Local scour depth at a bridge pier protected by a collar in steady and unsteady flow

2019 ◽  
Vol 172 (6) ◽  
pp. 301-311 ◽  
Author(s):  
Mojtaba Karimaei Tabarestani ◽  
Amir Reza Zarrati
Keyword(s):  
Unsteady Flow ◽  
Local Scour ◽  
Bridge Pier ◽  
Scour Depth

scholarly journals Local Scour of Bridge Pier Sited on a Multi-Layered Sedimentary Bed in Rivers

2020 ◽  
Vol 144 ◽  
pp. 01008
Author(s):  
Shaolin Yue ◽  
Huan Zhou ◽  
Wenlong Zhu ◽  
Minxi Zhang
Keyword(s):  
Local Scour ◽  
Bridge Pier ◽  
Maximum Depth ◽  
Bridge Piers ◽  
Scour Depth ◽  
Bridge Safety ◽  
Particle Sorting ◽  
River Bed ◽  
Weihe River ◽  
Sediment Particles

The riverbeds or sea beds are usually composed of multi-layers of sediments. The scour around bridge piers sited on such beds is vital to the bridge safety, but is still very difficult to be predicated as its complicated interaction between the flow and bed layers. A simple model is proposed in this study for calculating the local scour maximum depth around bridge piers sited on multi-layer of sedimentary bed, which is based on HEC-18 formula revised by Richardson and Davis (2001) and the formula of the repose angle of sediment particles proposed by Cheng (1993). This model considers the particle sorting when the scour proceeds. An application of the model into the local scour depth of Guopan bridge pier sited on the Weihe River bed in Baoji city of China preliminarily demonstrates its reliability to calculate the local scour maximum depth around bridge piers sited on multi-layer of sedimentary bed.

Maximum Local Scour Depth at Bridge Piers under Unsteady Flow

2009 ◽  
Vol 135 (7) ◽  
pp. 609-614 ◽  
Author(s):  
Jihn-Sung Lai ◽  
Wen-Yi Chang ◽  
Chin-Lien Yen
Keyword(s):  
Unsteady Flow ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth

scholarly journals Effects of Dynamical Change in Water Level on Local Scouring around Bridge Piers Based on In-Situ Experiments

Water ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3015
Author(s):  
Takuma Kadono ◽  
Sho Kato ◽  
Shinichiro Okazaki ◽  
Toshinori Matsui ◽  
Yoshio Kajitani ◽  
...  
Keyword(s):  
Water Level ◽  
Local Scour ◽  
Bridge Pier ◽  
Angle Of Repose ◽  
Bridge Piers ◽  
Scour Depth ◽  
Water Level Change ◽  
Protection Zone ◽  
Level Change ◽  
In Situ Experiments

To evaluate the stability of bridge piers affected by the local scouring, the existing formulas for estimating the maximum local scour depth have been developed based on the results of experiments conducted under a constant water level. However, the applicability of these formulas to the cases where the water level rises and falls, such as a water level change in a real river, is not clear. In this study, water flow experiments were conducted on cylindrical and oval bridge pier models to investigate the effect of iterated water level change on the progression of local scour around piers. Results of experiments with cylindrical and oval pier showed that the local scour depth and length increased by an iterated action of the water level change; however, these values converged after the number of iterated actions reached a certain time. The local scour length at upstream of the bridge pier was approximately 1.8 times larger than the theoretical value, which was calculated through the local scour depth and angle of repose in water. The local scour length is an important parameter for defining the streambed protection zone, which is one of the measures against local scour, and we showed that the streambed protection zone needs to be defined more widely.

scholarly journals Local scour around a bridge pier under ice-jammed flow condition – an experimental study

2021 ◽  
Vol 69 (3) ◽  
pp. 275-287
Author(s):  
Jun Wang ◽  
Zhixing Hou ◽  
Hongjian Sun ◽  
Bihe Fang ◽  
Jueyi Sui ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Local Scour ◽  
Bridge Pier ◽  
Scour Depth ◽  
Flow Conditions ◽  
Hole Depth ◽  
Open Flow ◽  
Ice Jam ◽  
Scour Hole ◽  
Ice Jam Thickness

