Research Of Consolidation Model And Calculation Theory Based On The Transformation Rules From Micropore Characteristics Of Soft Soil

The nonlinear consolidation and compression is one of the inherent complex properties of soft soil. After more than 60 years’ development, the nonlinear consolidation theory has made abundant achievements. But most of them research on infiltration and consolidation traits of soft soil from a macro standpoint, it is very difficult to select nonlinear consolidation model and the model of coefficient of consolidation of soft soil and determine the parameters of them, which puzzles the practical application and development of the consolidation theory in the engineering of soft clay. Based on the full understanding of the soft soil microstructure variation rule influencing the consolidation characteristics,it is an important and urgent work to establish consolidation model which can reflect the actual stress and consolidation deformation of soft soil and realize numerical analysis and application in geotechnical engineering practice. Through indoor test and theoretical analysis, this paper in-depthly research on consolidation model and the calculation theory of soft soil. The main contents include:First, summary and analysis microstructure characteristics of soft soil and research results of engineering properties at home and abroad, introduce the exploration and the scope of application about consolidation model of soft soil.Second, treat remolded soft soil in the Pearl River Delta as the research object, conduct consolidation test and permeability test.Based on the test results,summarize the nonlinear consolidation model and the coefficient of consolidation model applicable to normal consolidated soft soil in the Pearl River Delta. The coefficient of consolidation of soft soil consolidation model is composed of natural parts and consolidation change parts,The latter can be expressed as the relationship with consolidation pressure.Third, Based on the e-lnp model and large strain condition,combine soil element equilibrium equation and geometric deformation equation with seepage continuous equation.build the one-dimensional nonlinear consolidation model and the calculation model of the coefficient of consolidation applicable to soft soil,then expand one-dimensional consolidation equation to consolidation model of two-dimensional, three-dimensional condition.Consolidation model based on variation rule of micro-void characteristics of soft soil is satisfied with deformation compatibility condition.Fourth, use implicit finite-difference scheme for solving one-dimensional consolidation equation,use alternating direction implicit method for solving two-dimensional consolidation equation, axisymmetric consolidation equation and three-dimensional consolidation equation.use Matlab for working out difference method solving program,the numerical solution from difference method solving program is in good agreement with Terzaghi one-dimensional consolidation exact solution and Terzaghi-Rendulic consolidation equation exact solution,verify the validity and accuracy of the difference scheme.Fifth, carry out theoretical calculation for one-dimensional consolidation condition, two-dimensional consolidation condition, double-layered ground and vertical drain problems. The numerical results show that: dissipation rate of excess pore water pressure of consolidation model based on variation rule of micro-void characteristics of soft soil is significantly slower than Terzaghi consolidation model,Terzaghi-Rendulic consolidation equation and Biot consolidation model’s, the coefficient of consolidation of which are a constant, and correctly reflect dissipation process of monolayer and multilayer foundation pore water in the one-dimensional or multi-dimensional case. Compared with consolidation test data of soft soil, WG model more accord with the real situation of consolidation theory.