Numerical modeling of local scour of non-uniform graded sediment for two arrangements of pile groups  

作　　者：Saeid Okhravi Saeed Gohari Mahdi Alemi Rodrigo Maia 

机构地区：[1]Institute of Hydrology,Slovak Academy of Sciences,Dúbravska Cesta 9,84104,Bratislava,Slovak Republic [2]Department of Water Engineering,College of Agriculture,Bu-Ali Sina University,65178-38695,Hamadan,Iran [3]Departamento de Engenharia Civil,Faculdadede Engenharia,Universidade do Porto,Rua Dr.Roberto Frias,Porto 4200-465,Portugal [4]CIIMAR-Interdisciplinary Centre of Marine and Environmental Research,University of Porto,Terminal de Cruzeiros do Porto de Leixoes,Avenida General Norton de Matos,4450-208,Matosinhos,Portugal

出　　处：《International Journal of Sediment Research》2023年第4期597-614,共18页国际泥沙研究（英文版）

基　　金：support of the Faculty of Engineering,Department of Civil Engineering,of the University of Porto。

摘　　要：A three-dimensional(3D)non-hydrostatic numerical model is established to investigate local scour around four aligned circular piles in uniform and non-uniform sediment mixtures and to provide information for improving scour countermeasures design.In the current study,unsteady Reynolds averaged Navier-Stokes(URANS)equations along with a Re-normalization Group(RNG)k-εmodel were applied to simulate the flow field.A non-uniform sediment transport model was applied to estimate the bedload transport.The simulations lasted up to 8 h.The laboratory results of a reference single pile case in uniform and non-uniform sediment were utilized to validate the simulation results of bed elevation changes and time evolution of scour depth and reflected a good agreement.The influence of pile spacing for two arrangements of pile groups,one column(tandem)and two columns(nontandem)of four aligned piles,on spatial/temporal variations of the bed surface in both sediment bed configurations are discussed in detail.The results reveal the significant effects of the pile spacing on the flow field and patterns of scour hole formation and sediment deposition.In general,lower pile spacing results in more scour upstream of the front pile(s)and shifts deposition more downstream due to the existence of higher energy in the wake region of the piles for both sediment types.Side scouring dominates for non-uniform sediment around each pile due to flow deviating because of the presence of relatively larger particles in front of the pile(s).For non-uniform sediment,deposition begins to develop at the exit area of the scour hole and enhances boundary resistance to scour.The knowledge gained from this study is suitable for the accurate determination of riprap dimensions around the front pile(s)and rear piles in a pile group.

关 键 词：Local bridge pier scour Non-uniform sediment Numerical modeling Pile groups Pile spacing Sediment transport 

分 类 号：U442.32[建筑科学—桥梁与隧道工程]