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The soil water characteristic curve (SWCC) is a graphical relationship between the matric suction (pore water suction) and the water content (gravimeter or volumetric or degree saturation s). It is one of the basic characteristics of unsaturated soils and as such, it is useful for estimating the other properties of soil when solving engineering problems in areas like fluid flow, irrigation scheduling, compressibility and shear strength. SWCC also provide input to the design of a compacted clay cover liner and earth Dam due to its potential impact of flow rate and the dessication processes. Since the experimental procedures, in which a filter paper or pressure plate test adopted for determining the matric suction-water content relationship is time consuming and cost-intensive, hence the need to produce the SWCC using some mathematical functions (models). The fundamental aim of this research is to determine the mechanical behaviour of lateritic soil using SWCC. The soil samples that were used in this research work are residual reddish brown lateritic soil that was obtained from University of Benin Campus. The method of disturbed sampling was employed in obtaining soil samples for laboratory testing. Full laboratory investigation were carried out on the soil samples, these include; liquid limits, plastic limit, plasticity index, liquidity index, specific gravity, particle size analysis and specific gravities. Soil water characteristics curve (SWCC) specimens were prepared with one compactive effort (BSL) to relative OMC. 2.5kg of each specimen was moistened with tap water, mixed thoroughly and compacted in BS moulds and later cored into stainless steel rings with inside diameters of 50mm and heights of 50mm with the aid of a mallet. Each of the 15 specimens was covered with caps at both ends before saturation. The samples were subjected to full saturation by capillary action for a period of 3 weeks. The pressure plate drying test used in this study was conducted to determine the relationships between volumetric water content and matric suction potentials in a soil subjected to pressures ranging between 0 - 1500kPa. Pressure was applied to a predetermined value to induce matric suction. Testing was terminated when the outflow stopped indicating that specimens had equilibrated with the applied matric suction. The specimens were removed and their volumetric water content was determined. The procedure was repeated to develop an entire SWCC by subjecting the soil specimens to different pressures (0 – 1500kPa). In this study, the author used 3 models and they are Van Genuchten equation, Fredlund and Xing equation and Brooks – Corey equation. With the data from the pressure plate extractor to predict hydraulic productivity and volumetric water content of the soil samples. The results of index properties shows that the natural moisture content of the soil is between 36%- 46%, plasticity index is between 17,92% to 28.03%. The specific gravity is between 2.31%-2.57% and the soil is classified as lateritic soil of low plasticity. The SWCC data from pressure plate extractor have been fitted with Van Genuchten (1980); Brooks-Corey (1964); Fredlund and Xing (1994) equation. The result show that the air entry value and residual matric suction for residual soils are in the range of 18kpa to 30kpa and 43kpa to 670kpa respectively.The result shows that: Generally, Van Genuchten and Brooks-Corey models over predicted volumetric water content (θ) at low suctions, while Fredlund-Xing model under predicted it but the values are close to laboratory measured values
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