Download or read book Flow and Pressure Scour Analysis of an Open Channel Flow Having an Inundated Bridge Deck Under Various Flooding Conditions written by Bishwadipa Das Adhikary and published by . This book was released on 2008 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bridge Pressure Flow Scour for Clear Water Conditions written by U.s. Department of Transportation and published by CreateSpace. This book was released on 2015-03-10 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridges are a vital component of the transportation network. Evaluating their stability and structural response after a flood event is critical to highway safety. Bridge studies are usually designed with an assumption of an open channel flow condition, but the flow regime can switch to pressure flow when the downstream edge of a bridge deck is partially or totally submerged during a large flood. Figure 1 shows a bridge undergoing partially submerged flow in Salt Creek, NE, in June 2008. Figure 2 shows a totally submerged flow in Cedar River, IA, in June 2008, which interrupted traffic on I-80. Unlike open channel flows, these pressure flows create a severe scourability potential because scouring the channel bed is one of the only ways to dissipate the energy when passing a given discharge in pressurized flow. Although most bridge scour events are due to live bed scour, a maximum scour depth often results from clear water flows with a critical approach velocity for bedload motion. For bridge safety, this report emphasizes the equilibrium maximum scour of pressure flows in extreme clear water conditions. The objectives of the study were to collect a detailed high-quality dataset of pressure flow scour at a model bridge and to develop an analytical solution for pressure flow scour based on mass and energy conservation laws. To these ends, existing results in the literature were reviewed, and knowledge gaps were identified. Next, a series of flume experiments were conducted to examine the existing methods and test new hypotheses on bridge pressure flow scour. After, bridge flows were divided into three cases, and the mass and energy conservation laws were applied to each case, leading to hypotheses for pressure flow scour predictions. The hypotheses were tested with the flume data. In this report, an example procedure for calculating the maximum scour depth and scour profile is presented along with recommended research needs.
Download or read book Submerged Flow Bridge Scour Under Clear Water Conditions written by U.s. Department of Transportation and published by CreateSpace. This book was released on 2015-03-10 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pressure flow (also known as vertical contraction) scour occurs when a bridge deck is insufficiently high such that the bridge superstructure becomes a barrier to the flow, causing the flow to vertically contract as it passes under the deck. A bridge deck is considered partially submerged when the lowest structural element of the bridge is in contact with the flowing water but the water is not sufficiently high to overtop the bridge deck. It is considered fully submerged when a portion of the flow overtops the bridge deck. Pressure flow generally only occurs in extreme flood events, but these types of events are relevant for estimation of scour. When flow is sufficiently high so that it begins to approach the elevation of the bridge deck, some of the flow may be diverted laterally to the bridge approaches. Since the bridge approaches are often lower than the bridge deck, this diversion may reduce the scour potential under the bridge. Designers must evaluate the effects of scour under the bridge as well as potential damage caused by flow diversion. An experimentally and numerically calibrated scour model was developed in this study to calculate the maximum clear water scour depth in non-cohesive bed materials under different deck inundation conditions. The theoretical formulation of the model is based on the conservation of mass of the water passing underneath the bridge deck. Particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations were used to validate assumptions used in the derivation and verify calibration of parameters included in the scour model. As one of the important parameters in the pressure flow scour model, the separation zone thickness in the bridge opening was formulated analytically, calibrated experimentally, and verified by PIV and CFD analyses. The maximum scour depth was calculated by identifying the total bridge opening that resulted in the average velocity in the opening that is equal to the critical velocity of the bed material. This report summarizes a literature review on pressure scour and describes the physical and theoretical foundation for the model formulation. The newly collected flume data as well as PIV and CFD analyses are summarized. The model formulation is refined, tested, and compared to other approaches used to estimate pressure scour. Recommendations for model application are also provided.
Download or read book Bridge Pressure Flow Scour for Clear Water Conditions written by and published by . This book was released on 2009 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The equilibrium scour at a bridge caused by pressure flow with critical approach velocity in clear-water simulation conditions was studied both analytically and experimentally. The flume experiments revealed that (1) the measured equilibrium scour profiles under a bridge are more or less consistent across the channel width; (2) all the measured scour profiles can be described by two similarity equations where the horizontal distance is scaled by the deck width and the local scour is scaled by the maximum scour depth; (3) the maximum scour position is located under the bridge and at a location approximately 15.4 percent of the deck width from the downstream edge of the deck; (4) scour begins at approximately one deck width upstream of the bridge, and deposition begins at approximately 2.5 deck widths downstream of the bridge; and (5) the maximum scour depth decreases with increasing median sediment size but increases with higher levels of deck inundation. The analytical analysis shows that (1) bridge scour can be divided into three cases: downstream unsubmerged, partially submerged, and totally submerged; (2) for downstream unsubmerged flows, the maximum scour depth is an open channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied; and (3) for partially and totally submerged flows, the maximum scour depth can be described by scour and inundation similarity numbers, which has been confirmed by experiments with two sediment sizes (0.039 and 0.078 inches (1 and 2 mm)) and two types of decks with three and six girders, respectively. For application, a design and field evaluation procedure with examples is presented, including the maximum scour depth and scour profile.
