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T Thyagaraj
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T Thyagaraj
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T Thyagaraj
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Thyagaraj, T.
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4 results
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- PublicationInfluence of osmotic suction on the soil-water characteristic curves of compacted expansive clay(01-05-2010)
; Rao, Sudhakar M.Unsaturated clays are subject to osmotic suction gradients in geoenvironmental engineering applications and it therefore becomes important to understand the effect of these chemical concentration gradients on soil-water characteristic curves (SWCCs). This paper brings out the influence of induced osmotic suction gradient on the wetting SWCCs of compacted clay specimens inundated with sodium chloride solutions/distilled water at vertical stress of 6.25 kPa in oedometer cells. The experimental results illustrate that variations in initial osmotic suction difference induce different magnitudes of osmotic induced consolidation and osmotic consolidation strains thereby impacting the wetting SWCCs and equilibrium water contents of identically compacted clay specimens. Osmotic suction induced by chemical concentration gradients between reservoir salt solution and soil-water can be treated as an equivalent net stress component, (pπ) that decreases the swelling strains of unsaturated specimens from reduction in microstructural and macrostructural swelling components. The direction of osmotic flow affects the matric SWCCs. Unsaturated specimens experiencing osmotic induced consolidation and osmotic consolidation develop lower equilibrium water content than specimens experiencing osmotic swelling during the wetting path. The findings of the study illustrate the need to incorporate the influence of osmotic suction in determination of the matric SWCCs. © 2010 ASCE. - PublicationEffect of pore fluid osmotic suction on matric and total suctions of compacted clay(01-11-2015)
; Salini, U.The experimental results of the present study on compacted expansive clay illustrate that matric suction increases with the increase in pore fluid osmotic suction due to changes in soil structure. Scanning electron micrographs show that particle stacking (aggregations) increases with increase in pore fluid osmotic suction and cation valence due to reduction in diffuse double layer thickness, and thus results in a reduction in micro pore size with a corresponding increase in macro pore size. At a given water content, the macro pore degree of saturation reduces with the increase in osmotic suction owing to the increase in macro pore size and leads to an increase in matric suction, as the matric suction is characteristic of the macro pore and the degree of saturation of the macro pore. The matric, osmotic and total suction measurements using the filter paper method also confirm that the matric and osmotic suction components are additive. This demonstrates that the method of obtaining matric suction from the difference between total suction and pore fluid osmotic suction determined using non-contact filter papers is reliable. - PublicationEffect of pore fluid and wet-dry cycles on structure and hydraulic conductivity of clay(01-01-2019)
; Julina, M.Compacted clays in landfill applications are subjected to both physico-chemical changes and wet–dry cycles. Physico-chemical interactions occur at the microstructural level between the clay particles and chemical constituents such as brine solutions or leachates generated from landfill waste. Furthermore, the volumetric changes during wetting and drying also cause microstructural changes to compacted clays. The microstructural changes due to the physico-chemical interactions and wet–dry cycles are reflected at the macrostructural level and govern the macro-behaviour of compacted clays. Therefore, this paper brings out the combined effect of the interacting fluid and wet–dry cycles on volume change, microstructure and hydraulic conductivity of compacted clay soil. To achieve this, the compacted clay specimens were inundated with distilled water and sodium chloride (NaCl) solutions during wetting cycles. The experimental results showed that the ability of clay particles to swell at microstructural level and decrease the size of macropores in compacted clay was completely lost with 4 M sodium chloride solution and with increase in wet–dry cycles. Thus, the hydraulic conductivity of compacted clay specimen inundated with 4 M sodium chloride solution was unusually high at the end of the second and further wetting cycles even when subjected to higher effective confining pressures. - PublicationPhysico-chemical effects on shrinkage behavior of compacted expansive clay(01-02-2017)
; ;Thomas, Sona RachelDas, Amiya PrakashPhysico-chemical effects have a significant impact on the behavior of clay barriers due to the interactions between the pore fluid and clay particles, and they pose a great challenge because the efficiency of clay barriers and cover systems may be altered. Therefore, this paper highlights the effect of physico-chemical factors on shrinkage behavior of compacted expansive clay. To achieve this, the compacted clay specimens were inundated with distilled water, NaCl, and CaCl2 salt solutions in separate oedometer cells at a vertical pressure of 6.25 kPa and allowed to swell. The swollen specimens were gradually shrunk until the specimens attained constant mass, and the changes in void ratio and water content were monitored during drying. The experimental results showed that magnitude of induced osmotic suction and type of pore fluid had a significant impact on shrinkage behavior of compacted clay specimens due to the changes in soil structure. The average pore size of compacted specimens significantly decreased with the induced osmotic suction due to the reduction in size of micropores owing to the suppression of double layers. The discussions are supported by scanning electron microscopy images. Also, the experimental shrinkage data were fitted using modified van Genuchten and Fermi mathematical models, and the results showed that these models fit well with an adjusted R2 higher than 0.9962.