TRB"s National Cooperative Highway Research Program (NCHRP) Report 653: Effects of Debris on Bridge Pier Scour explores guidelines to help estimate the quantity of accumulated, flow event debris, based on the density and type of woody vegetation and river bank condition upstream and analytical procedures to quantify the effects of resulting debris-induced scour on bridge piers. The debris photographic archive, the survey questionnaire and list of respondents, and the report on the field pilot study related to development of NCHRP 653 was published as NCHRP Web-Only Document 148: Debris Photographic Archive and Supplemental Materials for NCHRP Report 653.
|Statement||P.F. Lagasse ... [et al.].|
|Series||NCHRP report -- 653|
|Contributions||National Research Council (U.S.). Transportation Research Board, National Cooperative Highway Research Program, American Association of State Highway and Transportation Officials, United States. Federal Highway Administration|
|LC Classifications||TG320 .E34 2010|
|The Physical Object|
|Pagination||115,  p. :|
|Number of Pages||115|
|LC Control Number||2010926176|
TRB's National Cooperative Highway Research Program (NCHRP) Report Effects of Debris on Bridge Pier Scour explores guidelines to help estimate the quantity of accumulated, flow event debris, based on the density and type of woody vegetation and river bank condition upstream and analytical procedures to quantify the effects of resulting debris-induced scour on bridge piers. PDF | Scour is one of the most recurrent causes of failure of bridge structures in alluvial rivers. There is a variety of formulas for the assessment of | Find, read and cite all the research. Debris placed on the bottom, upstream of the bridge pier, with a triangular shape, does not induce any increase in scour depths, the values are practically the same as the one obtained for the reference pier (without debris); ii) The method suggested by , as modified by , performed well, replicating the main trends observed in the. An experimental study on the bridge pier clear-water scour evolution in the presence of wood debris was conducted at the PITLAB research centre, University of Pisa, Italy. A debris accumulation is characterized by roughness, shape and porosity. Flow intensities range from 65 to %.
Waterborne debris (or drift) often accumulates on bridges during flood events. The effects can vary from minor flow constrictions to severe flow contraction resulting in significant bridge. Large wood debris transported by floods affects the scour morphology at bridge piers, thus increasing the bridge failure potential. The characteristic size and shape of the riparian vegetation includes various roughness and permeability conditions of the debris surface. The interaction between two-dimensional flow and rough debris accumulations increases the shear stress, the turbulence and. The accumulation of large wood debris around bridge piers obstructs the flow, producing increased upstream water levels, large horizontal structural loadings, and flow field modifications that can considerably exacerbate scour. These effects have frequently been held responsible for the failure of a large number of bridges around the world, as. Debris accumulation on bridge piers is an on-going national problem that can obstruct the waterway openings at bridges and result in significant erosion of stream banks and scour at abutments and piers. In some cases, the accumulation of debris can adversely affect the operation of the waterway opening or cause failure of the structure.
Previous experimental research on the effects of debris on pier scour has focused primarily on circular and rectangular piers with debris present just under flow free surface. Debris-induced scour around sharp-nose piers, which are typical of masonry bridge piers, and the effect of debris elevation on pier scour have seldom been studied before. Debris accumulation at bridge pier effects to bridge pier scour has been studied by several researchers. But the effects of debris accumulation at sacrificial piles on bridge pier scour have not. Large woody debris (LWD) reduces the flow area, deviate the flow and increases the velocity in correspondence of the bridge pier, therefore increases the maximum scour hole depth and accelerates sediment removal. Logs and drifts accumulated on bridge piers are of different dimensions. A novel method for evaluating the effect of debris accumulation on local scour depth at bridge piers is introduced. The concept of a ‘debris factor’ is proposed to replace the current effective and equivalent pier width approaches that have been shown to overestimate debris-induced scour .