Cylindrical Bridge Pier Research Articles

A review on hydrodynamics of horseshoe vortex at a vertical cylinder mounted on a flat bed and its implication to scour at a cylinder

A comprehensive review of the local scour due to vortical flow around a cylindrical bridge pier under steady current is presented in this paper. The mechanism of the formation of vortices, the size, velocity and strength of horseshoe vortex (HSV), formation of the HSV by the separation of laminar and turbulent boundary layer and the scour around a cylindrical pier due to vortices have been presented. The complexity involved in the scour-related calculations, and the scope for future research are discussed in the last section.

A theoretical analysis of the fluid–solid interactions governing the removal of woody debris jams from cylindrical bridge piers

This paper proposes a theoretical model to describe previous laboratory observations of the dynamics of debris accumulations around bridge piers of cylindrical shape. The model is based on the assumption that the observed dynamics is mainly governed by dynamic changes of the point of application of the drag force exerted on a solid body formed by debris accumulated around a pier. A phase-plane analysis of the resulting nonlinear system of ordinary differential equations shows that the model captures the main patterns observed in previous laboratory experiments, including an oscillatory motion and the removal of debris from the pier by the flow. The model provides a theoretical basis for the analysis of the conditions required for debris jams to remain stable over long periods of exposure to impinging flow. Namely, the model indicates that the stability of debris accumulations primarily depends on geometrical asymmetry and on the length of the extension downstream of the pier. The former induces the torque required to rotate the jam about the pier, while the latter produces a stabilising effect after the body rotates.

Scour Depth at Single Cylindrical Bridge Piers with Debris Jam: An Experimental Comparative Study.

Rivers may carry a considerable amount of debris during floods, and the accumulation of this debris around bridge piers can change the hydraulic behaviour of flow fields and influence scour depth development. In this study, the effect of debris jam on scour depth at cylindrical bridge piers was investigated and a comparison carried out for the main existing empirical formulas. A series of 27 tests of rectangular geometry in three different groups according to width, length, submerged depth, and blocked area were studied. The results showed that the accumulation of debris increased scour depth from 10.3% to 62.1%, 22.4% to 103.4%, and 20.7% to 139.7% as the percentage blocked area of debris increased from 2.07% to 6.2%, 5.52% to 16.55%, and 8.96% to 26.89% for groups (1), (2), and (3) respectively. The comparison of the experimental results with the most commonly used empirical formulas revealed general overestimation of scour depth with debris accumulation. The Richardson and Davis (1995) and Lagasse et al. (2009) formulas were the most acceptable methods for scour prediction under debris jams, though further study is recommended for bridge pier scour depth estimation in the presence of debris.

Characteristics of Flow Structure around Cylindrical Bridge Piers in Pressure-Flow Conditions

The emerging shift of extreme events, combined with an aging infrastructure and bridges, highlights the potential increase in the risk of damage and catastrophic failure of bridges with climate change. This article analyzes the behavior of the flow and turbulence features in proximity to bridge piers, at two different moments of the scour temporal evolution in free-surface and pressure-flow conditions. Bridge pressure-flow conditions occur when the water depth submerges a bridge deck during extreme events. A circular pier and two rectangular decks of different lengths were used for this research. All tests were carried out in clear water conditions at the sediment critical velocity. This paper studied first the rate of scour temporal evolution and scour morphologies. Second, velocity measurements were taken using a Nortek acoustic Velocimeter at 25 Hz sampling rate in both free-surface and pressure-flow conditions. The average three-dimensional flow velocities, turbulence intensities, Reynolds stress, and turbulent kinetic energy were studies for the cross section corresponding to the center of the pier. The results show that pressure flow conditions accelerate the scour rate. This rate approximately reaches twice the scour in free-surface conditions with a vertical contraction of about 17%. Flow and turbulence measurements clearly exhibit how, under pressure-flow conditions, the additional turbulence and accelerated velocity modifies the flow pattern and circulation, accelerating the scour evolution around the bridge base. While numerous studies exist for pier scour and turbulence in free-surface conditions, pressure flow conditions received limited attention in the past. These results provide essential information for understanding scour mechanisms and for facilitating the design of future structures to increase bridge safety and resilience.

