On the Local Scour Around Group Piers in Series by Experimental Tests

Document Type : Regular Paper

Authors

1 Civil Engineering Department, Engineering Faculty, Shahid Chamran University, Ahvaz, Iran

2 Hydraulic Structure Department, Water Science and Engineering Faculty, Shahid Chamran University, Ahvaz, Iran

3 Civil Engineering Department, Engineering faculty, Shahid Chamran University, Ahvaz, Iran

Abstract

In this article a physical model is presented. A trapezoidal shape of channel with 1.45 m width, 1 meter depth and banks slope of 1H: 1.5V was applied. Circular piers (6, 8 and 10cm diameter) were examined under three dissimilar flow discharges of 50, 65 and 80 lit/s and three different median bed material sizes equal to 0.94, 1.31 and 2.12 mm. Seven different longitude distance to pier diameter ratios (1, 1.5, 2, 2.5, 3, 4 and 5) were examined. Measurement of scour depth (upstream, around and downstream of pier) was accomplished in 10, 15, 20, 30, 60, 120, 240 and 360 minutes from the beginning of each examination. The results indicated that 30%-40%, up to 65% and more than 90% of local scour occurs at first two, 10, 120 and 200 minutes from the beginning of test respectively. The effect of dissimilar parameter especially the distance between piers on scour depth at group piers in series was evaluated and the results were compared to other researchers. It was found that our results is best fitted with the general form of well known Sheppard et al. (2004)’s equation.

