| Summary: | 碩士 === 國立臺灣科技大學 === 營建工程系 === 95 === For many engineering project such as highway, airport or slope engineering, compacted soils are often used. But the degree of saturation of the compacted soils usually lies in between 70%~90% and belongs to unsaturated soil . Additionally, the soil mechanical properties correlates closely with stress state, whereas in the field the soil usually exhibits a complex stress state and stress history. Therefore , stress state needs to be taken into account when considering unsaturated soil properties of the compacted soils.A series of laboratory tests were conducted to determine the complete soil-water characteristic curve of the unsaturated compacted soils. The influence of stress history and soil structure on the soil-water characteristics of the unsaturated compacted lateritic soils were also studied.
The experimental results show that, soil structure of the compacted lateritic soils prepared at different initial water contents is different. Domain structure governs the soil-water characteristics behaviour for the dry-of-optimum compacted lateritic soils. The air-entry value and the degree of saturation of the specimens increase with increasing equivalent pressure, because the pore spaces which are located between the domain of the specimens decrease with the equivalent pressure. Massive structure governs the soil-water characteristics behaviour for the wet-of-optimum compacted lateritic soils. The soil-water characteristics behaviour is not significantly influenced by the equivalent pressure or stress history, the water storage capacity appears to be the same.
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