Failure of Riprap Protection (Phase I)

Failure of riprap protection systems in culvert outlets and rundowns has been identified by the New Mexico Department of Transportation (NMDOT) Drainage Section staff as a frequent problem in some areas of New Mexico. The poor performance of the riprap protection at given sites has required recurrent costly maintenance repairs. In this study, a preliminary investigation of the most likely causes of the riprap failure in Southern New Mexico was performed, focusing on the design guidelines and performance of riprap for culvert outlets. Selected locations were visited with the purpose of identifying the possible mechanisms of failure of the riprap at culvert outlets. The field observations indicate that the majority of the sites visited have undergone significant erosion and scour. The riprap was completely missing in a number of locations and the failure can be mainly attributed to a combination of local scour and general channel degradation. This scour is partially due to high exit velocities and highly erodible soils. The installation of block energy dissipators is proposed to dissipate the necessary energy to re-establish the channel conditions downstream of the structure in a relatively short distance. Concrete or gabion blocks on a riprap basin are suggested as dissipators for small- and medium-size culverts. Because the dimensioning of the energy dissipators recommended here is based on empirical equations from previous experimental studies, field trial tests and monitoring are strongly recommended as future work to corroborate the efficiency of the proposed solution.

  • Corporate Authors:

    New Mexico State University, Las Cruces

    Department of Civil Engineering, P.O. Box 30001
    Las Cruces, NM  United States  88003-8001

    New Mexico Department of Transportation

    Research Bureau, 7500B Pan American Freeway, P.O. Box 94690
    Albuquerque, NM  United States  87199-4690

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Bandini, Paola
    • White, Kenneth R
  • Publication Date: 2006-3

Language

  • English

Media Info

  • Media Type: Print
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 24p

Subject/Index Terms

Filing Info

  • Accession Number: 01044271
  • Record Type: Publication
  • Report/Paper Numbers: NM04STR-04
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Mar 4 2007 2:14PM