Clear-Water Scour around Bridge Abutments under Backwater Conditions

1996 ◽  
Vol 1523 (1) ◽  
pp. 196-202 ◽  
Author(s):  
Terry W. Sturm ◽  
Aftab Sadiq
Keyword(s):  
Flow Distribution ◽  
Scour Depth ◽  
Clear Water ◽  
Bridge Abutments ◽  
Bridge Abutment ◽  
Rectangular Channels ◽  
Contraction Ratio ◽  
Bridge Approach ◽  
Contraction Scour ◽  
Abutment Scour

An experimental study was conducted of the depth of clear-water scour around the end of a square-edged bridge abutment terminating in the floodplain of a compound channel. The study's purpose was to improve current techniques of abutment scour prediction, which are based primarily on laboratory studies in rectangular channels. It is indicated that a discharge contraction ratio arising from a theoretical contraction scour analysis for equilibrium conditions can be used for explaining the effect of flow distribution on the local abutment scour depth in the case where significant backwater occurs from bridge contraction. The use of reference values of approach flow depth and velocity in the floodplain for undisturbed conditions without the bridge is shown to collapse experimental results for scour depth in both the case of a contraction with negligible backwater, and the case of a contraction with significant backwater in the bridge approach section.

Temporal scour development at bridge abutments with a collar

2007 ◽  
Vol 34 (4) ◽  
pp. 549-556 ◽  
Author(s):  
Şerife Yurdagül Kumcu ◽  
Mustafa Gögüş ◽  
Mehmet Ali Kökpinar
Keyword(s):  
Temporal Variation ◽  
Vertical Wall ◽  
Scour Depth ◽  
Clear Water ◽  
Flow Conditions ◽  
Bridge Abutments ◽  
Time Period ◽  
Bridge Abutment ◽  
Laboratory Flume ◽  
Sediment Particles

This study investigated the reduction of scour around a vertical-wall bridge abutment using rectangular collars for clear-water flow conditions over uniform sediment particles in a laboratory flume. Collars of different sizes and at different elevations were tested to determine the temporal variation of scour depth around the bridge abutment. The development of scour around the abutments with and without a collar for a time period of 6 h was studied, and observed scour depths were compared. Experimental results showed that, in addition to protecting the abutments against erosion, the addition of a collar is effective in reducing the rate of temporal scour development. A comparison of the present results with those from previous studies revealed that the effectiveness of a collar increases with a decrease in the elevation of the collar and an increase in the width of the collar.Key words: bridge abutment, collar, experimentation, hydraulics, scour, temporal variation.

Further studies of incipient motion and shear stress on local scour around bridge abutment under ice cover

2014 ◽  
Vol 41 (10) ◽  
pp. 892-899 ◽  
Author(s):  
Peng Wu ◽  
Faye Hirshfield ◽  
Jueyi Sui
Keyword(s):  
Experimental Study ◽  
Reynolds Number ◽  
Shear Stress ◽  
Open Channel ◽  
Ice Cover ◽  
Scour Depth ◽  
Incipient Motion ◽  
Clear Water ◽  
Bridge Abutments ◽  
Bridge Abutment

An experimental study was conducted to investigate the scour development around bridge abutments under ice cover with non-uniform natural sands. Two abutments and three non-uniform sediments were used in the research. The mechanism of incipient motion for non-uniform sediments under ice cover was analyzed. By introducing scour angles around two abutments, a relationship between maximum scour depth and velocity was established for clear-water scour under ice cover. Dimensionless shear stress was also calculated and compared with shear Reynolds number for non-uniform sediments. The maximum scour depth and dimensionless shear stress were investigated under both open channel, smooth cover and rough covered conditions. Results show that around the square abutment, the scour angle is smaller than that of the semi-circular abutment. For clear water scour, the maximum scour depth increases due to the presence of ice cover.

Experimental study of clear-water contraction scour

2020 ◽  
Vol 20 (3) ◽  
pp. 943-952 ◽  
Author(s):  
Ravindra Kumar Singh ◽  
Manish Pandey ◽  
Jaan H. Pu ◽  
Srinivas Pasupuleti ◽  
Vasanta G. Kumar Villuri
Keyword(s):  
Experimental Study ◽  
Reasonable Agreement ◽  
Time Dependent ◽  
Scour Depth ◽  
Clear Water ◽  
Equilibrium Conditions ◽  
Bridge Abutment ◽  
Water Conditions ◽  
Contraction Scour ◽  
Equilibrium Scour Depth

