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UBC Theses and Dissertations

A new method to correct void ratio for expansive soil Nunes Muniz Barreto, Priscila


Expansive soil undergoes significant volume variations due to changes in soil water content. Understanding this problematic soil is key for an effective design of landfill layers, dams, pavements, and other structures on this type of soil. Not much has been discussed about the effect of soil expansion on the calculation of soil void ratio, which is the space between soil grains. Increase in moisture occupying the soil voids causes water infiltration in to the space between adjacent clay layers leading to increase in the mineral d-spacing and consequently the volume of the clay particle. Therefore, the global soil void ratio, in the case of expansible soil, is composed of the effective space between grains and the space occupied by the water in the interlayer space. This research proposes a new method to calculate an effective void ratio for expansible soil which is calculated after deducting the interlayer water from the global void ratio. This new method differs from others previously put forth because it can be applied to all expansible soils. The effective void ratio concept is developed using soil-water characteristic curves, where the void ratio is a key parameter. Also, the effect of time on particle hydration was evaluated via hydrometer and laser diffraction tests. The experimental results indicated that the volume of the clay particles increased, which was observed to be due to change in the specific gravity of the expansible soil. The void ratio and water content were corrected, and the conclusion is that the interlayer water should be considered separately for expansible soil even for a soil composed of small amounts of expansible minerals.

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