Experimental Investigation of Local Scour Protection for Cylindrical Bridge Piers Using Anti-Scour Collars

Local scour of bridge piers is one of the main threats responsible for bridge damage. Adopting scour countermeasures to protect bridge foundations from scour has become an important issue for the design and maintenance of bridges located in erodible sediment beds. This paper focuses on the protective effect of one active countermeasure named an “anti-scour collar” on local scour around the commonly used cylindrical bridge pier. A cylindrical pier model was set up in a current flume. River sand with a median particle size of 0.324 mm was selected and used as the sediment in the basin. A live-bed scour experimental program was carried out to study the protective effect of an anti-scour collar by comparing the local scour at a cylindrical bridge pier model with and without collar. The effects of three design parameters including collar installation height, collar external diameter and collar protection range, on the scour depth and scour development were investigated parametrically. According to the experimental results, it can be concluded that: the application of an anti-scour collar alleviates the local scour at the pier effectively; and the protection effect decreases with an increase in the collar installation height, but increases with an increase in the collar external diameter and the protection range. Design suggestions for improving the scour protective effect of the anti-scour collar are summarized and of great practical guiding significance to the development of anti-scour collars for bridge piers.

Topographic Evolution around Twin Piers in a Tandem Arrangement

This laboratory study investigates the 2-D topographic evolution of a sand bed with cylindrical bridge piers arranged in tandem. The results of clear-water scouring experiments around two piers show that shapes of topography were similar for different spacing and scour duration. Fractal theory and statistical analysis were used to estimate the statistical properties of the evolution of the sand-bed topography around the piers. The statistical properties of the bed surface contours remained almost stationary under continuing scouring action. Finally, the difference of local scour depth between two piers with scour time can be segregated into three regions: sheltering region, co-effect region and stabilizing region.

Bed topography variations in bend by simultaneous installation of submerged vanes and single bridge pier

Every year, thousands of bridges around the world are destroyed by scouring around their piers. One of the methods to control and protect the piers against scouring is to use submerged vanes. The purpose of this paper is to investigate the effect of upstream submerged vanes on scouring around the bridge pier and bed topography changes. For doing experiments, a cylindrical bridge pier and several numbers of submerged vanes with various angles and lengths were used in a laboratory flume with a 180° sharp bend. The results illustrate that by using three submerged vanes, sediments have progressed less toward the downstream. Moreover, the surrounded rectangle on scour hole around the bridge pier has the largest and smallest dimensions in test with four submerged vanes, length of 1.5 times the pier diameter and angle of 35° relative to the tangent at the bend mid-section, and in a test with two submerged vanes, length of equal to the pier diameter, and angle of 15°, respectively.

Local scour around two side-by-side cylindrical bridge piers under ice-covered conditions

In the current study, 108 flume experiments with non-uniform, cohesionless sediments have been done to investigate the local scour process around four pairs of side-by-side bridge piers under both open channel and ice-covered flow conditions. Similar to local scour around bridge piers under open channel conditions and a single bridge pier, it was observed in the experiments that the maximum scour depth always occurred at the upstream face of the pier under ice-covered conditions. Further, the smaller the pier size and the greater the spacing distance between the bridge piers, the weaker the horseshoe vortices around the bridge piers, and, thus, the shallower the scour holes around them. Finally, empirical equations were developed to estimate the maximum scour depth around two side-by-side bridge piers under both open channel and ice-covered flow conditions.

Scour Reduction by Air Injection at a Cylindrical Bridge Pier: Experimental Determination of Optimal Configuration

AbstractTo reduce bridge scour-induced collapse, experiments were performed to determine the optimal ratio of air to water velocity values for the least amount of scour at a cylindrical bridge pier...

