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.

Riprap Performance at Bridge Piers Under Mobile-Bed Conditions

1998 ◽  
Vol 1647 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Carlos Toro-Escobar ◽  
Richard Voigt ◽  
Bruce Melville ◽  
Meng Chiew ◽  
Gary Parker
Keyword(s):  
Experimental Tests ◽  
Bridge Piers ◽  
Design Criteria ◽  
Research Groups ◽  
Clear Water ◽  
Pier Scour ◽  
Mobile Bed ◽  
Water Conditions ◽  
Improved Design ◽  
Flood Flow

Design criteria for riprap at bridge piers in rivers is based on the specification of a size, gradation, and cover that does not fail under an appropriately chosen flood flow. Experimental tests of riprap performance at bridge piers to date have relied on a configuration for which the ambient bed is not mobilized, that is, clear-water conditions. In the field, however, riprap is, as a rule, subjected to mobile-bed conditions during floods. Recent experiments by three cooperating research groups (University of Auckland, Nanyang University, and St. Anthony Falls Laboratory) indicate a heretofore unrecognized mechanism for riprap failure under mobile-bed conditions. When the flow is in the dune regime, the passage of successive dunes causes riprap that is never directly entrained by the flow to sink and disperse. Pier scour is realized as a consequence of these processes. In some cases, the depth of scour realized is not significantly less than that which would occur without riprap. When the riprap is fully underlain by a geotextile, edge effects can cause local removal of riprap, upturning of the geotextile, and general failure. When the riprap is underlain by a partial geotextile (i.e., one that covers an area less than the riprap), edge scour causes local sinking that anchors the geotextile. The sinking and dispersion of the rest of the riprap are greatly limited, and the riprap fails only when flow velocities are sufficient for direct entrainment. The experiments suggest improved design criteria for the installation of riprap in the field.

Local scour at piled bridge piers including an examination of the superposition method

2014 ◽  
Vol 41 (5) ◽  
pp. 461-471 ◽  
Author(s):  
Ata Amini ◽  
Bruce W. Melville ◽  
Thamer M. Ali
Keyword(s):  
Bridge Piers ◽  
Prediction Methods ◽  
Scour Depth ◽  
Superposition Method ◽  
Clear Water ◽  
Laboratory Flume ◽  
Pile Cap ◽  
The Individual ◽  
Comparison Of The Results ◽  
Bed Material

An experimental investigation of clear water scour at complex piers is presented. Five complex piers, comprising different configurations of piles, pile cap, and column, were tested in a laboratory flume using uniform bed material. The piers were tested for a range of possible elevations relative to the streambed elevation. Experiments were undertaken using the complex piers and also using the individual components of each complex pier. A comparison of the results for the intact piers and for their components enabled an evaluation of the prediction methods involving superposition of scour depths at piles, pile cap, and pier column. The superposition method is found to give inadequate estimates of total scour depth in many cases.

Temporal variation of clear water scour at cylindrical bridge piers

2006 ◽  
Vol 33 (8) ◽  
pp. 1098-1102 ◽  
Author(s):  
A Melih Yanmaz
Keyword(s):  
Temporal Variation ◽  
Semiempirical Method ◽  
Bridge Pier ◽  
Bridge Piers ◽  
Recent Sediment ◽  
Clear Water ◽  
Design Flood ◽  
Pier Scour ◽  
Time To Peak ◽  
Bridge Pier Scour

Computation of temporal variation of clear water scour is important for the design of bridge pier footings. Previous studies indicated that very long flow duration was needed to achieve equilibrium scouring situations. However, the corresponding durations in the prototype conditions may yield considerably larger values than time-to-peak of the design flood. Therefore, there is a need to estimate the temporal variation of scour depth. This study deals with the development of a new semiempirical method for temporal variation of clear water scour at cylindrical bridge piers using the sediment continuity approach. A recent sediment pickup function proposed for sloping beds is used to formulate the rate of sediment transport out of the scour hole. Results of the proposed method agree well with experimental results. The findings of the proposed method are also compared with some recent empirical methods.Key words: bridge, pier, scour, clear water, sediment pickup.

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.

scholarly journals Scour Evolution Downstream of Submerged Weirs in Clear Water Scour Conditions

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1746 ◽  
Author(s):  
Dawei Guan ◽  
Jingang Liu ◽  
Yee-Meng Chiew ◽  
Yingzheng Zhou
Keyword(s):  
Coarse Sand ◽  
Analytical Models ◽  
Scour Depth ◽  
Coastal Environments ◽  
Flow Depth ◽  
Clear Water ◽  
Submerged Condition ◽  
Initial Stage ◽  
Scour Hole ◽  
Weir Height

Although weirs or dikes in the riverine and coastal environments are frequently overtopped, few studies have hitherto examined the evolution of the scour process downstream of these structures under the submerged condition. This paper presents an experimental investigation on time evolution of the scour process downstream of submerged weirs with a uniform coarse sand. The clear-water scour experiments were carried out in a tilting recirculation flume. Different flow intensities and overtopping ratios (approach flow depth/weir height) were adopted in the experiments. Experimental observations show that the scour hole downstream of submerged weirs develops very fast in the initial stage, before progressing at a decreasing rate and eventually reaching the equilibrium stage. The results show that an increase of the overtopping ratio or flowrate can generate larger scour depth and volume downstream of the weir. Moreover, geometrical similarity of the scour hole that formed downstream of the weir was observed in the tests. Finally, empirical equations for predicting scour hole geometrical evolutions downstream of the submerged weirs were presented. The results of this study are useful in the development of numerical/analytical models capable of estimating the scour depth downstream of weirs in the river or coastal areas, for which the overtopping conditions are present.

scholarly journals Optimal Octagonal Hooked Collar Countermeasure to Reduce Scour Around a Single Bridge Pier

2020 ◽  
Author(s):  
Rashid Farooq ◽  
Abdul Razzaq Ghumman ◽  
Muhammad Atiq Ur Rehman Tariq ◽  
Afzal Ahmed ◽  
Khan Zaib Jadoon
Keyword(s):  
Cross Section ◽  
Vital Role ◽  
Bridge Pier ◽  
Scour Depth ◽  
Clear Water ◽  
Action Current ◽  
Pier Scour ◽  
Uniform State ◽  
Scour Hole ◽  
New Equation

Pier modification countermeasures are essential as they play a vital role in protecting pier against local scour action. Current study investigates experimentally the scour around vertical pier of octagonal cross section with pier modification such as newly proposed octagonal hooked collar is explored, in steady uniform state, under clear water condition. The results of pier scour without any modification were used as a reference to compute the efficiency of hooked collar provision around octagonal pier. The results show that by increasing the hooked collar width up to 2.5 Wp reduced maximum scour depth significantly. However, the experimental investigation revealed that the best combination to be with a hooked collar width of 2.5 Wp, having sidewall height 0.45 Wp. The best combination minimized around 73.3 % of scour hole depth, compared to octagonal pier without any modification. Using experimental results, a new equation is proposed to predict the scour depth around a bridge pier fitted with hooked collar. Moreover, a relation was developed for maximum scour depth and scour hole volume. Results indicate that the scour hole volume around a bridge pier increases quadratically with maximum scour depth.

Experimental Study on Clear Water Scour around Bridge Piers

2011 ◽  
Vol 121-126 ◽  
pp. 162-166
Author(s):  
Yao Ming Hong ◽  
Min Li Chang ◽  
Hsueh Chun Lin ◽  
Yao Chiang Kan ◽  
Chi Chang Lin
Keyword(s):  
Flow Velocity ◽  
Large Diameter ◽  
Bridge Piers ◽  
Scour Depth ◽  
Clear Water ◽  
Experimental Conditions ◽  
Cover Depth ◽  
Sediment Cover ◽  
Equilibrium Scour Depth ◽  
Fast Flow

This study analyzed the characteristics of bridge scoured by clear water according to 14 groups of laboratory experiments. The formulation of critical velocity based on historical equations of clear water scour was concluded for the test circumstances in laboratory. The experimental conditions include the variation of flow velocity, sediment cover depth, and diameter of bridge pier/bases. The erosion status prior to the maximum scour depth was recorded by a pinhole camera, and, in general, the equilibrium scour depth was reached after 24 hours. The maximum scour depth increases as the sand cover depth decreases. As the same sediment depth, the fast flow velocity will induce the deep scour depth with respect to the slow flow velocity. The same result can be observed for the large diameter of pier (or base) versus the small one. The maximum scour depths in the front of the pier are always deeper than that behind the pier.

