Numerical Analysis of the Behaviour of Fluid Infiltrated Soils

Abstract

<p>This thesis deals with numerical modelling of the behaviour of soils infiltrated with fluids. The main objectives are to study the effect of viscosity of the fluid on the response of particulate media under static and dynamic loadings, and to examine the influence of partial saturation on the behaviour under undrained conditions. The latter study is relevant to low as well as high degrees of saturation.</p> <p>In the formulation incorporating the effect of viscous fluid, the effective stress principle is modified by including the shear stress developed in the fluid phase. As this shear stress depends on the rate of shear strains the overall response is rate dependent. The formulation is implemented in a finite element algorithm and a number of numerical examples, including dynamic creep at low and high stress levels, are provided.</p> <p>In the next part of this thesis, the liquefaction of saturated soils is investigated. In these studies the effect of viscosity of liquefied material on the stability of the soil-foundation systems under earthquake excitation is examined. Furthermore, the stability theory is reviewed and a simplified stability criterion is introduced. The problems of stability of a strip foundation and a soil column are analyzed.</p> <p>In the last pan, a mathematical formulation for the behaviour of partially saturated soils is implemented in the finite element algorithm and some boundary-value problems are solved. In order to examine the performance of the constitutive model, a series of experimental tests are carried out. Subsequently, the effect of partial saturation on the stability of soil-foundation systems is examined. The liquefaction phenomenon under earthquake loading is studied for the case of high degrees of saturation, while the bearing capacity of fine grained soils is analyzed for the case of low degrees of saturation.</p>