| Empirical relationships for both permeability and compressibility are evaluated by experimental results. A permeability - void ratio relationship applicable to both sands and clays is presented. Different compressibility relationships are used to fit the experimental results. With the use of the above formulas, it is shown that, for a given soil, the Terzaghi coefficient of consolidation, c(,v), can be directly related to the single variable: effective stress, (sigma). The c(,v) - (sigma) relationship thus developed enables the determination of c(,v) as a continuous function of (sigma). These formulations provide a simple method of experimentally determining c(,v) without the use of conventional time fitting techniques.; The Terzaghi theory makes three major simplifying assumptions with regard to strain magnitude, permeability, and compressibility. Consequently, the Terzaghi theory produces a simple linear governing differential equation of consolidation which can easily be solved by analytical methods. In this study, finite strain governing equations are derived by replacing all the three assumptions mentioned above by more realistic relationships. Small strain nonlinear governing equations are also derived by assuming strain magnitudes are small but using more realistic relationships for permeability and compressibility. The solutions of nonlinear governing differential equations are obtained by numerical methods. The Terzaghi solution and the solutions of small strain theories are evaluated by comparing them with the more accurate finite strain solutions. Analysis is made separately for both instantaneous loading and time-dependent loading. The solutions obtained by small strain nonlinear governing equations always compared very closely with the solution of the Terzaghi linear governing equation. Small strain theories, including the Terzaghi theory, are found to be satisfactory when the strains are not too large, i.e. approximately 30% or less. An evaluation of the standard time fitting techniques of consolidation is also made.; A direct method of calculating the rate of settlement under time-dependent loading is presented. This method does not use a predefined degree of consolidation. Methods of calculating the rate of settlement under nonlinear loading paths as well as staggered loading (i.e. any combination of instantaneous, linear, and nonlinear loading) paths are presented. An experimental study on a large scale consolidometer is also described. |