Abstract In this paper, experimental results of clear-water scour on a sand bed under short contractions were studied. Sequences of test runs were performed under clear-water conditions for three different contraction ratios. The outcomes of the experiments were employed to define the effects of various parameters on equilibrium scour depth under clear-water scour conditions. In this work, the precision of three maximum scour depth equations was tested from previous studies for contraction scour cases. Two new analytical equations were proposed to calculate time-dependent scour depth and maximum scour at equilibrium conditions, respectively, from the study. The proposed equations were validated using measurements from the present study as well as from previous literature, and the equations show a reasonable agreement between measured and computed values of scour depth under clear-water conditions in short contraction. The presented equations can be used for studying protection of the submerged portion at a bridge abutment or any similar structure.

Abutment scour in clear-water and live-bed conditions by GMDH network

2013 ◽  
Vol 67 (5) ◽  
pp. 1121-1128 ◽  
Author(s):  
Mohammad Najafzadeh ◽  
Gholam-Abbas Barani ◽  
Masoud Reza Hessami Kermani
Keyword(s):  
Back Propagation ◽  
Support Vector ◽  
Group Method ◽  
Scour Depth ◽  
Back Propagation Algorithm ◽  
Clear Water ◽  
Sediment Size ◽  
Svm Model ◽  
Vector Machines ◽  
Abutment Scour

In the present study, the Group Method of Data Handling (GMDH) network has been utilized to predict abutments scour depth for both clear-water and live-bed conditions. The GMDH network was developed using a Back Propagation algorithm (BP). Input parameters that were considered as effective variables on abutment scour depth included properties of sediment size, geometry of bridge abutments, and properties of approaching flow. Training and testing performances of the GMDH network were carried out using dimensionless parameters that were collected from the literature. The testing results were compared with those obtained using the Support Vector Machines (SVM) model and the traditional equations. The GMDH network predicted the abutment scour depth with lower error (RMSE (root mean square error) = 0.29 and MAPE (mean absolute percentage of error) = 0.99) and higher (R = 0.98) accuracy than those performed using the SVM model and the traditional equations.

scholarly journals Length Parameter for Scaling Abutment Scour Depth

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3508
Author(s):  
Puer Xu ◽  
Niansheng Cheng ◽  
Maoxing Wei
Keyword(s):  
Large Scale ◽  
Scour Depth ◽  
Length Scale ◽  
Bed Shear Stress ◽  
Combined Effects ◽  
Flow Depth ◽  
Vortex System ◽  
Bridge Abutment ◽  
Abutment Scour ◽  
Scale Turbulence

Flow constriction caused by bridge abutment increases bed shear stress and thus enhances local scour. For scaling the maximum scour depth at the abutment, either abutment length or flow depth has been empirically used in previous studies. By performing a step-by-step analysis, this study proposes a new length scale, which is able to represent combined effects of abutment length, approach flow depth and channel width. Physically, the new length scale describes the maximum possible dimension of the associated vortex system (or large-scale turbulence). Six series of data compiled from the published literature were used in the analysis. The results indicate that the new length scale helps improve the agreement of predictions with the experimental data.

scholarly journals ANFIS approach to the scour depth prediction at a bridge abutment

2010 ◽  
Vol 12 (4) ◽  
pp. 474-485 ◽  
Author(s):  
Mohammad Muzzammil
Keyword(s):  
Fuzzy Inference ◽  
Accurate Estimation ◽  
Scour Depth ◽  
Bridge Abutments ◽  
Anfis Model ◽  
Inference System ◽  
Model Studies ◽  
Depth Prediction ◽  
Bridge Abutment ◽  
Conventional Regression

An accurate estimation of the maximum possible scour depth at bridge abutments is of paramount importance in decision-making for the safe abutment foundation depth and also for the degree of scour counter-measure to be implemented against excessive scouring. Despite analysis of innumerable prototype and hydraulic model studies in the past, the scour depth prediction at the bridge abutments has remained inconclusive. This paper presents an alternative to the conventional regression model (RM) in the form of an adaptive network-based fuzzy inference system (ANFIS) modelling. The performance of ANFIS over RM and artificial neural networks (ANNs) is assessed here. It was found that the ANFIS model performed best among of these methods. The causative variables in raw form result in a more accurate prediction of the scour depth than that of their grouped form.

