South Atlantic Water Science Center
South Atlantic Water Science Center
Project Number: MK00E19
Project Chief: Stephen Benedict
Period of Project: October 1, 2012 to December 31, 2014
Cooperator: National Cooperative Highway Research Program
National Cooperative Highway Research Program
THIS PROJECT HAS BEEN COMPLETED AND IS BEING ARCHIVED IN ITS FINAL CONFIGURATION
The National Cooperative Highway Research Program (NCHRP) has recently sponsored several projects for the development of new abutment-scour prediction methods for cohesive and non-cohesive soils.
These projects include:
With the completion of these projects there is need to test the newly-derived laboratory methods using field data, in order to identify strengths, weaknesses, and limitations and provide guidance to the practitioner for the application of these methods.
The primary objective of this investigation is to test the abutment-scour prediction methods developed in the NCHRP Projects 24-15(2) and 24-20 (Briaud and others, 2009; Ettema and others, 2010, respectively), using U. S. Geological Survey (USGS) field data. The USGS field data include 209 measurements in South Carolina (Benedict, 2003), 29 measurements in the USGS National Bridge Scour Database (NBSD; USGS, 2001; Wagner and others, 2006), 100 measurements in Maine (Lombard and Hodgkins, 2008), and 37 measurements in Alabama (Lee and Hedgecock, 2008) (Figure 1). (Note: The Alabama data were originally classified as clear-water contraction scour. However, field conditions at some of these sites were comparable to abutment scour at short bridges with large contractions of flow and therefore, were used in this investigation.) The USGS abutment-scour field data primarily represents scour associated with clear-water scour conditions. Therefore, findings in this investigation will be limited to this type of scour.
Using approaches similar to Benedict and others (2006; 2007; figure 2) and Lombard and Hodgkins (2008) the USGS will test the performance of the abutment-scour prediction methods developed in the NCHRP Projects 24-15(2) and 24-20, using selected USGS field measurements of abutment scour (table 1).
Figure 2. Example graphs showing the relation of predicted and observed abutment scour for selected abutment-scour equations using field data (from Benedict and others, 2007).
Table 1 Range of selected variables for abutment-scour measurements used in this investigation.
This investigation will benefit the NCHRP and engineering practitioner by evaluating the field performance of the abutment-scour prediction methods developed in the NCHRP Projects 24-15(2) and 24-20. This evaluation will help identify strengths, weaknesses, and limitations of these scour-prediction methods. The results of the analysis will provide guidance to the practitioner regarding the application and limitations of these methods.
The findings will be documented in a NCHRP report that will be released at the end of the project under the direction of the NCHRP.
Benedict, S.T., 2003, Clear-water abutment and contraction scour in the Coastal Plain and Piedmont Provinces of South Carolina, 1996-99: U.S. Geological Survey Water Resources Investigation Report 03-4064, 137 p.
Benedict, S.T., Deshpande, N., and Aziz, N.M., 2007, Evaluation of abutment scour prediction equations with field data:Washington, D.C., Transportation Research Board of the National Academies, Transportation Research Record, v. 2025, p. 118-126.
Benedict, S.T., Deshpande, N., Aziz, N.M., and Conrads, P.A., 2006, Trends of abutment-scour prediction equations applied to 144 field sites in South Carolina: U.S. Geological Survey Open-File Report 2003–295, 150 p.
Briaud, J.-L., Chen, H.-C., Chang, K.-A., Oh, S.J., and Chen, X., 2009, Abutment scour in cohesive materials: National Cooperative Highway Research Program, Transportation Research Board, Washington, D.C., 435 p.
Ettema, R., Nakato, T., and Muste, N., 2010, Estimation of scour depth at bridge abutments: National Cooperative Highway Research Program, Transportation Research Board, Washington, D.C., 436 p.
Lee, K.G., and Hedgecock, T.S., 2008, Clear-water contraction scour at selected bridge sites in the Black Prairie Belt of the Coastal Plain in Alabama: U.S. Geological Survey Scientific Investigations Report 2007–5260, 57 p.
Lombard, P.J., and Hodgkins, G.A., 2008, Comparison of observed and predicted abutment scour at selected bridges in Maine: U.S. Geological Survey Scientific Investigations Report 2008–5099, 23 p.
Wagner, C.R., Mueller, D.S., Parola, A.C., Hagerty, D.J., and Benedict, S.T., 2006, Scour at contracted bridges: Transportation Research Board, National Cooperative Highway Research Program Document 83 (Project 24-14), 299 p., accessed December 19, 2008, at http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_w83.pdf
U.S. Geological Survey, 2001, National bridge scour database: Accessed July 22, 2011, at https://water.usgs.gov/osw/techniques/bs/BSDMS/index.html.