Download or read book Submerged Flow BrIdge Scour Under Clear Water Conditions written by Zhaoding Xie and published by . This book was released on 2012 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Prediction of pressure flow (vertical contraction) scour underneath a partially or fully submerged bridge superstructure in an extreme flood event is crucial for bridge safety. An experimentally and numerically calibrated formulation is developed for the maximum clear water scour depth in non-cohesive bed materials under different approach flow and superstructure inundation conditions. The theoretical foundation of the scour model is the conservation of mass for water combined with the quantification of the flow separation zone under the bridge deck superstructure. In addition to physical experimental data, particle image velocimetry measurements and computational fluid dynamics simulations are used to validate assumptions used in the derivation of the scour model and to calibrate parameters describing the separation zone thickness. With the calibrated model for the separation zone thickness, the effective flow depth (contracted flow depth) in the bridge opening can be obtained. The maximum scour depth is calculated by identifying the total bridge opening that creates conditions such that the average velocity in the opening, including the scour depth, is equal to the critical velocity of the bed material. Data from previous studies by Arneson and Abt and Umbrell et al. are combined with new data collected as part of this study to develop and test the proposed formulation."--Technical report documentation p.
Download or read book Submerged Flow BrIdge Scour Under Clear Water Conditions written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Prediction of pressure flow (vertical contraction) scour underneath a partially or fully submerged bridge superstructure in an extreme flood event is crucial for bridge safety. An experimentally and numerically calibrated formulation is developed for the maximum clear water scour depth in non-cohesive bed materials under different approach flow and superstructure inundation conditions. The theoretical foundation of the scour model is the conservation of mass for water combined with the quantification of the flow separation zone under the bridge deck superstructure. In addition to physical experimental data, particle image velocimetry measurements and computational fluid dynamics simulations are used to validate assumptions used in the derivation of the scour model and to calibrate parameters describing the separation zone thickness. With the calibrated model for the separation zone thickness, the effective flow depth (contracted flow depth) in the bridge opening can be obtained. The maximum scour depth is calculated by identifying the total bridge opening that creates conditions such that the average velocity in the opening, including the scour depth, is equal to the critical velocity of the bed material. Data from previous studies by Arneson and Abt and Umbrell et al. are combined with new data collected as part of this study to develop and test the proposed formulation."--Technical report documentation page
Download or read book Open Channel Flow written by M Hanif Chaudhry and published by Springer Science & Business Media. This book was released on 2007-12-04 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Open Channel Flow, 2nd edition is written for senior-level undergraduate and graduate courses on steady and unsteady open-channel flow. The book is comprised of two parts: Part I covers steady flow and Part II describes unsteady flow. The second edition features considerable emphasis on the presentation of modern methods for computer analyses; full coverage of unsteady flow; inclusion of typical computer programs; new problem sets and a complete solution manual for instructors.
Download or read book Open Channel Flow written by Subhash C. Jain and published by John Wiley & Sons. This book was released on 2000-10-24 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: In diesem Band geht es um Strömungen, deren Oberfläche gegenüber der Atmosphäre offenliegt - etwa in Kanälen, Flüssen, Kanalisationsrohren und manchen Abwasserleitungen. Bau- und Umweltingenieuren wird erläutert, wie sich das Wasser in diesen Situationen verhält; alle Gleichungen werden sowohl in algebraischer als auch in Differentialform gelöst. Eine wertvolle Hilfe bei der Konstruktion von Kanalsystemen! (11/00)
Download or read book Transportation Research Record written by and published by . This book was released on 1998 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Open Channel Flow written by Glenn E. Moglen and published by CRC Press. This book was released on 2015-04-17 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Exposes You to Current Industry-Standard ToolsOpen channel flow is covered in essentially all civil and environmental engineering programs, usually by final-year undergraduate or graduate students studying water resources.Fundamentals of Open Channel Flow outlines current theory along with clear and fully solved examples that illustrate the concept
Download or read book Laboratory Test of Scour Under Ice written by Decker Hains and published by . This book was released on 2004 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Open Channel Flow written by MADAN MOHAN DAS and published by PHI Learning Pvt. Ltd.. This book was released on 2008-07-11 with total page 359 pages. Available in PDF, EPUB and Kindle. Book excerpt: Primarily intended as a textbook for the undergraduate and postgraduate students of civil engineering, this book provides a comprehensive knowledge in open channel flow. The book starts with the concept of open channel flow, types of forces acting on the flow, types of channel flow, velocity distribution and coefficients, and basic continuity in 1D and 3D. Then it moves on to steady gradually varied flow, its differential equation, hydraulics of alluvialchannel, design of channel and hydraulic jump. Finally, the text concludes with Saint-Venant equations and its solutions by few numerical methods in flood routing and dam-break situations. KEY FEATURES : Includes computer programs for steady gradually varied flow Provides various numerical methods of solving the equations Explains dam-break problem in detail Contains numerous solved examples
Download or read book Guide to Bridge Hydraulics written by Transportation Association of Canada and published by Thomas Telford. This book was released on 2004 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Basic hydraulic considerations - Channel types and behaviour relation to bridges - Basic hydraulic requirements - Hydraulic design procedures Hydrologic estimates - Statistical frequency analysis - Runoff modeling - Empirical methods - High water levels and stage-discharge relations - Extreme floods and risk Scour protection and channel control - Scour protection around bridge foundations - Erosion protection of banks and slopes - Design of rock riprap - Cannel control works Hydraulic aspects of construction, inspection and maintenance - Construction - Inspection - Maintenance Special problems - Tidal crossings - Inland basic crossings - Waves and waves protection - Physical modeling of bridge problems - Alluvial fans - Debris flow and torrents
Download or read book Prediction of Clear water Abutment Scour Depth in Compound Channel for Extreme Hydrologic Events written by SeungHo Hong and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Extreme rainfall events associated with global warming are likely to produce an increasing number of flooding scenarios. A large magnitude of hydrologic events can often result in submerged orifice flow (also called pressure flow) or embankment and bridge overtopping flow, in which the foundation of a bridge is subjected to severe scour at the sediment bed. This phenomenon can cause bridge failure during large floods. However, current laboratory studies have focused on only cases of free-surface flow conditions, and they do not take bridge submergence into account. In this study, abutment scour experiments were carried out in a compound channel to investigate the characteristics of abutment scour in free-surface flow, submerged orifice flow, and overtopping flow cases. Detailed bed contours and three components of velocities and turbulent intensities were measured by acoustic Doppler velocimeters. The results show that the contracted flow around an abutment because of lateral and/or vertical contraction and local turbulent structures at the downstream region of the bridge are the main features of the flow responsible for the maximum scour depth around an abutment. The effects of local turbulent structures on abutment scour are discussed in terms of turbulent kinetic energy (TKE) profiles measured in a wide range of flow contraction ratios. The experimental results showed that maximum abutment scour can be predicted by a suggested single relationship even in different flow types (i.e., free, submerged orifice, and overtopping flow) if the turbulent kinetic energy and discharge under the bridge can be accurately measured.
Download or read book The Effects of Pressure Flow on Local Scour in Bridge Openings written by Larry A. Arneson and published by . This book was released on 1997 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Local Scouring Phenomenon at Bridge Abutments Terminating in the Floodplain Zone written by Salah Kouchakzadeh and published by . This book was released on 1996 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study examines the local scouring phenomenon associated with bridge abutments exposed to combined main-channel (MC) and floodplain (FP) flows. The principal goal of the study was to develop and validate, based on a comprehensive physical-model testing programme that considered different abutment shapes, an improved relationship for predicting maximum scour depth. A relationship was established among sediment size, flow depth and longitudinal channel slope for initiating the threshold condition of bed material movement. This relationship facilitated the selection of sediment size and channel bed slope for the various experiments, which were performed in a compound channel under interacting (combined MC and FP flows) and non-interacting (isolated FP flow) conditions. Clear-water approach-flow conditions were utilized throughout the testing programme. A flow visualization technique was employed to study the various patterns of the combining flows in the MC/FP junction regions. It determined both the flow deflection angle and the extent of the influence zone (a portion of the channel width beyond the abutment) whose discharge, $Q\sb{w}$, contributes to the scour development. Maximum scour depths produced under interacting conditions were observed to be 15% to 30% greater than those observed for non-interacting conditions. This important observation clearly demonstrated the need to properly account for compound-channel effects in the simulation exercise. The scour prediction relationship presented herein is based on a dimensional analysis of the relevant parameters and incorporates the data obtained from the laboratory studies performed in a compound channel using vertical-wall, wing-wall, semi-circular, and spill-through abutment shapes. The model indicates a very good agreement between predicted and observed maximum scour depths for bridge abutments terminating in the FP zone.
Download or read book Reaeration in Open channel Flow written by J. P. Bennett and published by . This book was released on 1972 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt: An evaluation of procedures for measuring and predicting the reaeration coefficient of open channel flows.
