Evaluation of Hydro-Mechanical Behaviour of Hydraulic Barriers of Landfill Covers
Bentonite amended local soils are used as hydraulic barriers (CB) in municipal solid waste landfills and for the disposal of low level radioactive waste stored containers. Excessive settlements can cause cracks in the CB which affect the strength and provide preferential flow paths to fluids compromising the sealing efficiency of the barrier. Thus, the integrity of CB with respect to their hydraulic conductivity and flexural strength is very important to prevent the environment hazards. In the present study, a series of hydraulic conductivity tests, direct tensile tests and centrifuge model tests were conducted on model barriers. The influence of waste settlement on the long term performance of the barriers was studied by conducting a series of centrifuge model tests. Digital Image Cross-Correlation technique was used in the present study for obtaining the tensile strain in the barrier during settlement. Since, clay is having low tensile strength and low tensile strain at failure, an attempt was made to improve its tensile strength by using polyester discrete geofibers. A custom designed direct tensile test set-up was used to evaluate the tensile strength-strain characteristics of the unreinforced CB and fiber reinforced soil barriers (FB). A flexible wall permeameter was used in the present study for studying the influence of geofibers on the hydraulic conductivity of the barriers. From the present study, it was observed that for the type of fibers, fiber dosage and length and soil used in the present study, the tensile strain at failure was increased to a maximum of 2.5 times and hydraulic conductivity of the soil has not varied drastically and satisfied target hydraulic conductivity requirements for the hydraulic barriers of the landfills.
KeywordsLandfills MSW settlements Tensile tests Flexible wall permeameter Centrifuge modelling
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