scholarly journals Investigation of local scour around tandem piers for different skew-angles

2018 ◽  
Vol 40 ◽  
pp. 03008 ◽  
Author(s):  
Sargol Memar ◽  
Mohammad Zounemat-Kermani ◽  
Ali-Asghar Beheshti ◽  
Giovanni De Cesare ◽  
Anton J. Schleiss
Keyword(s):  
Flow Direction ◽  
Local Scour ◽  
Scour Depth ◽  
Skew Angle ◽  
Approach Velocity ◽  
Sheltering Effect ◽  
Skew Angles

In the present study the effect of the skew-angle of the alignment of tandem piers on local scour depth around them is investigated. The tandem piers were aligned with different skew-angles of θ=0°,30°,45°,60°,90° with respect to the flow direction. The results indicatethat with the increment of the skew-angle, the influence of sheltering effects is decreased. In other word, since the sheltering effect of the upstream pier is declined (which reduces the approach velocity for the downstream pier) the scour depth around downstream pier increases. The results show that the maximum scour depth occurs at both piers for the skew-angle of θ=45°.Furthermore, the best configuration to aligned tandem piers was achieved at the skew-angle of θ=30°.

scholarly journals Nose-Angle Bridge Piers as Alternative Countermeasures for Local Scour Reduction

2018 ◽  
Vol 13 (2) ◽  
pp. 110-120 ◽  
Author(s):  
Ibtesam Abudallah Habib ◽  
Wan Hanna Melini Wan Mohtar ◽  
Atef Elsaiad ◽  
Ahmed El-Shafie
Keyword(s):  
Froude Number ◽  
Local Scour ◽  
Bridge Piers ◽  
Scour Depth ◽  
Skew Angle ◽  
Flow Angle ◽  
Sediment Size ◽  
Low Froude Number ◽  
Skew Angles ◽  
Depth Reduction

This study investigates the performance nose-angle piers as countermeasures for local scour reduction around piers. Four nose angles were studied, i.e., 90°, 70°, 60° and 45° and tested in a laboratory. The sediment size was fixed at 0.39 mm whereas the flow angle of attack (or skew angle) was varied at four angles, i.e., skew angles, i.e., 0°, 10°, 20° and 30°. Scour reduction was clear when decreasing nose angles and reached maximum when the nose angle is 45°. Increasing the flow velocity and skew angle was subsequently increasing the scour profile, both in vertical and transversal directions. However, the efficiency of nose angle piers was only high at low Froude number less than 0.40 where higher Froude number gives minimal changes in the maximum scour depth reduction. At a higher skew angle, although showed promising maximum scour depth reduction, the increasing pier projected width resulted in the increase of transversal lengths.

An experimental study into local scour in a channel caused by a 90° bend

2006 ◽  
Vol 33 (7) ◽  
pp. 902-911 ◽  
Author(s):  
Jueyi Sui ◽  
Daxian Fang ◽  
Bryan W Karney
Keyword(s):  
Froude Number ◽  
Flow Direction ◽  
Local Scour ◽  
Scour Depth ◽  
Factors Affecting ◽  
Downstream Section ◽  
Series Of Experiments ◽  
Bed Material ◽  
Hydraulic Variables

Based on a series of experiments, this paper explores the influence of a 90° change in flow direction on local scouring. The influence on local scour patterns due to hydraulic parameters such as the Froude number, the slope of the protection wall, the width of the protection apron along the outside wall of the downstream section, and the grain size of the channel bed material is examined. Protection-wall slopes ranging from 1:0.5 to 1:4 (vertical to horizontal) were investigated, as were different widths of the protection apron; the goal was to ascertain the role of these variables in local scour patterns in the vicinity of the bend. The factors affecting local scour depth are related through empirical equations to key hydraulic variables, the slope of the protection wall, and the width of the protection apron.Key words: bent flume, channel erosion, Froude number, scour depth, slope of protection wall (SPW), width of protection apron (WPA).

scholarly journals Modeling Local Scour around a Cylindrical Pier with Circular Collar with Tilt Angles (Counterclockwise around the Direction of the Channel Cross-Section) in Clear-Water

Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3281
Author(s):  
Hongliang Qi ◽  
Weiping Tian ◽  
Haochi Zhang
Keyword(s):  
Cross Section ◽  
Tilt Angle ◽  
Early Stage ◽  
Flow Direction ◽  
Local Scour ◽  
Channel Cross Section ◽  
Scour Depth ◽  
Clear Water ◽  
Eddy Simulation ◽  
Scouring Depth

This research explores how a circular collar with a tilt angle (counterclockwise around the direction of the channel cross-section) could affect the local scour depth around a single cylindrical pier in clear-water based on Large Eddy Simulation (LES) in six cases. The results show that a horizontal circular collar is the best for reducing the local scour depth. With the increases of the tilt angle, the effect on reducing the local scour depth decreases gradually and is even counterproductive at the scour equilibrium. At the early stage of scouring, cases with circular collars show obvious scouring depth reductions. The smaller the tilt angle is, the better and longer-lasting the protection that the circular collar can provide. When the tilt angle is smaller than 5°, the location of the maximum local scouring is around 90–115° (the angle is measured clockwise from the flow direction) on both sides of the pier. When the tilt angle is greater than 5°, the depth of local scouring in the range around −115° to 115° is close to the maximum local scouring depth. Significantly larger areas reach the maximum scouring depth when the tilt angle increases. Compared to Case 1 (the pier without a circular collar), in the cases with a circular collar, the topographies downwards the pier in 1.0D (D is the diameter of the bridge pier) are changed to siltation from scouring. The topography downwards the pier changes from scouring to siltation with the increase of the tilt angle, and the shape of siltation changes from a long-narrow rectangle to an equilateral triangle. This study may provide valuable insights into the protection of the local scour of the pier.

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 Influence of Skew Angles on Box Type Bridge

2020 ◽  
Vol 9 (7) ◽  
pp. 64-69
Keyword(s):  
Finite Element ◽  
Earth Pressure ◽  
Live Load ◽  
Skew Angle ◽  
Dead Load ◽  
Shear Forces ◽  
Modeling And Analysis ◽  
Finite Element Software ◽  
Skew Angles ◽  
Bottom Slab

In the present study, modeling and analysis of a three-lane three-span box bridge has been carried out by using finite element software STAAD pro.v8i. The study has been execute to find the effect of skew angle on all bride slabs (top slab, bottom slab, outer walls, inner walls) under various loads (dead load, live load, surfacing load, earth pressure, temperature and live load surcharge) and their combinations using IRC 6:2016. Skew angles taken for study ranges from 00 to 700 with an interval of 100 . Parameters that are mainly examined are longitudinal moments, transverse moments, torsional moments, shear forces and displacements. It has been observed that with the increase of skew angle all the parameters increases with the increase of skew angles in all slabs.

Clear-water local scour at wide piers in shallow-water flow

2014 ◽  
Vol 9 (3) ◽  
pp. 331-343 ◽  
Author(s):  
N. Ahmad ◽  
T. Mohamed ◽  
F. H. Ali ◽  
B. Yusuf
Keyword(s):  
Laboratory Data ◽  
Local Scour ◽  
The Other ◽  
Scour Depth ◽  
Temporal Development ◽  
Clear Water ◽  
Shallow Water Flow ◽  
Equilibrium Time ◽  
Sediment Size ◽  
Flow Intensity

Laboratory data for local scour depth regarding the size of wide piers are presented. Clear water scour tests were performed for various pier widths (0.06, 0.076, 0.102, 0.14 and 0.165 m), two types of pier shapes (circular and rectangular) and two types of uniform cohesionless bed sediment (d50 = 0.23 and d50 = 0.80 mm). New data are presented and used to demonstrate the effects of pier width, pier shape and sediment size on scour depth. The influence of equilibrium time (te) on scouring processes is also discussed. Equilibrium scour depths were found to decrease with increasing values of b/d50. The temporal development of equilibrium local scour depth with new laboratory data is demonstrated for flow intensity V/Vc = 0.95. On the other hand, the results of scour mechanism have shown a significant relationship between normalized volume of scoured and deposited with pier width, b. The experimental data obtained in this study and data available from the literature for wide piers are used to evaluate predictions of existing methods.

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