depth. Furthermore,the semi-analytical solution for one-dimensional consolidation problem of layered non-homogeneous soft clay stratum is presented and programmed. By using the analytical and semi-analytical solutions,the one-dimensional non-homogeneous consolidation behavior of one-layer soil and that of multi-layered soil are investigated in detail.Finally,through typical numerical examples,a comparison is made between one-dimensional nonlinear consolidation behavior and one-dimensional non-homogeneous consolidation behavior of one-layer soil and multi-layered soil.It has been shown that no matter what kind of assumption is adopted for soil in a consolidation analysis,nonlinear or non-homogeneous,the result obtained differs greatly from Terzaghi's theory. And the coefficient of consolidation is not the only parameter of soil that affects the one-dimensional consolidation behavior. Therefore,both the variation of permeability and that of compressibility of soil should be considered in a consolidation analysis to gain reasonable result.