Studies On One-dimensional Consolidation Theory For Soft Soils With Nonlinear Flow Law

Numerous experiments and settlement measurements have shown that the water flow in soft soils may deviate from Darcy’s law. However, few researches on consolidation theory for soft soils with non-Darcian flow have been reported, especially on non-linear consolidation theory of layed-soil with non-Darcian flow. Therefore, this dissertation systematically studies one-dimensional linear and non-linear consolidation theory with exponential flow law and non-Darcian flow model proposed by Hansbo by finite difference method and semi-analytical method, and one-dimensional consolidation behaviour of soft soils with two common non-Darcian flow models is analyzed in detail. The main original works are as follows:1. Considering time-dependent loading in actual engineering, the differential equations governing one-dimensional consolidation with two common non-Darcian flow models are developed, and the numerical solutions are obtained respectively by finite difference method and semi-analytical method. The consolidation curves obtained by both methods are compared, and the reliability of numerical results is testified. On this basis, the influences of parameters in two common non-Darcian flow models, the thickness of soil layer, the value of external loading and the loading rate on consolidation behavior with non-Darcian flow models are analyzed in detail.2. Considering time-dependent loading and layered distribution of soils in natural foundation, one-dimensional consolidation theory for layered soils with two common non-Darcian flow models is systematically studied. Firstly the problem of one-dimensional consolidation of double-layered soil with two common non-Darcian flow models is solved by finite difference method, and that of multi-layered soils is solved by semi-analytical method. Then consolidation curves of double-layered soil with two common non-Darcian flow models obtained by both numerical methods are plotted together to show the correctness of numerical results. Further more, the influences of parameters of two common non-Darcian flow models, the value of external loading, the total thickness of double-layered soils, relative permeability, relative compressibility and relative thickness of double-layered soils on the consolidation behavior of the double-layered soils are discussed in detail.3. Considering time-dependent loading and different distribution types of self-weight stress and incorporating the nonlinear relationship between void ratio and permeability coefficient as well as that between void ratio and effective stress, the differential equations governing one-dimensional non-linear consolidation with two common non-Darcian flow models are solved by finite difference menthod and semi-analytical method, respectively. The reliability of numerical results is verified by comparing the consolidation curves obtained by both numerical methods. The influence of parameters of non-Darcian flow models, the ratio of compression index to permeability index, the value of external loading, the thickness of soil layer and the distribution type of self-weight stress on nonlinear consolidation behavior with two common non-Darcian flow models are systematically discussed.