Characterization of horseshoe vortex in a developing scour hole at a cylindrical bridge pier

Since local scour at bridge piers in rivers and estuaries is a major cause of bridge failure, estimation of the maximum local scour depth is of great importance to hydraulic and coastal engineers. Although numerous studies that focus on scour-depth prediction have been done and published, understanding of the flow and turbulence characteristics of the horseshoe vortex that drives the scour mechanism in a developing scour hole still is immature. This study aims to quantify the detailed turbulent flow field in a developing clear-water scour hole at a circular pier using Particle Image Velocimetry (PIV). The distributions of velocity fields, turbulence intensities, and Reynolds shear stresses of the horseshoe vortex that form in front of the pier at different scour stages (t = 0, 0.5, 1, 12, 24, and 48 h) are presented in this paper. During scour development, the horseshoe vortex system was found to evolve from one initially small vortex to three vortices. The strength and size of the main vortex are found to increase with increasing scour depth. The regions of both the maximum turbulence intensity and Reynolds shear stress are found to form at a location upstream of the main vortex, where the large turbulent eddies have the highest possibility of occurrence. Results from this study not only provide new insight into the complex flow-sediment interaction at bridge piers, but also provide valuable experimental databases for advanced numerical simulations.

The Effect of Geotextile Layer in Decreasing Local Scour of Cylindrical Bridge Pier

The Effect of Geotextile Layer in Decreasing Local Scour of Cylindrical Bridge Pier

Simulations of Local Scour Around a Cylindrical Bridge Pier And a Semicircular Abutment Using Unsteady k-ε Model Combined with σ-Grid

Introduction: Bridge scour is one of the major causes of bridge failure. Prediction of the maximum depth and shape of local scour plays an important role in bridge design and maintenance. In this paper, k-ε turbulent model combined with wall function was employed and complex flow fields are exhibited. The bed load transport model summarized by Qian and Wan [1] was applied to evaluate the development of local scour. Besides, σ-grid module was developed and embedded into the commercial solver FLUENT to fit the change of channel-bed. Method: In this module, the change of the elevation of the channel bed is calculated through using user defined functions(UDF), and the motion of the grid system is realized based on a program developed through C++ language, which extends the applications of FLUENT. The evolution of local scour hole for two cases, i.e., local scour around a cylindrical pier and a semicircular abutment, was simulated. Results and Conclusion: The depth and the shape of local scour as well as the flow fields were predicted. Numerical result conforms well to the experimental measurement. Especially, it provides fairly reasonable prediction on the key issue of the maximum scour depth. The satisfactory agreement validates the numerical method developed in the present study. In addition to the validation purpose, the different performance of this method for predicting local scour around the cylindrical pier and the semicircular abutment was discussed.

Simplified Expression of Hydrodynamic Pressure on Deepwater Cylindrical Bridge Piers during Earthquakes

Simplified Expression of Hydrodynamic Pressure on Deepwater Cylindrical Bridge Piers during Earthquakes

The scour pattern around an inclined cylindrical pier in a sharp 180-degree bend: an experimental study

ABSTRACTBridge piers are highly susceptible and sensitive to scouring effects, so careful determination of scour depth can ultimately lead to more properly designed pier foundation. The goal of this study is to evaluate scour depth and location around an inclined cylindrical bridge pier in the apex of a sharp 180-degree bend, and also to compare the results with that obtained for a vertical pier. The flume used for the experiments was one metre wide and had a central radius-to-width ratio of two. The results of this study showed that the highest and the lowest scour depth were formed around the pier inclined towards the outer bank and the inner bank, respectively. The highest and lowest scour to flow depth ratios were 1.05 and 0.70 at the upstream straight path. Placing the pier with its inclination towards the outer bank led to the formation of alternating sedimentary dunes at the downstream side of the pier in an area adjacent to the inner bank. Placing the pier with its inclination towards the upstream, downstream, and inner bank led to the formation of only one sedimentary dune with a peak height of 0.60, 0.60, and 0.55 times the flow depth of the entrance section, respectively.

Experimental Study of Local Scour Depth around Cylindrical Bridge Pier

Experimental Study of Local Scour Depth around Cylindrical Bridge Pier

Prediction of time‐dependent local scour around bridge piers

AbstractMost formulas for predicting the scour depth around bridge piers result in over‐predictions. This is partly due to ignoring the fact that the local scour is a time‐dependent process. Formulas that take into account time‐dependent local scour around bridge piers have been developed in the past. However, these formulas predict the scour process well, but only when applied to datasets from which they were constructed. Motivated by this, the present study proposes a relationship for time‐dependent local scour using dimensional analysis and nonlinear regression. Similarly, another relationship for the time to equilibrium is also developed. The findings indicate that the proposed relationship predicts time‐dependent local scour better than existing formulas. The proposed relationships are applicable to local scour around cylindrical bridge piers. It is assumed that the bed sediment is uniform and the bedform effect is minor and can be ignored.

