Flow through filters in embankment dams

This thesis presents studies relating to filter and filtration problems, namely time-dependent filtration process of a given combination of base and filter soils, suffusion mechanism of filters, and determination of saturated hydraulic conductivity of filters. Firstly, the time-dependent filtration process was studied by incorporating superior tools related to the pore network of filters, hydraulic behaviour, and the transport of soil particles. The outcome of this model can be used to evaluate the effectiveness of filters through the accumulation of base soils within filter layers, or the flow rate that describes the stable formation of the self-filtering layer within filters, or unstable layers. Secondly, a new method was proposed to consider the bimodal structure of suffusion soils that have not been appropriately assessed in the past. A procedure to determine a particle size called 'delimiting particle size' was introduced to consider the porosities of finer and coarser fractions of suffusion soils. Furthermore, the concept of constriction sizes was applied to this study, leading to a criterion for assessing whether or not a given soil possesses the potential for suffusion. Finally, a new equation for determining the saturated hydraulic conductivity of granular soils was proposed to correlate the hydraulic conductivity and pore network of soils that can be presented by constriction sizes. Unlike past studies that related hydraulic conductivity to particle sizes, the new constriction based method shows more proper predictions than existing approaches using particle sizes.