scholarly journals Reduction of local scouring at round-nosed rectangular piers using a downstream bed sill

2021 ◽  
Vol 63 (3) ◽  
pp. 1-9
Author(s):  
E Sanadgol ◽  
M Heidarpour ◽  
R Mohammadpour
Keyword(s):  
Laboratory Experiments ◽  
Local Scour ◽  
Maximum Efficiency ◽  
Width Ratio ◽  
Scour Depth

This study investigated the effectiveness of bed sills in reducing the scour depth with time at rectangular piers in a laboratory. Experiments were conducted just below the threshold of sediment motion (U/Uc = 0.95) for round-nosed piers with the length-to-width ratios of L/b = 1, 2, 3 and 4. Accordingly, a 1 cm thick PVC section as wide as the channel was used as the bed sill, which was flush with the bed and located at various distances, D, in the downstream of the piers, i.e. D/b = 0, 1, 2 and 3. It was found that the efficiency of the bed sill for a rectangular pier was significantly less than that for the circular one; there was a decrease in efficiency and scour depth with an increase of the pier length. The maximum efficiency obtained for the round-nosed piers with L/b = 1, 2, 3 and 4 was 32.5%, 21.3%, 14.4% and 5.7%, respectively. The application of a bed sill to reduce the local scour in round-nosed rectangular piers, when the length-to-width ratio exceeds 2, is therefore not recommended. Furthermore, the efficiency of the bed sill is the best when it is attached to the downstream end of the pier; its efficiency is decreased when increasing its distance from the pier.

Three-dimensional numerical simulation of local scour in the vicinity of circular side-by-side bridge piers with ice cover

2020 ◽  
Author(s):  
Mohammad Reza Namaee ◽  
Jueyi Sui ◽  
Yongsheng Wu ◽  
Natalie Linklater
Keyword(s):  
Laboratory Experiments ◽  
Transport Model ◽  
Numerical Models ◽  
Three Dimensional ◽  
Ice Cover ◽  
Local Scour ◽  
Bridge Piers ◽  
Accurate Estimation ◽  
Scour Depth ◽  
Cold Regions

Local scour around piers is one of the primary causes of collapse of bridges that cross rivers. The most severe scouring occurs in cold regions where ice cover significantly changes the velocity profile. Having an accurate estimation of the maximum scour depth around bridge piers, especially in cold regions, is necessary for a safer design of piers. In this study, 3-D numerical models are compared to laboratory experiments to examine the process of local scour around bridge piers with and without smooth and rough ice cover. By using the equation of Meyer-Peter Müller, the sediment transport model is validated to approximate the transport of the sediment particles. Numerical results showed good agreements with experimental observations where the maximum scour depth and Turbulent Kinetic Energy (TKE) around bridge piers were the highest under rough ice cover conditions.

Experimental Investigation of Local Scour Around a Submerged Vertical Circular Cylinder in Steady Currents

2009 ◽  
Author(s):  
Ming Zhao ◽  
Liang Cheng ◽  
Zhipeng Zang
Keyword(s):  
Experimental Investigation ◽  
Circular Cylinder ◽  
Laboratory Experiments ◽  
Three Dimensional ◽  
Development Rate ◽  
Local Scour ◽  
Scour Depth ◽  
Sediment Size ◽  
Seabed Topography ◽  
Bed Scour

Local scour around a submerged vertical circular cylinder in steady currents was studied by laboratory experiments. The experiments were conducted under live-bed scour conditions. Only one median sediment size of d50 = 0.40 mm was used in the experiments with a uniformity parameter of d85/d15 = 1.42. In some of the tests, time-developments of scour depth at the stagnation point of the cylinder were measured using the conductivity scour probes. Three-dimensional (3D) seabed topography around each model cylinder was measured using a laser profiler developed at University of Western Australia. The experimental results showed that the scour depth increased with an increase in cylinder height. The development rate of scour depth increases if Shields parameter increases.

scholarly journals Impact Assessment of Pier Shape and Modifications on Scouring around Bridge Pier

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1761 ◽  
Author(s):  
Rashid Farooq ◽  
Abdul Razzaq Ghumman
Keyword(s):  
Experimental Study ◽  
Impact Assessment ◽  
Experimental Research ◽  
Vortex Formation ◽  
Local Scour ◽  
Bridge Pier ◽  
Width Ratio ◽  
Scour Depth ◽  
Length Width

