Browsing by Author "Ratnajothy, T"

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    item: Conference-Full-text
    Matric suction characteristics of unsaturated residual soils at the Naketiya landslide site
    (2013-11-27) Ratnajothy, T; Puswewala, UGA; Kulathilaka, SAS
    This paper discusses the experimental determination of some matric suction characteristics of residual soils from Naketiya landslide site, Badulla District, Sri Lanka. The test programme required the modification of the triaxial test apparatus using high air entry disks so that pore-air and pore-water pressures of a soil sample could be maintained at required magnitudes. Samples were made from soil obtained from the Naketiya landslide site, and these were tested in triaxial conditions under different matric suction values. The shear strength function and the soil-moisture characteristic curve for the soil are developed. These results are of importance in interpreting the variation of shear strength with the moisture content for the residual soil at Naketiya, which will have a direct bearing on stability of the slopes there.
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    item: Thesis-Abstract
    Matric suction characteristics of unsaturated residual soils of Sri Lanka
    Ratnajothy, T; Puswewala, UGA
    Residual soils from selected prominent landslide sites of the upcountry of Sri Lanka are tested under unsaturated conditions to evaluate pertinent unsaturated properties of the soils. The selected landslide sites are Naketiya, Kahagalla, Walhaputenna and Beragala. The tri-axial test apparatus was modified by using high air-entry disks so that poreair pressures and pore-water pressures of a soil sample could be maintained at separate, required magnitude. Soil samples obtained from Dambulla International Stadium site were used to verify the repeatability of the test results by the modified apparatus, and the reliability of the apparatus. Soil samples obtained from each of the selected landslides sites were prepared at the maximum dry density and optimum moisture content as determined by the proctor compaction test. These were tested in triaxial conditions under five different matric suction (which is the difference between pore-air and pore-water pressure) magnitudes. Time was allowed for each sample to reach an equilibrium state under the particular matric suction applied, before traxial testing commenced. The test results are used to develop the shear strength function for each soil tested, and the soil-water characteristic curve (SWCC) for each soil over the range of matric suction (30 kPa - 200 kPa) considered in the investigation. These results are of importance in interpreting the variation of shear strength with the moisture content for these residual soils, which will have a direct bearing on stability of slopes there.