Study On Finite Strain Consolidation Theory Under Osmotic Pressure

This thesis focused on the warping soil consolidation mechanism under osmotic pressure as to blanket cracks disposal in earth dam.Based on the consolidation mechanism analysis of the warping clay under osmotic pressure, a finite strain osmotic pressure consolidation equation, of which the excess pore-pressure or void ratio was selected as dependent variable, was derived. The non-linear relationships between the void ratio and effective stress as well as between the permeability coefficient and the void ratio were taking into account during the theoretical derivation. This kind of consolidation was induced by body face, which was different from the existed consolidation induced by surface load.The osmotic pressure test was developed to determine the unknown, finite strain consolidation coefficient and convection coefficient in the mathematical model. The two coefficients both varied with effective stress and depth and were functions of initial void ratio, compressibility, permeability and permeability derivative along depth.A precise time step integration method was proposed to solve the finite strain osmotic consolidation equation with varied coefficients. The corresponding programs in matlab language were presented for various operating mode computations. Thus, the excess pore-pressure and void ratio distribution along space-time could be derived. The degree of consolidation, which could be expressed by excess pore-pressure or deformation, was derived for various operating mode and its' characteristics along space-time showed rules of warping soil consolidation under osmotic pressure. An analytic solution expression of osmotic consolidation differential equation was derived under certain condition.A model test was designed to simulate the consolidation process of warping soil, the validity of theoretical equation and the solution methods presented in this study. Actual measurements for excess pore-pressure, void ratio and settlement-time curves all showed good agreement with the corresponding computed values.