Previous experimental research on utilizing pier modifications as countermeasures against local scour has focused primarily on circular pier. It is of utmost importance to further investigate the most suitable pier shape for pier modification countermeasure separately and in combination. This experimental study aims to reduce the stagnation of the flow and vortex formation in front of the bridge pier by providing a collar, a hooked collar, a cable, and openings separately and in combination around a suitable pier shape. Therefore, six different pier shapes were utilized to find out the influence of pier shape on local scouring for a length–width ratio smaller than or equal to 3. A plain octagonal shape was shown as having more satisfactory results in reducing scour compared to other pier shapes. Furthermore, the efficiency of pier modification was then evaluated by testing different combinations of collar, hooked collar, cable, and openings within the octagonal bridge pier, which was compared to an unprotected octagonal pier without any modification. The results show that by applying such modifications, the scour depth reduced significantly. The best combination was found to be a hooked collar with cable and openings around an octagonal pier. It was revealed that the best combination reduced almost 53% of scour depth, as compared to an unprotected octagonal pier.

scholarly journals Study of the Local Scour Around L-Shape Groynes in Clear Water Conditions

2018 ◽  
Vol 7 (4.20) ◽  
pp. 271
Author(s):  
Saleh I. Khassaf ◽  
Hiba A. Abbas
Keyword(s):  
Laboratory Experiments ◽  
Local Scour ◽  
Design Stage ◽  
Scour Depth ◽  
Clear Water ◽  
Flow Area ◽  
Training Structures ◽  
River Training ◽  
New Formula ◽  
Good Agreement

River training structures; such as groynes; are efficient engineered methods utilized to protect eroding river banks. But during groynes design stage; the designers faces one of the most significant issues which is the evaluation of the maximum depth of local scour around groynes. This is due to the flow area constriction in the groyne location itself; which in turn cause increasing in local velocity that consequently causes the scour. In the present study, the maximum scour depth around L-shape groyne was computed based on laboratory experiments where different number of groynes and distances between them were used as sort of countermeasures to reduce the scour around the groynes foundations. The results showed clear decreasing in scour depth at increasing number of groynes and also distance between them in the limitation of this study.  A new formula based on experimental data was derived to calculate the local scour depth. This formula gave R2 =0.903 which reflecting good agreement to the results.  

Numerical Investigation of Local Scour Around Submerged Pipeline in Shoaling Conditions

2018 ◽  
Author(s):  
Ming-ming Liu ◽  
Ming Zhao ◽  
Lin Lu
Keyword(s):  
Water Waves ◽  
Slope Angle ◽  
Suspended Load ◽  
Local Scour ◽  
Navier Stokes ◽  
Bed Load ◽  
Scour Depth ◽  
Two Dimensional ◽  
Sediment Mass ◽  
Subsea Pipelines

Water waves play an important role in local scour around subsea pipelines laid on the sandy seabed, especially in shallow water regions. In this paper, a two-dimensional numerical model is employed to predict local scour around submarine pipelines under water waves in shoaling condition. The motion of water under waves is simulated by solving the Reynolds Averaged Navier-Stokes (RANS) equations. The evolution of the seabed surface near the pipeline is predicted by solving the conservation of the sediment mass, which transport in the water in the forms of bed load and suspended load. The main aim of this study is to investigate the effect of the seabed slope on the scour profiles and scour depth. To achieve this aim, numerical simulations of scour around a pipeline on a flat seabed and on a slope seabed with a slope angle of 15° are conducted for various wave conditions.

Estimation of maximum local scour depth around submerged spur-dike

2016 ◽  
pp. 193-199
Author(s):  
S.Y. Hao ◽  
Y.F. Xia ◽  
H. Xu
Keyword(s):  
Local Scour ◽  
Scour Depth ◽  
Spur Dike

scholarly journals ANALYSIS OF TSUNAMI SCOUR AROUND SQUARE STRUCTURES USING A PUMP-DRIVEN FLOW METHOD

2020 ◽  
pp. 8
Author(s):  
Rafael Aranguiz ◽  
Oscar Link ◽  
Jose Aliaga ◽  
Oscar Briones ◽  
Ruben Alarcon ◽  
...  
Keyword(s):  
Solitary Waves ◽  
Laboratory Experiments ◽  
Maximum Flow ◽  
Sediment Deposition ◽  
Scour Depth ◽  
Flow Depth ◽  
Field Surveys ◽  
Flow Method ◽  
Tsunami Scour ◽  
Tsunami Event

Estimation of the maximum scour depth is important for defining the size and depth of building foundations in order to avoid failure during a tsunami event (Jayaratne, et al 2016). Traditionally, tsunami scour has been studied in laboratory experiments that use solitary waves. However, it has been demonstrated that this type of wave does not represent well a real tsunami (Madsen et al, 2008). In addition, results from field surveys are based on the scour depth after the tsunami event, studying only the maximum flow depth, and ignoring other hydrodynamic features such as velocity and wave period, as well as sediment deposition. The main objective of this research is to estimate maximum tsunami scour around rectangular structures as a function of realistic tsunami variables.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/ykb-JyL7lsE

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