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Experimental Study of Geotextile's Drainage and Filtration Properties in Dams under Different Hydraulic Gradients and Boundary Conditions

Zahmatkesh, Zahra | 2008

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39329 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Pak, Ali
  7. Abstract:
  8. Geotextiles are one of the most widely used materials in filtration and drainage applications. Since geotextiles are exposed to different stresses and hydraulic gradients, thier hydraulic behavior in real situations is of great importance. In this study, filtration and drainage of several nonwoven needle-punched geotextiles with different properties and unit masses per area of 200g/m2, 400g/m2, 500g/m2 and 800g/m2 under various confined stresses and hydraulic gradients are investigated. To get to these aims, permittivity and transmissivity apparatuses were designed and built in the course of this investigation. Then samples which were emerged for at least 24 hours were tested under different confined stresses and hydraulic gradients. Normal stresses varied between 0 to 1000kPa, depending on the type of the tests. Hydraulic gradients in transmissivity tests were 0.5, 1, and 3 and constant head in the permittivity tests was changed in the range of 10cm to 60cm. In this work, the effect of increasing the number of layers on permeability was also investigated. It was seen that the transmissivity decreases exponentially with increasing the normal stress down to a residual value. The results also show that with increasing the hydraulic gradient, both transmissivity and permittivity decrease. The Geotextile hydraulic behavior is of great usage in the design of landfill covers; design of embankments and irrigation structure drainage systems, and in the design of protection systems in river engineering
  9. Keywords:
  10. Drainage ; Filtration ; Normal Stress ; Geotextile ; Hydraulic Gradient

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