Control of the Local Scouring Around the Cylindrical Bridge Pier Using Armed Soil by Geotextile

Flood currents are considered threatening factors by creating local scour along bridge piers. One method for decreasing local scour is to strengthen the bed against imposed tensions. Among methods which can be appropriate in decreasing and controlling local scour of bridge piers directly is to put riprap beside bridge piers and to employ geotextile around them. Geotextiles form a large group of geosynthetic products produced from polypropylene and polyester fibers, and are used in separation, strengthening and reinforcing, filtration, and drainage. In the present study, the effect of geotextile layer in decreasing local scour of cylindrical single-pier was investigated and the best coverage pattern with the most effect was obtained so that layers with circular and oval shapes were put around the pier relative to its diameter, and the performance of each was compared with the unprotected pier. Test results showed by using geotextile with an appropriate cover, the scour location is transferred to downstream and the scour depth is decreased. These advantages can reduce the risk of pier failure when the duration of flood is short. The results indicate that the scour reduction increases as the layer area increased. In this case the oval layer has a better efficiency compared to the circular one.

The Effect of Groyne on Reduction of the Scour Depth around Bridge Piers in River Bends

The most important cause of concern about the stability of bridge foundation is the occurrence of scour around bridge piers. Therefore, different methods have been proposed to prevent or reduce scouring around bridge piers. The use of groynes is one of the modern methods to control and reduce local scour. In the present study, the effect of a solid groyne on reduction of the scour depth around a cylindrical bridge pier, located in the bend of a laboratory flume is assessed. Experiments were conducted for groyne model angled at 50 , 90 and 120 to the downstream channel sidewall with three flow rates of 47, 49 and 51 liters per second in a sediment free condition. Results showed that in at ratios of velocity to critical velocity and all groyne angles, in comparison with no groyne, the scour depth was reduced. At all ratios of velocity to critical velocity, the best operation was related to normal groyne and the average operation of repelling groyne was better than attracting groyne. The operation of normal groyne decreased and attracting groyne function improved as the flow rate increased. Also, the normal groyne (ratio of velocity to critical velocity equal to 0.87) had the best effect on reducing the scour depth (by about 71.4 percent).

The Effect of Collar on the Size of Proper Riprap Cover around the Cylindrical Bridge Piers in the Rivers Bend

Riprap of bridge piers is placed to eliminate local scour and to secure the pier from failure. However, riprap surfaces frequently rupture to protect bridges pier during deluges despite arrangement of riprap particles around its foundations. Improper design of proper extent for riprap cover greatly reduces the riprap efficiency in local scour control. Therefore, in this research in order to determine the proper size of riprap cover at the angle of 60° of river bend, some experiments were carried out under clean water conditions in a flume of 180°. The effect of collar presence around the pier and also different size of collar on proper size of riprap were examined in different experiments. The results showed that the presence of collar around the cylindrical bridge pier decreased the proper size of riprap as 26% compared to the pier without collar. Moreover, as the collar diameter increased, the size of riprap cover decreased which is economically affordable.

The Effect of Collar on the Size of Proper Riprap Cover around the Cylindrical Bridge Piers in the Rivers Bend

Riprap of bridge piers is placed to eliminate local scour and to secure the pier from failure. However, riprap surfaces frequently rupture to protect bridges pier during deluges despite arrangement of riprap particles around its foundations. Improper design of proper extent for riprap cover greatly reduces the riprap efficiency in local scour control. Therefore, in this research in order to determine the proper size of riprap cover at the angle of 60° of river bend, some experiments were carried out under clean water conditions in a flume of 180°. The effect of collar presence around the pier and also different size of collar on proper size of riprap were examined in different experiments. The results showed that the presence of collar around the cylindrical bridge pier decreased the proper size of riprap as 26% compared to the pier without collar. Moreover, as the collar diameter increased, the size of riprap cover decreased which is economically affordable. Keywords: Bend, Bridge, Collar, Pier, Riprap, Scour