scholarly journals ANFIS-based approach for scour depth prediction at piers in non-uniform sediments

2009 ◽  
Vol 12 (3) ◽  
pp. 303-317 ◽  
Author(s):  
M. Muzzammil ◽  
M. Ayyub
Keyword(s):  
Fuzzy Inference ◽  
Bridge Piers ◽  
Scour Depth ◽  
Fuzzy Inference Systems ◽  
Foundation Design ◽  
Pier Scour ◽  
Depth Prediction ◽  
Alternative Approach ◽  
Inference Systems ◽  
Bridge Pier Scour

An estimation of scour depth is a prerequisite for the efficient foundation design of important hydraulic structures such as bridge piers and abutments. Most of the scour depth prediction formulae available in the literature have been developed based on the analysis of the laboratory/field data using statistical methods such as the regression method (RM). Conventional statistical analysis is generally replaced in many fields of engineering by the alternative approach of artificial neural networks (ANN) and adaptive network-based fuzzy inference systems (ANFIS). These recent techniques have been reported to provide better solutions in cases where the available data is incomplete or ambiguous by nature. An attempt has been made to compare the performance of ANFIS over RM and ANN in modeling the depth of bridge pier scour in non-uniform sediments. It has been found that the ANFIS performed best amongst all these methods.

Using field data to evaluate the complex bridge piers scour methods

2016 ◽  
Vol 43 (3) ◽  
pp. 218-225 ◽  
Author(s):  
M.H. Jannaty ◽  
A. Eghbalzadeh ◽  
S.A. Hosseini
Keyword(s):  
Field Data ◽  
Complex Geometry ◽  
Bridge Piers ◽  
Scour Depth ◽  
Laboratory Studies ◽  
Sediment Characteristics ◽  
Pier Scour ◽  
Recorded Data

Scour is a phenomenon that causes riverbed erosion. Many laboratory studies have been conducted to identify the complex geometry of the scour mechanism and to predict its depth, and various methods have been proposed. In this study, the performance of these methods in estimating scour depth was evaluated using field data. For this purpose, scour data on the Adinan Bridge, which was destroyed as a result of the scour phenomenon and consequently rebuilt, was collected. The bridge was built with complex piers. The flow and sediment characteristics for the bridge site were determined using field measurement. Then, the pier scour was calculated using the empirical formula and the calculated values were compared with the recorded data. The results showed the inefficiency of these methods in accurately estimating the scour depth. However, the role of the components of a composite pier has not been reflected properly in the determination of scour in these methods.

scholarly journals Local scour around complex pier groups and combined piles at semi-integral bridge

2014 ◽  
Vol 62 (2) ◽  
pp. 108-116 ◽  
Author(s):  
Shatirah Akib ◽  
Afshin Jahangirzadeh ◽  
Hossein Basser
Keyword(s):  
Experimental Study ◽  
Laboratory Experiments ◽  
Bridge Piers ◽  
Scour Depth ◽  
Flow Depth ◽  
Flow Discharge ◽  
Integral Bridge ◽  
Integral Bridges ◽  
Equilibrium Scour Depth ◽  
The Relationship

Abstract This research presents an experimental study on the scouring mechanism at semi-integral bridge piers. Based on laboratory experiments, this study focuses on the relationship between scour depth in complex pier groups and combined piles bridge and various parameters including the variation of inflow velocity, distance, and time. 1 200 data were collected for flow velocity and scour. The flow pattern and scour were analyzed for different flow discharges and flow depths. The results showed that the scour development with respect to time was greater for higher flow depth and bigger flow discharge at semi-integral bridges. In addition, the equilibrium scour depth increased with the approach flow depth around piers at semi-integral bridges. Velocity distribution also affected the scour development. It decreased when approaching the bridge but increased from upstream to downstream of the flume.

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