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Main Subjects


[1] Laursen, E.M., Toch, A. (1956). “Scour around bridge piers and abutments”. Iowa Highway Research Board Bulletin, No. 4, Iowa City, IA, 60 pp.
[2] Neill, C.R. (1965). “Measurements of bridge scour and bed changes in a flooding sand-bed river”. In: The Institution of Civil Engineers, London, England, 415-435.
[3] Breusers, H.N.C., Nicollet, G., Shen, H.W. (1977). “Local scour around cylindrical piers”.Journal of Hydraulic Research, Vol. 15(3), pp. 211–252.
[4] Hannah, C.R. (1978). “Scour at pile groups”. Rep. No. 28-3,Civil Engineering Department, University of Canterbury, Christchurch, New Zealand
[5] Raudkivi, A.J. (1986). “Functional trends of scour at bridge piers”. Journal of Hydraulic Engineering, ASCE, Vol. 112(1), pp. 1-13.
[6] Raudkivi, A.J. (1997). “Ripples on stream bed”. Journal of Hydraulic Engineering, ASCE, Vol. 123(1), pp. 58-64.
[7] Melville, B.W., Sutherland, A.J. (1988). “Design method for local scour at bridge piers”. Journal of Hydraulic Engineering, ASCE, Vol. 114(10), pp. 1210-1226.
[8] Yanmaz, A.M., Altinbilek, H.D. (1991). “Study of time-dependent local scour around bridge piers”. Journal of Hydraulic Engineering, ASCE, Vol. 117(10), pp. 1247–1268.
[9] Melville, B.W. (1997). “Pier and abutment scour-integrated approach”. Journal of Hydraulic Engineering, ASCE, Vol. 123(2), pp. 125–136.
[10] Hoffmans, G.J.C.M., Verheij, H.J. (1997). “Scour manual”. A.A.  Balkema, Rotterdam, Netherlands, 205 pp.
[11] Ettema, R., Melville, B.W., Barkdoll, B. (1998). “Scale effect in pier-scour experiments”. Journal of Hydraulic Engineering, ASCE, Vol. 124(6), pp. 639-642.
[12] Melville, B.W., Chiew, Y.M. (1999). “Time scale for local scour at bridge piers”.Journal of Hydraulic Engineering, ASCE, Vol. 125(1), pp. 59–65.
[13] Melville, B.W., Coleman, S.E. (2000). “Bridge scour”. Water Resources Publications,Littleton, Colo.
[14] Richardson, E.V., Davis, S.R. (2001). “Evaluating scour at bridges”.Hydraulic Engineering Circular No. 18 (HEC-18), 4th Ed., Rep. No.FHWA NHI 01-001, Federal Highway Administration,Washington, D.C.
[15] Ting, F.C.K., Briaud, J.L., Chen, H.C., Gudavalli, R., Perugu, S., Wei, G. (2001). “Flume tests for scour in clay at circular piers”. Journal of Hydraulic Engineering, ASCE, Vol. 127(11), pp. 969-978.
[16] Sheppard, D.M., Odeh, M., Glasser, T. (2004). “Large scale clear-water local pier scour experiments”. Journal of Hydraulic Engineering, ASCE, Vol. 130(10), pp. 957-963.
[17] Sheppard,, M.ASCE D.M., Jr, W.M. (2006). “Live-bed local pier scour experiments”. Journal of Hydraulic Engineering, ASCE, Vol. 132(7), pp. 635-642.
[18] Simarro, G., Teixeira, L., Cardoso, A.H. (2007). “Flow intensity parameter in pier scour experiments”. Journal of Hydraulic Engineering, ASCE, Vol. 133(11), pp. 1261-1264.
[19] Lu, J.Y., Hong, J.H., Su, C.C., Wang, C.Y., Lai, J.S. (2008). “Field measurements and simulation of bridge scour depth variations during floods”. Journal of Hydraulic Engineering, ASCE, Vol. 134(6), pp. 810- 821.
[20] Zhao, M., Cheng, L., Zang, Z. (2010). “Experimental and numerical investigation of local scour around a submerged vertical circular cylinder in steady currents”. Coastal Engineering, Vol. 57(8), pp. 709-721. 
[21] Salim, M., Jones, J.S. (1996). “Scour around exposed pile foundations”. In: Compilation of Conference Scour Papers (1991–1998),ASCE,Reston, VA
[22] Zhao, G., Sheppard, D.M. (1998). “The effect of flow skew angle on sediment scour near pile groups”. In: Compilation of Conference Scour Papers (1991–1998), ASCE, Reston, VA
[23] Ataie-Ashtiani, B., Beheshti, A.A. (2006). “Experimental investigation of clear-water local scour at pile groups”. Journal of Hydraulic Engineering, ASCE, Vol. 132(10), pp. 1100–1104.
[24] Zounemat-Kermani, M., Beheshti, A.A., Ataie-Ashtiani, B., Sabbagh-Yazdi, S.R. (2009). “Estimation of current-induced scour depth around pile groups using neural network and adaptive neuro-fuzzy inference system”. Applied Soft Computing, Vol. 9(2), pp. 746–755.
[25] Amini, A., Melville, B.W., Ali, T.M., Ghazali, A.H. (2012). “Clear-Water Local Scour around Pile Groups in Shallow-Water Flow”. Journal of Hydraulic Engineering, ASCE, Vol. 138(2), pp. 177-185.
[26] Amini, A., Melville, B.W., Ali, T.M. (2014). “Local scour at piled bridge piers including an examination of the superposition method”. Canadian Journal of Civil Engineering, Vol. 41(5), pp. 461-471.
[27] Moussa, A.M.A. (2018). “Evaluation of local scour around bridge piers for various geometrical shapes using mathematical models”. Ain Shams Engineering Journal, Vol. 9(4), pp. 2571-2580.
[28] Hamidi, A., Siadatmousavi, S.M. (2018). “Numerical simulation of scour and flow field for different arrangements of two piers using SSIIM model”. Ain Shams Engineering Journal, Vol. 9(4), pp. 2415-2426.
[29] Zhang, Q., Zhou, X.L., Wang, J.H. (2017). “Numerical investigation of local scour around three adjacent piles with different arrangements under current”. Ocean Engineering, Vol. 142, pp. 625-638.
[30] Liao, K.W., Muto, Y., Lin, J.Y. (2018). “Scour depth evaluation of a bridge with a complex pier foundation”. KSCE Journal of Civil Engineering, Vol. 22(7), pp. 2241-2255.  
[31] Wang, H., Tang, H., Liu, O., Wang, Y. (2016). “Local scouring around twin bridge piers in open channel flows”.  Journal of Hydraulic Engineering, ASCE, Vol. 142(9), pp. 06016008-1–6016008-8.
[32] Hosseini, R., Amini, A. (2015). “Scour depth estimation methods around pile groups”. KSCE Journal of Civil Engineering, Vol. 19(7), pp. 2144-2156.
[33] Raudkivi, A.J., Ettema, R. (1983). “Clear‐water scour at cylindrical piers”. Journal of Hydraulic Engineering, ASCE, Vol. 109(3), pp. 338-350.
[34] Sheppard, D.M., Zhao, G., Ontowirjo, B. (1995). “Local scour near single piles in steady currents”. In: First International Conference on Water Resources Engineering, American Society of Civil Engineers Conference Proceedings, San Antonio, TX.