scholarly journals Pier Scour Prediction in Non-Uniform Gravel Beds

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1696 ◽  
Author(s):  
Manish Pandey ◽  
Giuseppe Oliveto ◽  
Jaan H. Pu ◽  
P. K. Sharma ◽  
C. S. P. Ojha
Keyword(s):  
Scale Effects ◽  
Field Measurements ◽  
Laboratory Scale ◽  
Scour Depth ◽  
Pier Scour ◽  
Gravel Bed ◽  
Gravel Beds ◽  
Equilibrium Scour Depth ◽  
Gravel Bed Streams ◽  
Curve Fitting Method

Pier scour has been extensively studied in laboratory experiments. However, scour depth relationships based on data at the laboratory scale often yield unacceptable results when extended to field conditions. In this study, non-uniform gravel bed laboratory and field datasets with gravel of median size ranging from 2.7 to 14.25 mm were considered to predict the maximum equilibrium scour depth at cylindrical piers. Specifically, a total of 217 datasets were collected: 132 from literature sources and 85 in this study using new experiments at the laboratory scale, which constitute a novel contribution provided by this paper. From the analysis of data, it was observed that Melville and Coleman’s equation performs well in the case of laboratory datasets, while it tends to overestimate field measurements. Guo’s and Kim et al.’s relationships showed good agreements only for laboratory datasets with finer non-uniform sediments: deviations in predicting the maximum scour depth with non-uniform gravel beds were found to be significantly greater than those for non-uniform sand and fine gravel beds. Consequently, new K-factors for the Melville and Coleman’s equation were proposed in this study for non-uniform gravel-bed streams using a curve-fitting method. The results revealed good agreements between observations and predictions, where this might be an attractive advancement in overcoming scale effects. Moreover, a sensitivity analysis was performed to identify the most sensitive K-factors.

scholarly journals Evaluation of governing parameters on pier scour geometry

2017 ◽  
Vol 44 (1) ◽  
pp. 48-58 ◽  
Author(s):  
Priscilla Williams ◽  
Tirupati Bolisetti ◽  
Ram Balachandar
Keyword(s):  
Scale Effects ◽  
Estimation Method ◽  
Estimation Methods ◽  
Scour Depth ◽  
Pier Scour ◽  
Densimetric Froude Number ◽  
Scouring Process ◽  
Equilibrium Scour Depth ◽  
Definition Of ◽  
Limiting Value

Current scour estimation methods typically over-predict scour, resulting in uneconomical design. This tendency is partly due to the complexity of the scouring process, which indicates that some of its aspects are still not well understood, and can also be attributed to scale effects. Here, experiments are conducted to isolate the influence of relative coarseness (D/d50) and flow shallowness (h/D) on scour depth. For the range of D/d50 in the present study, equilibrium scour depth (dse/D) decreases with increasing D/d50 until a limiting value of D/d50 = 175, after which dse/D ≈ 0.75. Furthermore, dse/D is found to depend on h/D when all other scour influencing parameters are held constant. A revised definition of the densimetric Froude number using the velocity along the separating streamline is shown to have an influential role in scour. An improved scour estimation method employing these parameters is presented and compared with current methods.

Evaluation of Selected Pier-Scour Equations Using Field Data

1996 ◽  
Vol 1523 (1) ◽  
pp. 186-195 ◽  
Author(s):  
Mark N. Landers ◽  
David S. Mueller
Keyword(s):  
Field Measurements ◽  
Bridge Piers ◽  
Critical Ratio ◽  
Scour Depth ◽  
Flow Depth ◽  
Clear Water ◽  
Pier Scour ◽  
Logarithmic Space ◽  
State Highway ◽  
Federal Highway

Field measurements of channel scour at bridges are needed to improve the understanding of scour processes and the ability to accurately predict scour depths. An extensive data base of pier-scour measurements has been developed over the last several years in cooperative studies between state highway departments, the Federal Highway Administration, and the U.S. Geological Survey. Selected scour processes and scour design equations are evaluated using 139 measurements of local scour in live-bed and clear-water conditions. Pier-scour measurements were made at 44 bridges around 90 bridge piers in 12 states. The influence of pier width on scour depth is linear in logarithmic space. The maximum observed ratio of pier width to scour depth is 2.1 for piers aligned to the flow. Flow depth and scour depth were found to have a relation that is linear in logarithmic space and that is not bounded by some critical ratio of flow depth to pier width. Comparisons of computed and observed scour depths indicate that none of the selected equations accurately estimate the depth of scour for all of the measured conditions. Some of the equations performed well as conservative design equations; however, they overpredict many observed scour depths by large amounts. Some equations fit the data well for observed scour depths less than about 3 m (9.8 ft), but significantly underpredict larger observed scour depths.

