Prediction of Maximum Scour Depth near Spur Dikes in Uniform Bed Sediment Using Stacked Generalization Ensemble Tree-Based Frameworks

Abstract The effect of using permeable spur dikes on the produced maximum scour depth compared to that of solid spur dikes is numerically investigated. The numerical model used for such purpose is the Nays-2DH model of the International River Interface Cooperative (iRIC) software package for bed and bank erosion. The model results are verified using the experimental data collected in this study by conducting experiments on five different models of spur dikes having different opening ratios. Using the statistical performance indices, the root mean square error and the coefficient of determination, the results showed an acceptable agreement between the numerical model results for the relative maximum scour depth defined by the ratio of the maximum scour depth to the flow depth and their corresponding observed values. A new empirical equation using nonlinear regression is developed using the experimental data collected in this study and tested with another existing empirical equation available in the literature for their accuracy in determining the relative maximum scour depth.

Download Full-text

Estimation of maximum scour depth near a spur dike

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2015-0280 ◽

2016 ◽

Vol 43 (3) ◽

pp. 270-278 ◽

Cited By ~ 16

Author(s):

Manish Pandey ◽

Z. Ahmad ◽

P.K. Sharma

Keyword(s):

Natural Phenomenon ◽

Scour Depth ◽

Flowing Water ◽

Performance Indices ◽

Spur Dike ◽

Bed Erosion ◽

River Bed ◽

Spur Dikes ◽

Dike Failure ◽

Better Than

Scour is a natural phenomenon in rivers caused by the erosive action of the flowing water on the bed and banks. Spur dikes are constructed across the flow to protect the bank from erosion by shifting of the river away from the bank. The spur dike undermines due to river-bed erosion and scouring, which is generally recognized as the main cause of spur dike failure. In this study, accuracy of existing equations for the computation of maximum scour depth has been checked with available data in the literature and data collected in the present study using graphical and statistical performance indices. Three new relationships are also proposed to estimate the maximum scour depth and maximum scour length upstream and downstream of spur dike. This new relationship for maximum scour depth is shown to perform better than other existing equations.

Download Full-text

Enhancing Maximum Scour Depth Determination for Spur Dikes Using a Validated Two-Dimensional Model

World Environmental and Water Resources Congress 2020 ◽

10.1061/9780784482971.009 ◽

2020 ◽

Author(s):

Yeo Howe Lim ◽

Mathew Lee Cox

Keyword(s):

Scour Depth ◽

Two Dimensional ◽

Dimensional Model ◽

Depth Determination ◽

Two Dimensional Model ◽

Spur Dikes

Download Full-text

Numerical Simulation of the Influence of Spur Dikes Spacing on Local Scour and Flow

Applied Sciences ◽

10.3390/app9112306 ◽

2019 ◽

Vol 9 (11) ◽

pp. 2306

Author(s):

Jian Ning ◽

Guodong Li ◽

Shanshan Li

Keyword(s):

Shear Stress ◽

Pearson Correlation ◽

Fixed Bed ◽

Maximum Velocity ◽

Turbulent Energy ◽

Local Scour ◽

Shielding Effect ◽

Scour Depth ◽

Spur Dike ◽

Spur Dikes

The spacing of spur dikes is an important consideration for the layout of spur dike channels. This study focuses on the local scour morphology and flow field characteristics of spur dikes with different spacings. The results show that the maximum scour depth is generally found in the vicinity of the first spur dike head. With the increase of the spacing of spur dikes, the shielding effect of the first spur dike is weakened. The maximum velocity in the main flow zone is twice that of the approach flow velocity in the fixed bed. But it is approximately the same as the incoming velocity in equilibrium scouring. The maximum turbulent energy appears to be mainly located in the backflow area of the fourth spur dike in the fixed bed, while the maximum value appears at the second spur dike head in the movable bed. Further, the shear stress decreases as scouring develops. Pearson correlation analysis was carried out between scour depth and shear stress. The analysis results are significantly correlated, indicating that the bed shear stress plays a prominent role in the scouring process. These discoveries can serve as a guide to determine the most reasonable spacing of spur dikes.

Download Full-text

Improving the 2D Numerical Simulations on Local Scour Hole around Spur Dikes

Water ◽

10.3390/w13111462 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1462

Author(s):

Chung-Ta Liao ◽

Keh-Chia Yeh ◽

Yin-Chi Lan ◽

Ren-Kai Jhong ◽

Yafei Jia

Keyword(s):

Numerical Simulation ◽

Three Dimensional ◽

Local Scour ◽

Bridge Piers ◽

Scour Depth ◽

Foundation Design ◽

Mobile Bed ◽

Scour Hole ◽

Scour Holes ◽

Spur Dikes

Local scour is a common threat to structures such as bridge piers, abutments, and dikes that are constructed on natural rivers. To reduce the risk of foundation failure, the understanding of local scour phenomenon around hydraulic structures is important. The well-predicted scour depth can be used as a reference for structural foundation design and river management. Numerical simulation is relatively efficient at studying these issues. Currently, two-dimensional (2D) mobile-bed models are widely used for river engineering. However, a common 2D model is inadequate for solving the three-dimensional (3D) flow field and local scour phenomenon because of the depth-averaged hypothesis. This causes the predicted scour depth to often be underestimated. In this study, a repose angle formula and bed geometry adjustment mechanism are integrated into a 2D mobile-bed model to improve the numerical simulation of local scour holes around structures. Comparison of the calculated and measured bed variation data reveals that a numerical model involving the improvement technique can predict the geometry of a local scour hole around spur dikes with reasonable accuracy and reliability.

