Formula Type of Local Scour Depth on Spur Dike Nose

2014 ◽  
Vol 641-642 ◽  
pp. 271-274
Author(s):  
Qiang Ying
Keyword(s):  
Formation Process ◽  
Local Scour ◽  
Scour Depth ◽  
Calculation Methods ◽  
Spur Dike ◽  
Scour Hole ◽  
Main Factors ◽  
Formula Type ◽  
Suggested Formula

This passage introduces the formation process of scour hole, analyzes the main factors contributed to the local scour hole’s depth and classifies today’s calculation methods of scour depth into three categories. Then, given the conditions where those methods can be applied and drawbacks of those methods, this article also recommends some suggested formula in calculation.

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 Investigation of Local Scour around L-Shape Submerged Groynes in Clearwater Conditions

2021 ◽  
Vol 28 (3) ◽  
pp. 159-169
Author(s):  
Saleh Issa Khassaf ◽  
Budoor Mohammed Rashak
Keyword(s):  
Froude Number ◽  
Local Scour ◽  
Scour Depth ◽  
Contour Lines ◽  
Low Profile ◽  
Scour Hole ◽  
Number Flow ◽  
Flow Intensity ◽  
Good Determination ◽  
New Formula

Submerged Groynes are low profile linear structures that are generally located on the outside bank to form Groynes fields and prevent the erosion of stream banks by redirecting high-velocity flow away from the bank. This research was studied in detail through two major stages. The first stage of the study is based on laboratory experiments to measure the development of local scour around L-shape submerged Groyne with the time, and special attention is given to the effects of different hydraulic and geometric parameters on local scour. Also; maps were drawn showing contour lines that represented the bed levels for maximum scour depth after reaching the equilibrium case. The result showed that a decrease in the scour depth ratio due to the increasing submerged ratio, and the number of Groynes. While the scour hole geometry will increase with the Froude number, flow intensity, and the spacing between Groynes, the decreasing percentage in the scour hole was measured to be about (4.3) % and (4.4) % for decreasing the spacing between Groynes from (2Lg) to (1.5Lg). Besides, it was range about (11.1) % and (14.0) % when reducing the spacing from (1.5Lg) to (Lg) under the same value of maximum Froude number. The second stage of the study is based on experimental results. A new formula was developed by using statistical analysis and it was found that a good determination coefficient.

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

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.

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

Water ◽  
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.

scholarly journals Experimental Study of Local Scour around Caissons under Unidirectional and Tidal Currents

Water ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 640 ◽  
Author(s):  
Qiqi Xiang ◽  
Kai Wei ◽  
Fang Qiu ◽  
Changrong Yao ◽  
Yadong Li
Keyword(s):  
Cross Sections ◽  
Tidal Current ◽  
Opposite Effect ◽  
Tidal Currents ◽  
Local Scour ◽  
Bridge Engineering ◽  
Scour Depth ◽  
Factors Affecting ◽  
Main Factors ◽  
The Difference

Local scour around caissons under currents has become one of the main factors affecting the safety of foundation construction and operation in coastal and offshore bridge engineering. Local scour occurs not only in the operation stage, when the caisson has settled into the sediment, but also in the construction stage, when the caisson is suspended in water. In this study, the local scour induced by unidirectional and tidal currents around settled caissons with different cross-sections (circular, square, and diamond) was experimentally investigated. Circular and square caissons were selected to investigate the difference in local scour of suspended caissons under unidirectional and tidal currents. The main findings from the experimental results were: (1) the temporal development of scour under tidal current was slower than that of unidirectional current; (2) the effect of current type can significantly influence the size and location of maximum scour depth around circular and square caissons; (3) the appropriate choice of cross-section could reduce the maximum scour depth around the settled caisson; (4) the maximum scour depth of tidal current was smaller than that of unidirectional current when the caisson was settled into the sediment, while the opposite effect occurred when the caisson was suspended in water.

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 Experimental study of local scour around T-shaped spur dike in a meandering channel

2020 ◽  
Author(s):  
Ravi Prakash Tripathi ◽  
K. K. Pandey
Keyword(s):  
Froude Number ◽  
Research Work ◽  
Local Scour ◽  
Scour Depth ◽  
Spur Dike ◽  
Meandering Channel ◽  
Work Related ◽  
Channel Bend ◽  
River Training ◽  
Training Structure

Abstract A spur dike is mainly constructed as a river-training structure and is primarily used to prevent bank erosion. The restriction to flow caused by the construction of a spur dike promotes local scour around the structure. In the case of a dike placed in a channel bend, the scour becomes more aggressive. The literature review found that the research work related to local scour around a spur dike located in a meandering channel is very limited or minimal. Therefore, an experimental investigation was conducted to study the local scour process around a T-shaped spur dike placed at different locations along the outer bank (or concave) of a reverse-meandering channel. Non-dimensionalized empirical equations for temporal and maximum local scour depth were developed as the function of the Froude number of approach flow and spur dike location. It is observed that local scour around the dike increases with the increase in Froude number and location in the meander (measured from the entry to meander). The formulation for the maximum scour depth was further evaluated with the experimental data related to the 180° bend, from literature, and it was found that the proposed equation's application is very much limited.

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