PHYSICAL MODELLING OF LOCAL SCOUR AROUND BRIDGE PIER
DOI:
https://doi.org/10.11113/mjce.v28.15980Keywords:
Bridge pier, local scour, river with movable bed, physical modelling, model and prototypeAbstract
Accurate estimation of local scour around bridge pier is important for economic and safe design of bridges. Due to the complexity of the phenomenon and weak relationship between laboratory and field data, the conventional method such as laboratory-derived equations may fail in determining the accurate scour depth. In the present study, a new method was developed to determine the temporal variation of scour depth and final scour extension around bridge pier. Accordingly, using the rules of physical modelling for rivers, a simple method was established for physical modelling of local scour around bridge pier. To demonstrate the accuracy of the method, a typical prototype was chosen and the method was applied for determining different dimensions of the model. Based on the sediment density scale, low density sediment with Ïs=1.05 kg/m3 was considered in the model for scour experiment. The results of the experiment including temporal variation of scour depth, equilibrium time and scour depth and final extension of scour hole were then scaled up to the prototype. Finally, empirical equations were utilized to predict maximum scour depth for the typical prototype. Results showed that the value of equilibrium scour depth from the present method was in the range of empirical equations prediction.References
Alabi, P. D. (2006). “Time development of local scour at a bridge pier fitted with a collar.†M.SC
thesis, Civil and Geological Eng. Dept., Univ. of Saskatchewan, Canada.
Blench, T. (1969). Mobile-bed fluviology. University of Alberta Press, Edmonton, Canada.
Chanson, H., (2009). Turbulent air-water flows in hydraulic structures: Dynamic similarity and
scale effects. Environmental Fluid Mechanics, 9(2), 125–142.
Coleman, N. L. (1971). Analyzing laboratory measurements of scour at cylindrical piers in sand
beds. Proc. 14th IAHR Congress, Paris, 3, pp. 307-313.
David S. Mueller, Chad R. Wagner, (2005). Field observations and evaluation of streambed scour
at bridges. Rep. No. FHWA-RD-03-052, Federal Hwy. Administration (FHWA),
Georgetown pike McLean.
Einstein, H. A. (1950). The bed-load function for sediment transportation in open channel flow.
Technical Bulletin No. 1026, U. S. Dep. of Agriculture, Washington, D. C.
Heller, V. (2011). Scale effects in physical hydraulic engineering models. Journal of Hydraulic
Research, 49(3), 293-306.
Jain, S. C. (1981). Maximum clear water scour around circular piers. Journal of Hydraulic
Engineering, 107(5), 611-626.
Johnson, P., (1995). Comparison of pier-scour equations using field data. Journal of hydraulic
engineering, 121(8), 626-629.
Karimaee Tabarestani M. and Zarrati A.R, (2013). Design of stable riprap around aligned and
skewed rectangular bridge piers. Journal of hydraulic engineering, 139(8), 911-91
Kobus H. (1980). Hydraulic modelling. Verlag Paul Parey-Hamburg. Berlin.
Maynord, S. (2006). Evaluation of the micromodel: An extremely small-scale movable bed
model. Journal of Hydraulic Engineering, 132(4), 343–353.
Melville, B. W. and Sutherland, A. J. (1988). Design Method for Local Scour at Bridge Piers.
Journal of Hydraulic Engineering, 114(10), 1210-1226.
Meyer-Peter, E. and Mueller, R. (1948). Formulas for Bed-load transport. IAHR Congress,
Stockholm, Sweden.
Novak P. and Cabelka J. (1981). Models in Hydraulic Engineering, Pitman Advanced Publishing
Program. London.
Novak, P., Guinot, V., Jeffrey, A., Reeve, D., (2010). Hydraulic modelling- an introduction:
Principles, Methods and Applications. Spon Press, London, UK.
Oliveto G. and Hager W.H. (2002). Further Results to Time-Dependent Local Scour at Bridge
Elements. Journal of Hydraulic Engineering, 128(9), 811-820.
Raudkivi A., (1998). Loose boundary hydraulics. A. A. BALKEMA / ROTTERDAM /
BROOKFIELD.
Richardson E. V. and Davis, S. R., (1995). Evaluating Scour at Bridges. 3rd edition Hydraulic
Engineering Circular No.18, Publication No FHWA IP-90-017 U.S. Department of
Transportation, Federal Highway Administration, Washington.
Richardson, E.V., Harrison, Lawrence J., and Davis, Stanley R., (1991). Evaluating Scour at
Bridges. Hydraulic Engineering Circular No. 18, Publication No. FHWA-IP-90-017, Office of
Research and Development, Mclean, Virginia, 105 p.
Shields, I. A., (1936). Application of similarity principles and turbulence research to bed-load
movement. Soil Conservation Service Cooperative Laboratory, California Institute of
Technology Publication No. 167, 44 p.
Waldron R., (2005). “Physical Modelling of Flow and Sediment Transport Using Distorted Scale
Modellingâ€, MS.C thesis, Louisiana State University, USA.
Zokaei, M., Zarrati A. R., Salamatian, S. A., Karimaee Tabarestani, M. (2013). Study on scouring
around bridge piers protected by collar using low density sediment. International Journal of Civil
Engineering, 11(3), 199-205.