Abstract The appearance of an ice jam in a river crucially distorts local hydrodynamic conditions including water level, flow velocity, riverbed form and local scour processes. Laboratory experiments are used for the first time here to study ice-induced scour processes near a bridge pier. Results show that with an ice sheet cover the scour hole depth around a bridge is increased by about 10% compared to under equivalent open flow conditions. More dramatically, ice-jammed flows induce both greater scour depths and scour variability, with the maximum scour depth under an ice-jammed flow as much as 200% greater than under equivalent open flow conditions. Under an ice-jammed condition, both the maximum depth and length of scour holes around a bridge pier increase with the flow velocity while the maximum scour hole depth increases with ice-jam thickness. Also, quite naturally, the height of the resulting deposition dune downstream of a scour hole responds to flow velocity and ice jam thickness. Using the laboratory data under ice-jammed conditions, predictive relationships are derived between the flow’s Froude number and both the dimensionless maximum scour depth and the dimensionless maximum scour length.

scholarly journals Application of Improved GMDH Models to Predict Local Scour Depth at Complex Bridge Piers

2020 ◽  
Vol 6 (1) ◽  
pp. 69-84 ◽  
Author(s):  
Habibeh Ghodsi ◽  
Mohammad Javad Khanjani
Keyword(s):  
Local Scour ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Group Method ◽  
Scour Depth ◽  
Empirical Equations ◽  
Depth Prediction ◽  
Pile Cap ◽  
Data Points ◽  
Statistical Criteria

Scour depth prediction is a vital issue in bridge pier design. Recently, good progress has been made in the development of artificial intelligence (AI) to predict scour depth around hydraulic structures base such as bridge piers. In this study, two hybrid intelligence models based on combination of group method of data handling (GMDH) with harmony search algorithm (HS) and shuffled complex evolution (SCE) have been developed to predict local scour depth around complex bridge piers using 82 laboratory data measured by authors and  615 data points from published literature. The results were compared to conventional GMDH models with two kinds of transfer functions called GMDH1 and GMDH2. Based upon the pile cap location, data points were divided into three categories. The performance of all utilized models was evaluated by the statistical criteria of R, RMSE, MAPE, BIAS, and SI. Performances of developed models were evaluated by experimental data points collected in laboratory experiments, together with commonly empirical equations. The results showed that GMDH2SCE was the superior model in terms of all statistical criteria in training when the pile cap was above the initial bed level and completely buried pile cap. For a partially-buried pile cap, GMDH1SCE offered the best performance. Among empirical equations, HEC-18 produced relatively good performances for different types of complex piers. This study recommends hybrid GMDH models, as powerful tools in complex bridge pier scour depth prediction.

Reduction of local scour around a bridge pier by using different shapes of pier slots and collars

2020 ◽  
Vol 20 (3) ◽  
pp. 1006-1015 ◽  
Author(s):  
A. Bestawy ◽  
T. Eltahawy ◽  
A. Alsaluli ◽  
A. Almaliki ◽  
M. Alqurashi
Keyword(s):  
Three Dimensional ◽  
Laser Scanner ◽  
Local Scour ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Scour Depth ◽  
Contour Maps ◽  
Reduction Methods ◽  
Analysis System ◽  
Bridge Failure

Abstract Local scour around bridge piers is one of the main causes of bridge failure all over the world. Experimental and hydraulic models were carried out to investigate two types of scour reduction methods around a single cylindrical pier, namely the pier's slots and collars. The efficiency of various types of pier slots and circular collars around the pier's base in reducing scour were studied. A new shape of a conical collar was developed by the authors and examined along with other shapes. The results revealed that collars, in general, have more influence in reducing scour depth than slots made in the front and rear of bridge piers. The sigma-slot acts better than other tested slots, with a reduction in the scour depths of 59.3% and 52.8% at the upstream and downstream of the pier, respectively. On the other hand, the conical collar appeared to be the most effective collar shape in reducing the scour around the bridge pier, with a 61.1% reduction in the scour depth downstream of the pier. A three-dimensional laser scanner was used to capture the bed topography at the end of each experiment and contour maps of the deformed bed were produced. A one-dimensional Hydrologic Engineering Center-River Analysis System model was developed with a single bridge pier to predict the scour depth around the pier in an attempt to introduce new values for the pier nose shape factor, , which describes the tested piers.

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.

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