Download Full-text

Prediction of time variation of scour depth around spur dikes using neural networks

Journal of Hydroinformatics ◽

10.2166/hydro.2011.106 ◽

2011 ◽

Vol 14 (1) ◽

pp. 180-191 ◽

Cited By ~ 15

Author(s):

Hojat Karami ◽

Abdollah Ardeshir ◽

Mojtaba Saneie ◽

S. Amin Salamatian

Keyword(s):

Neural Networks ◽

Regression Model ◽

Time Variation ◽

Back Propagation ◽

Maximum Depth ◽

Scour Depth ◽

Effective Parameters ◽

Spur Dike ◽

Feed Forward Back Propagation ◽

Spur Dikes

The maximum depth of scouring around spur dikes plays an important role in the hydraulic design process. There have been many studies on the maximum depth of scouring, but there is little information available on the time variation of scour depth. In this paper, the time variation of scouring around the first spur dike in a series was investigated experimentally. Experiments were carried out in four different bed materials under different flow intensities (U/Ucr). To achieve a time development of scouring around the first spur dike, more than 750 sets of experimental data were collected. The results showed that 70–90% of the equilibrium scour depths were occurring during the initial 20% of the overall time of scouring. Based on the data analysis, a regression model and artificial neural networks (ANNs) were developed. The models were compared with other empirical equations in the literature. However, the results showed that the developed regression model is quite accurate and more practical, but the ANN models by feed forward back propagation and radial basis function provide a better prediction of observation. Finally, by sensitivity analysis, the most and the least effective parameters, which affected time variation of scouring, were determined.

Download Full-text

Experimental Investigation of Scour Prediction Methods for Offshore Tripod and Hexapod Foundations

Journal of Marine Science and Engineering ◽

10.3390/jmse8110856 ◽

2020 ◽

Vol 8 (11) ◽

pp. 856

Author(s):

Xuan Ni ◽

Leiping Xue

Keyword(s):

Laboratory Experiments ◽

Prediction Methods ◽

Scour Depth ◽

Effective Diameter ◽

Bed Sediment ◽

Clear Water ◽

Pile Groups ◽

Steady Current ◽

Complex Shapes ◽

Equilibrium Scour Depth

Scour prediction is essential for the design of offshore foundations. Several methods have been proposed to predict the equilibrium scour depth for monopiles. By introducing an effective diameter, such methods could also be applied to predicting scour depth for pile groups. Yet, there are still difficulties in estimating the equilibrium scour depth of foundations in complex shapes, such as the tripod foundation. This study investigates the clear-water scour around the tripod and hexapod foundations through laboratory experiments, with uniform bed sediment and steady current. Here, the authors propose an approach to calculate the effective diameter for the tripod and hexapod models, which is similarly as for the pile groups. Three widely-used methods in predicting equilibrium scour depth have been evaluated, and the best method is recommended.

Download Full-text

Numerical scour modeling around parallel spur dikes in FLOW-3D

10.5194/dwes-2017-21 ◽

2017 ◽

Cited By ~ 3

Author(s):

Hanif Pourshahbaz ◽

Saeed Abbasi ◽

poorya taghvaei

Keyword(s):

Numerical Model ◽

3D Model ◽

Flow Characteristics ◽

3D Models ◽

Scour Depth ◽

Spur Dike ◽

Accuracy Level ◽

Bank Protection ◽

Numerical Research ◽

Spur Dikes

Abstract. Spur dikes are some structures which are built in the flow path with the aim of changing flow characteristics in order to bed and bank protection in rivers. These sudden changes in properties caused by the existence of spur dikes, produces erosion and sedimentation around them. In this paper, effects of series of parallel spur dikes have been investigated numerically. For this purpose, by using experimental and numerical research results from technical literatures, the numerical model conducted in FLOW-3D commercial software and the data were compared with experimental and SSIIM results. The results showed that Froude number and the ratio of U/Ucr affect the accuracy of the models. As a result, by discharge increasing, FLOW-3D models need to be calibrated again. Also, by using a calibrated FLOW-3D model, calculation accuracy of the scour depth at the bottom of the spur dikes becomes better and the accuracy level in the modeling of the surface morphology improves 7 percent more than SSIIM software in the bottom of the first spur dike, more than 80 percent at the bottom of the second spur dike and approximately 40 percent at the bottom of the last spur dike.

Download Full-text