Surface treatment and scour protection adjacent to culvert and bridge waterways

It is assumed that the major cause of erosion is turbulence. The size of the eddy is approximately that of the generating boundary and the number of eddies per unit time, a function of the velocity. The amount of energy is a function of power of the diameter. Thus a big eddy has a lot more energy than little eddies. Also big eddies persist for a longer time. 'Once an eddy always an eddy' so the only way to get rid of large turbulence is to break it down into a lot of little eddies which can do no harm. Provided the initial turbulence is not large enough to pull out large chunks of soil, grass offers the best protection. It is completely effective at the highest velocities we have been able to direct at it, 5-6 m/sec. Even with a 50 per cent cover. The large turbulence can be avoided by designing smooth shapes, but the risk during grass establishment or the effect of drought has been countered by the use of a plastic mesh set on small gravel. (A).

Language

  • English

Subject/Index Terms

Filing Info

  • Accession Number: 01439636
  • Record Type: Publication
  • Source Agency: ARRB
  • ISBN: 0869102338
  • Files: ATRI
  • Created Date: Aug 24 2012 10:26PM