Maximum scour depth around bridge pier in gravel bed streams

2017 ◽  
Vol 91 (2) ◽  
pp. 819-836 ◽  
Author(s):  
Manish Pandey ◽  
P. K. Sharma ◽  
Z. Ahmad ◽  
Nilav Karna
Keyword(s):  
Bridge Pier ◽  
Scour Depth ◽  
Gravel Bed ◽  
Gravel Bed Streams

Clear-water scour at bridge piers in fine and medium gravel beds

2005 ◽  
Vol 32 (4) ◽  
pp. 775-781 ◽  
Author(s):  
Rajkumar V Raikar ◽  
Subhasish Dey
Keyword(s):  
Bridge Piers ◽  
Geometric Standard Deviation ◽  
Scour Depth ◽  
Size Factor ◽  
Clear Water ◽  
Envelope Curve ◽  
Gravel Beds ◽  
Sediment Size ◽  
Gravel Size ◽  
Equilibrium Scour Depth

An experimental investigation on scour at circular and square piers in uniform and non-uniform gravels (fine and medium sizes) under clear-water scour at limiting stability of gravels is presented. From the experimental results, it is observed that the equilibrium scour depth increases with decrease in gravel size. The variation of equilibrium scour depth with gravel sizes departures considerably from that with sand sizes. Consequently, the resulting sediment size factors for gravels, obtained from envelope curve fitting, are significantly different from the existing sediment size factor for sands. The influence of gravel gradation on scour depth is also prominent in non-uniform gravels. The time scales to represent the time variation of scour depth in uniform and non-uniform gravels are determined. For uniform gravels, the non-dimensional time scale increases with increase in pier Froude number and gravel size, whereas for non-uniform gravels, it decreases with increase in geometric standard deviation of particle size distribution of gravels.Key words: bridge pier, gravel beds, scour, erosion, sediment transport, open channel flow, hydraulic engineering.

Estimating Equilibrium Scour Depth at Cylindrical Piers in Experimental Studies

2011 ◽  
Vol 137 (9) ◽  
pp. 1089-1093 ◽  
Author(s):  
Gonzalo Simarro ◽  
Cristina M. S. Fael ◽  
António H. Cardoso
Keyword(s):  
Experimental Studies ◽  
Scour Depth ◽  
Equilibrium Scour Depth

scholarly journals Physical model study of bedrock scour downstream of dams due to spillway plunging jets

2020 ◽  
Vol 62 (3) ◽  
Author(s):  
A Bosman ◽  
G R Basson
Keyword(s):  
Physical Model ◽  
Linear Regression Analysis ◽  
Scour Depth ◽  
Model Study ◽  
Fissured Rock ◽  
Scour Hole ◽  
Plunging Jets ◽  
Concrete Blocks ◽  
Rock Bed ◽  
Equilibrium Scour Depth

The erosive power of a free-falling high-velocity water jet, flowing from a dam spillway, could create a scour hole downstream of the dam, endangering the foundation of the dam. Despite extensive research since the 1950s, there is presently no universally agreed method to predict accurately the equilibrium scour depth caused by plunging jets at dams. These formulae yield a large range of equilibrium scour dimensions. The hydrodynamics of plunging jets and the subsequent scour of a rectangular, horizontal and vertical fissured rock bed were investigated in this study by means of a physical model. Equilibrium scour hole geometries for different fissured dimensions (simulated with rectangular concrete blocks tightly prepacked in a regular rectangular matrix), for a range of flow rates, plunge pool depths, and dam height scenarios were experimentally established with 31 model tests. From the results, non-dimensional formulae for the scour hole geometry were developed using multi-linear regression analysis. The scour depth results from this study were compared to various analytical methods found in literature. The equilibrium scour hole depth established in this study best agrees with that predicted by the Critical Pressure method.

Use of Laboratory and Field Data to Evaluate the Pier Scour Equation from Hydraulic Engineering Circular 18

2017 ◽  
Vol 2638 (1) ◽  
pp. 113-121
Author(s):  
Stephen T. Benedict ◽  
Thomas P. Knight
Keyword(s):  
South Carolina ◽  
Field Data ◽  
Field Measurements ◽  
The United States ◽  
Prediction Equation ◽  
Hydraulic Engineering ◽  
Bridge Engineering ◽  
Geological Survey ◽  
Pier Scour ◽  
Primary Focus

The Hydraulic Engineering Circular 18 (HEC-18) pier scour prediction equation is the most widely used pier scour prediction equation in the United States, if not the world, and understanding the equation’s performance is of interest to the bridge engineering community. Previous evaluations of the equation’s performance were limited to smaller sets of laboratory and field data. In 2014, the U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, published a U.S. Geological Survey pier scour database, consisting of 569 laboratory and 1,858 field measurements of pier scour. This extensive database is a valuable resource for evaluating the HEC-18 pier scour equation, which is the primary focus of the investigation presented in this paper. Although comparing predicted and measured values is a common method for evaluating the performance of a prediction equation, the present investigation used a different approach and evaluated the HEC-18 equation by comparing selected data from the USGS database with the dimensionless relationship used to develop the original equation. This alternative approach highlighted some of the strengths and weaknesses of the equation, which are not as evident in the more common approach of comparing predicted and measured values. The findings of the investigation are presented in this paper.

Breaking from the average: Why large grains matter in gravel-bed streams

2018 ◽  
Vol 43 (15) ◽  
pp. 3190-3196 ◽  
Author(s):  
Lucy G. MacKenzie ◽  
Brett C. Eaton ◽  
Michael Church
Keyword(s):  
Gravel Bed ◽  
Gravel Bed Streams

Experimental investigation of the equilibrium scour depth below submerged pipes both in live-bed and clear-water regimes under the wave effect

2018 ◽  
Vol 80 ◽  
pp. 49-56 ◽  
Author(s):  
Mustafa Dogan ◽  
Aysegul Ozgenc Aksoy ◽  
Yalcin Arisoy ◽  
Mehmet Sukru Guney ◽  
Vahid Abdi
Keyword(s):  
Experimental Investigation ◽  
Scour Depth ◽  
Clear Water ◽  
Wave Effect ◽  
Water Regimes ◽  
Equilibrium Scour Depth
Sign in / Sign up

Export Citation Format

Share Document