One-Dimensional and Two-Dimensional Estimates of Abutment Scour Prediction Variables

1998 ◽  
Vol 1647 (1) ◽  
pp. 18-26 ◽  
Author(s):  
Terry W. Sturm ◽  
Antonis Chrisochoides
Keyword(s):  
Vertical Wall ◽  
Two Dimensional ◽  
One Dimensional ◽  
Bridge Abutment ◽  
Overbank Flow ◽  
Bridge Approach ◽  
Surface Profiles ◽  
Abutment Scour ◽  
The One ◽  
D Model

An experimental study of the estimation of hydraulic parameters needed in bridge abutment scour formulas is presented. Two different compound channel geometries are studied with rough floodplains in shallow overbank flow. Vertical-wall and spill-through abutment shapes are included in the study, with the abutment face located on the floodplain for various embankment lengths. Water surface profiles and velocity distributions are measured and compared with predictions made by the one-dimensional (1-D) model WSPRO and a two-dimensional k-ε turbulence model developed in previous research. The results show that a 1-D model can predict scour parameters reasonably well in the bridge approach section but not in the bridge contraction section.

scholarly journals A Non-Tuned Machine Learning Technique for Abutment Scour Depth in Clear Water Condition

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 301 ◽  
Author(s):  
Hossein Bonakdari ◽  
Fatemeh Moradi ◽  
Isa Ebtehaj ◽  
Bahram Gharabaghi ◽  
Ahmed A. Sattar ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Fundamental Equation ◽  
Percentage Error ◽  
Scour Depth ◽  
Clear Water ◽  
Dimensionless Variable ◽  
Sediment Size ◽  
Wide Range ◽  
Abutment Scour ◽  
The Impact

Abutment scour is a complex three-dimensional phenomenon, which is one of the leading causes of marine structure damage. Structural integrity is potentially attainable through the precise estimation of local scour depth. Due to the high complexity of scouring hydrodynamics, existing regression-based relations cannot make accurate predictions. Therefore, this study presented a novel expansion of extreme learning machines (ELM) to predict abutment scour depth (ds) in clear water conditions. The model was built using the relative flow depth (h/L), excess abutment Froude number (Fe), abutment shape factor (Ks), and relative sediment size (d50/L). A wide range of experimental samples was collected from the literature, and data was utilized to develop the ELM model. The ELM model reliability was evaluated based on the estimation results and several statistical indices. According to the results, the sigmoid activation function (correlation coefficient, R = 0.97; root mean square error, RMSE = 0.162; mean absolute percentage error, MAPE = 7.69; and scatter index, SI = 0.088) performed the best compared with the hard limit, triangular bias, radial basis, and sine activation functions. Eleven input combinations were considered to investigate the impact of each dimensionless variable on the abutment scour depth. It was found that ds/L = f (Fe, h/L, d50/L, Ks) was the best ELM model, indicating that the dimensional analysis of the original data properly reflected the underlying physics of the problem. Also, the absence of one variable from this input combination resulted in a significant accuracy reduction. The results also demonstrated that the proposed ELM model significantly outperformed the regression-based equations derived from the literature. The ELM model presented a fundamental equation for abutment scours depth prediction. Based on the simulation results, it appeared the ELM model could be used effectively in practical engineering applications of predicting abutment scour depth. The estimated uncertainty of the developed ELM model was calculated and compared with the conventional and artificial intelligence-based models. The lowest uncertainty with a value of ±0.026 was found in the proposed model in comparison with ±0.50 as the best uncertainty of the other models.

scholarly journals Simultaneous Effect of Collar and Roughness on Reducing and Controlling the Local Scour around Bridge Abutment

2017 ◽  
Vol 65 (2) ◽  
pp. 491-499
Author(s):  
Hamed Shahsavari ◽  
Manouchehr Heidarpour ◽  
Mohammad Mohammadalizadeh
Keyword(s):  
Local Scour ◽  
Hydraulic Structures ◽  
Scour Depth ◽  
River Engineering ◽  
Crucial Importance ◽  
Clear Water ◽  
Simultaneous Effect ◽  
Bridge Abutment ◽  
Scouring Process ◽  
Local Roughness

Investigation of local scour around hydraulic structures particularly bridges is of crucial importance in river engineering. Bridge destruction mostly occurs as a result of scour phenomenon around piers and abutments, not because of structural weaknesses. Hence, finding a solution to reduce scour depth is momentous. In this study which was conducted in the conditions of clear water scour, the effect of local roughness and collar and also impact of using them simultaneously around bridge abutment were evaluated. The results demonstrated that the existence of roughness causes a reduction in the severity of scouring process and its final depth and the use of collar leads to a delay in the scouring process in addition to the ultimate reduction in the scour depth, which in case of using them simultaneously, scour depth decreases by about 83%.

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