Download or read book Flow and Erosion Around Bridge Piers microform written by Ferdous Ahmed and published by National Library of Canada = Bibliothèque nationale du Canada. This book was released on 1995 with total page 347 pages. Available in PDF, EPUB and Kindle. Book excerpt: The structure of the flow and erosion around circular cylinders were investigated experimentally. Smooth and sand bed runs (with and without scour holes) were performed to study the effect of roughness and scour holes on the flow. Detailed measurements of velocity, pressure, bed shear stress and scour profiles were made.

Download or read book Effects of Debris on Bridge Pier Scour written by Peter Frederick Lagasse and published by Transportation Research Board. This book was released on 2010 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: TRB's National Cooperative Highway Research Program (NCHRP) Report 653: Effects of Debris on Bridge Pier Scour explores guidelines to help estimate the quantity of accumulated, flow event debris, based on the density and type of woody vegetation and river bank condition upstream and analytical procedures to quantify the effects of resulting debris-induced scour on bridge piers. The debris photographic archive, the survey questionnaire and list of respondents, and the report on the field pilot study related to development of NCHRP 653 was published as NCHRP Web-Only Document 148: Debris Photographic Archive and Supplemental Materials for NCHRP Report 653.

Download or read book Flow Investigation Around Bridge Pier on a Scoured Bed written by Md. Akhtaruzzaman Sarker and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scouring Around a Cylindrical Bridge Pier Under Partially Ice covered Flow Condition written by Adrian Munteanu and published by . This book was released on 2004 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bridge Piers as Channel Obstructions written by David Leroy Yarnell and published by . This book was released on 1934 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pier Streamlining as a Bridge Local Scour Countermeasure and the Underlying Scour Mechanism written by Junhong Li and published by . This book was released on 2018 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridge local scour has long been identified as the most critical cause to bridge failures. Countermeasures that are commonly used nowadays still have disadvantages to some extent. This work is among one of the ongoing efforts to explore reliable alternatives. Inspired by the streamlined body of boxfish and blue shark, this study introduced streamlining features to the bridge piers in order to reduce the erosive forces locally. Based on the excess shear stress criteria, the Reynolds-Averaged Navier Stokes (RANS) numerical model was employed to optimize the streamlined features through parametric studies. The maximum bed shear stress around the optimal streamlined pier was shown to be reduced by ~34% as compared to that around a non-streamlined pier. Further simulation using the advanced Detached Eddy Simulation (DES) model revealed that the streamlined pier also helped reduce the locally turbulence dynamics, which played a significant role in local scour. A set of small-scale flume tests were then conducted in the laboratory to characterize the flow physics and scour behavior of uniform Ottawa sand around piers with various streamlined extents. The experimental results further confirmed the effectiveness of pier streamlining in scour reduction. The maximum scour depth around the streamlined pier was reduced by ~66% as compared to that around a non-streamlined pier. Through monitoring the pore pressure response within sand, the role of vortex-induced excess pore pressure that plays in the scour mechanism was discussed. The vortex-induced excess pore pressure also helped to partially account for an interestingly counterintuitive observation from an independent experiment: the local scour resistance was a slightly decreasing function of the granular bulk density. Finally, a CFD-DEM (Discrete Element Model) two-way coupled model was established to simulate the scour behavior of uniform spherical particles around an oblong pier. The two-phase model successfully captured the characteristic local scour behaviors, and thus may serve as a platform of great potential to further investigate the scour mechanism at microscale in the future. Tremendous efforts were also made to review applications of the emerging two-phase numerical models to the broad flow-induced erosion problems.

Download or read book Prediction of Turbulent Flow and Scour Around Bridge Piers written by Shaghayegh Pournazeri and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The prevention and control of bridge scour is a challenging element in bridge-pier foundation design. Sediment scour from around the piers has been a main cause of all bridge failures. For the cost-effective and reliable design of pier foundations, one needs accurate prediction of flow-inducing scour. Such prediction can be obtained from numerical modelling, as a good extension of experimental results. General CFD software packages are incapable to simulate sediment transport (bedload) and bed-level change (scour/deposition). Some numerical models have been developed for bedload and scour simulations, but there are two major limitations: (1) the bed sediments are assumed to have uniform grain size which is not true in natural river channels; (2) the modelling techniques are not computationally efficient for applications at the field scale. Thus, new modelling techniques for scour prediction are needed.The objectives of this research are: (1) to modify an existing shallow-water hydrodynamics model to allow for non-hydrostatic pressure corrections; (2) to improve the prediction of bed shear stress, a key parameter for bedload prediction; (3) to incorporate a new module for calculating bedload of mixed sediment-grain sizes; (4) to verify the model’s prediction with existing experimental data.For pressure corrections, a seven-diagonal linear system is added to the model, which is symmetric and positively defined. This system is numerically solved for non-hydrostatic pressure through preconditioned conjugate gradient iterations. Then, corrections to velocity and water surface elevation due to non-hydrostatic pressure are obtained. Fractional bedload calculations are based on a surface-based transport function, which depends on a particle-hiding factor, bed shear stress, and grain size distribution. Bed level change caused by bedload is calculated using the Exner equation added to the model.The new model successfully predicts 3-D velocities around a circular pier in a fixed scour-hole and scour development on a mobile bed with uniform and non-uniform sediments. We improve bed shear stress prediction by using near-bottom velocities, as opposed to the widely used bottom-layer velocity, in the wall function method. Velocity and scour depth predictions agree well with experimental data. We show that scour emerges from the lateral sides of a pier, and scour patterns move toward its upstream nose. On the upstream side, relative to the pier’s centre, scour depth increases until the bed slope reaches the angle of repose of sediments. On the downstream side, scour continues until equilibrium is reached. Scour is deeper on the upstream than downstream side. Non-uniformity in grain sizes tends to reduce the magnitude of scour. The presence of the pier causes a strong vortex at its foot on the upstream side, which effectively moves sediments toward downstream. On the upstream side, the scour-hole’s outer shape is almost half a cone, true for both uniform and non-uniform sediments. These findings have implications to foundation design. The modelling techniques presented in this study are computationally efficient and are practical for applications at the field scale, which have been difficult so far.

