The aim of this study was to provide some information about the hydraulic performance of mattresses protecting slopes of low head hydraulic structures. The flow resistance as well as stability of slope were investigated. The experimental programme was conducted in the Chilworth Hydraulics Laboratory, Department of Civil Engineering. Two models were constructed and tested. The inpermeable model (first) had a slope of 1:7 (V;H) with mattress dimensions of 320x350mm and a height of 40mm. The permeable model (second) was built with the same slope except that the mattresses were protecting a sand core. The flow resistance of the mattresses was studied which included Manning's roughness coefficient, Chezy's resistance factor and Darcy-Weisbach friction factor. Velocity distribution above the mattresses was evaluated and found well describing the flow. The stability of the mattresses and their ability to resist failure when exposed to higher discharges were also examined and found stable under the discharges tried. Detailed measurement of pressures were conducted in the permeable model in order to study their effects on the stability of the mattresses; such as; pressure distribution above the mattresses, uplift pressures and seepage forces. Shear stresses due to seepage forces were found very small and could be neglected. Comparison with the results of smooth board simulating a reinforced concrete structure, favours the mattresses as a means to control erosion and dissipate energy efficiently. Measures were suggested in terms of installation to reduce the drag and uplift forces. A design procedure for a slope protected by mattresses was set up and followed by a numerical example implementing the results obtained in this study.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:239540 |
| Date | January 1993 |
| Creators | Tahir, Taha |
| Contributors | Tosswell, Paul |
| Publisher | University of Southampton |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://eprints.soton.ac.uk/414081/ |
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