On The Theory Of Large-Strain And Non-Linear Rheological Consolidation Of Soft Clayey Soils

The theory for consolidation of soft soils has been well developed since 1925. However, although soft calyey soil stratum is actually layered with non-linear and rheological propertis, no theory of consolidation is available so far that can take consideration of all these basic properties of soft soils but only one or two of them. It is therefore of great theoretical and practical significances to make carefully and systematically studies on the theories of both small-strain and large-strain consolidation of layered soft clayey soils with non-linear and rheological properties.In this Dissertation, the non-linear and rheological as well as layered properties of soft soils were firstly all taken into consideration in the studies of the large-strain consolidation theories. Analytical solution was obtained for one-dimensional large-strain and non-linear consolidation of single-layered soil under time-dependent loading on the basis of some simplifications. Meanwhile, semi-analytical method was proposed for solving more complicated consolidation problem and corresponding computer code was developed for one-dimensional large-strain consolidation analyses, in which, complicated factors such as selfweight, non-linear and rheological properties of soft soils can be all taken into consideration. The correctness of the method and that of the code were verificated through comparing the results with those obtained from available analytical solutions. Further more, a comprehensive investigation into the influences of relevant factors on the consolidation and the differences between small-strain consolidation theory and large-strain one were made through a great amount of computation and comparison. The large-strain and non-linear rheological consolidation behavior of soft soils was then illustrated.It has been shown that the discrepancy between large-strain consolidation theory and small-strain one is increased with the increases of the compressibility of soil and the magnitude of loading. The self-weight of soil is an important factor affecting consolidation, and once it is taken into consideration, the consolidation becomes quicker and final settlement becomes larger. Rheological property of soft soil contributes to delaying consolidation. The influences such as nonlinear variations of compressibility and permeability, rheological and layered properties of soil,self-weight and time-dependent loading are interacted each other and very complicated, and only they are all taken into consideration, can the consolidation behavior of soft soils be actually revealed.The analytical theory for one-dimensional large-strain and non-linear consolidation of soft soils under time-dependent loading obtained herein provides a direct and efficiency tool for the verification of numerical methods used in solving large-strain consolidation problems. Moreover, the semi-analytical method and the corresponding computer code developed provide more reasonable theoretical supports for practical consolidation analyses and computations of soft clayey soils.