Download or read book Countermeasures to Protect Bridge Piers from Scour written by Peter Frederick Lagasse and published by Transportation Research Board. This book was released on 2007 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: Explores practical selection criteria for bridge-pier scour countermeasures; guidelines and specifications for the design and construction of those countermeasures; and guidelines for their inspection, maintenance, and performance evaluation. Produced along with the report is an interactive version of the countermeasure selection methodology, which defines the proper conditions for the use of each specific countermeasure, and a reference document that contains detailed laboratory testing results and translations of three German "Code of Practice" documents.

Download or read book Local Scour Around Bridge Piers Under Steady and Unsteady Flow Conditions written by Tony Andrew Bennetts and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Experimental and Numerical Study of Local Scour Around Side by side Bridge Piers Under Ice covered Conditions written by Mohammad Reza Namaee and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Local scour around piers and abutments is one of the main causes of the collapse of many bridges constructed inside rivers. Many researchers have conducted various studies to predict the maximum depth of a scour hole around bridge piers and abutments. However, most of them have been done in small-scale laboratory flumes and specifically for the open channel condition. Besides, most of the existing research on bridge piers uses uniform sediment which is not an appropriate representative of natural river systems. This can result in excessively conservative design values for scour in low risk or non-critical hydrologic conditions. The most severe cases of bridge pier scouring occur in cold regions when the surface of water turns into ice in which, an additional boundary layer is being added to the water surface, which leads to significant changes in the flow field and scour pattern around bridge piers. Ice cover also causes the maximum flow velocity to move closer to the channel bed.

Download or read book Scour Around Circular Bridge Piers at High Froude Numbers written by Subhash Chandra Jain and published by . This book was released on 1979 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scour Around Bridge Piers and Abutments written by Emmett Morgan Laursen and published by . This book was released on 1956 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Generalized Model Study of Scour Around Bridge Piers and Abutments written by Emmett M. Laursen and published by . This book was released on 1953 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Calculation of Bridge Pier Scour Using the Erodibility Index Method written by George Annandale and published by . This book was released on 2001 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report explains the use of the Erodibility Index Method (also known as Annandale's Method) to calculate bridge pier scour. The method can be used to predict scour in any earth material, including rock and cohesive and noncohesive soils. Earth material properties are represented by a geo-mechanical index that integrates the role of material mass strength, block/particle size, internal shear strength and orientation in quantifying the relative ability of earth material to resist scour. A relationship between the geo-mechanical index and the erosive power of water defines the scour threshold that is used in the scour calculations. By comparing the erosive power that is required to scour an earth material (obtained from the threshold relationship) with the erosive power that is available at the base of a bridge pier, it is possible to calculate scour depth. The report outlines the methods that are used to quantify the geo-mechanical index and those that are used to estimate the erosive power of water flowing around bridge piers, and explains how to calculate scour depth. Application of the method is illustrated with an example.

Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1990 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physical Modeling of Local Scour Around Complex Bridge Piers written by Seung Oh Lee and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Local scour around bridge foundations has been recognized as one of the main causes of bridge failures. The objective of this study is to investigate the relationships among field, laboratory, and numerical data for the purpose of improving scour prediction methods for complex bridge piers. In this study, three field sites in Georgia were selected for continuous monitoring and associated laboratory models were fabricated with physical scale ratios that modeled the full river and bridge cross sections to consider the effect of river bathymetry and bridge geometry. Three different sizes of sediment and several geometric scales of the bridge pier models were used in this study to investigate the scaling effect of relative sediment size, which is defined as the ratio of the pier width to the median sediment size. The velocity field for each bridge model was measured by the acoustic Doppler velocimeter (ADV) to explain the complicated hydrodynamics of the flow field around bridge piers as guided by the results from a numerical model. In each physical model with river bathymetry, the comparison between the results of laboratory experiments and the measurements of prototype bridge pier scour showed good agreement for the maximum pier scour depth at the nose of the pier as well as for the velocity distribution upstream of each bridge pier bent. Accepted scour prediction formulae were evaluated by comparison with extensive laboratory and field data. The effect of relative sediment size on the local pier scour depth was examined and a modified relationship between the local pier scour depth and the relative sediment size was presented. A useful methodology for designing physical models was developed to reproduce and predict local scour depth around complex piers considering Froude number similarity, flow intensity, and relative sediment size.

Download or read book Resistance of Bridge Piers to the Flow of Water written by Earl John Taylor and published by . This book was released on 1943 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: