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您的检索式：作者名="Kevin Flora"
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| 1 | Bridge Pressure Flow Scour at Clear Water Threshold Condition显示文摘Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally.The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional;all the measured scour profiles can be described by two similarity equations,where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth;the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge;the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge;and the maximum scour depth decreases with increas-ing sediment size,but increases with deck inundation.The theoretical analysis shows that:bridge scour can be divided into three cases,i.e.downstream unsubmerged,partially submerged,and totally submerged.For downstream unsubmerged flows,the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied;for partially and totally submerged flows,the equilibrium maximum scour depth can be described by a scour and an inundation similarity number,which has been confirmed by experiments with two decks and two sediment sizes.For application,a design and field evaluation procedure with examples is presented,including the maximum scour depth and scour profile. | 郭俊克 KERENYI Kornel PAGAN-ORTIZ Jorge E FLORA Kevin | 2009 | Transactions of Tianjin University2009，15，2： | 0 |
| 2 | Large-eddy simulation of flash flood propagation and sediment transport in a dry-bed desert stream显示文摘A Large-Eddy Simulation(LES)model is used to study flow dynamics of a flash flood event in a dry-bed,desert wash,the so-called Tex Wash,near the Tex Wash Bridge on Interstate 10 in the Mojave Desert of California.The evolving free surface of the flash flood is tracked using the level-set method.A bed morphodynamics module is coupled to the hydrodynamics model to calculate the erosion and bed evolution of the mobile bed of the wash under flash flood conditions.Flash floods in a desert wash can be characterized with a number of salient features such as the(1)existence of both the dry-and wet-cells on the bed surface of the wash that correspond to the air and water phases,respectively;(2)presence of various flow regimes,critical,sub-critical,and super-critical in the flow domain;and(3)occurrence of a highly transient and complicated flow field and,subsequently,sediment dynamics throughout the wash.A numerical modeling effort is presented to study a recorded flash flood and the corresponding scour processes in the Tex Wash.The flood event occurred in 2015 and lead to the collapse of the Tex Wash Bridge.The of the current study is to gain insight into the flood flow and sediment transport mechanisms,which resulted in the collapse of the bridge.To that end,a study area,which includes a 0.65 km-long reach of TexWash at its intersection with the Tex-Wash Bridge,was selected.The bathymetry of the wash was obtained using light-detection-and-ranging(LiDAR)technology and used to construct the computational domain of the wash and bridge foundations.The transient flow of the flash flood,in both air and water phases,and the evolving morphology of the wash are numerically simulated.The sitespecific numerical simulation revealed the formation of deep scour regions adjacent to the right abutment of the upstream bridge,where significant erosion caused the collapse of the bridge.Moreover,the results show that most of the scour processes take place during the steady phase of the flash flood when the desert stream is filled with water.However,the transient phase of the flash flood is rather short and contributes to a very limited amount of erosion within the stream. | Ali Khosronejad Kevin Flora Zexia Zhang Seokkoo Kang | 2020 | International Journal of Sediment Research2020，35，6： | 0 |
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