1-D Nonlinear Consolidation Theory And Calculation Of Pore Pressure On Saturated Soft Clay Under Cyclic Loading

The problem of soft clay foundation consolidation under cyclic loading is one of most concerned problems in engineering area, as well as a key subject in academic area. But, for the complexity of soil, consolidation equation analytic solution often can not be obtained easily. Because of the application of computer and the calculation method being improved, studying on that problem has been much more advancement. In this thesis, based on the numerical method, a careful study has been made on one-dimensional consolidation theory of soft clay under cyclic loading with permeability and compressibility varying with time and the pore pressure distribution regularity has also been obtained.Firstly, the paper introduced the form of cyclical loading appeared in engineering, for instance: traffic loading;airplane taking off and landing on airport;wave loading and so on. All of these can be simplified some simple cyclical loading forms presented in this paper. Generalized the study state on dynamic characteristics of soft clay foundation, then, the theory of elastic-plastics constitute and the difference and applicability of total stress method and effective stress method are described.Secondly, based on the universal consolidation equation, leading-in semi-log relation which is nonlinear and more reality(logarithmic relation instead of linear relation), the consolidation differential equation is deduced. With the application of difference method, the nonlinear second-order consolidation differential equation has been solved.Finally, with the tool of Matlab, the consolidation differential equation is solved by computer program. Compared the classical Terzaghi 1-D consolidation equation analytic solution with the numerical solution which solved by the program, the program has been approved to be correct. The elected soft clay foundation mode is single-layer and two-sided drainage. The sinusoidal cyclic loading, semi- sinusoidal cyclic loading, triangular cyclic loading, trapezoidal cyclic loading and rectangular cyclic loading are calculated respectively. By analyzing these calculation results, thelaw of pore water pressure and consolidation degree is obtained.The calculation in this paper has considered nonlinear effect in soft clay deforming, so they must be more credibility and reality.