共查询到18条相似文献,搜索用时 203 毫秒
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《水道港口》2021,42(4)
东海大桥是上海国际航运中心洋山深水港工程的重要组成部分。据实测显示,自大桥建成后,部分桥墩周围发生了明显的局部冲刷现象,最大冲刷深度已达到或稍超出设计时预估的冲刷深度。为确保桥梁安全运营,对桥墩实施防护工程是非常必要的。文章采用物理模型试验方法,研究了波浪和水流组合作用下典型桥墩防护方案护底结构稳定性。研究结果表明:100 a重现期波浪(H_s=5.12 m,T=10.5 s)与最大可能流速(1.98 m/s)共同作用下,对底床形成有效防护需要25 000个钩连体,对于混凝土联锁块软体排方案,需要辅助压脚结构,其中网箱石笼结构的受力性能好,材料利用率高。 相似文献
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为改善港内水域平稳度,本文采用Fluent软件建立桩基挡板透空堤与潜堤的数值波浪水槽联合模型,在设计高水位及2年一遇波浪组合下,计算潜堤断面尺度(坡比、堤顶宽度、堤身高度)和潜堤位置变化的120组试验工况,研究潜堤的消浪特性,得到潜堤位于距透空堤1/6波长位置与潜堤高度2.5 m能够改善水域平稳度,满足堤后H4%波高均小于0.6 m。 相似文献
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潮汐河段桥墩局部冲刷深度的试验研究 总被引:1,自引:0,他引:1
随着公路延伸到潮汐河道和近海海港,在桥梁设计中需要对潮汐河段桥墩的局部冲刷深度进行分析。在动床模型试验中使用了典型的潮汐水流条件和3种代表性的模型沙。使用拍照和测量记录下冲刷坑的形态和深度变化过程,得到了潮汐河段桥墩的冲刷过程,将潮流冲刷的深度与恒定流的深度进行比较,得出不同条件下冲刷深度的折减系数为0.75~0.92,建议以涨落急最大流速代替恒定流流速作为计算的标准,试验结果还表明泥沙粒径小于0.15 mm条件下的公式计算结果与试验结果有差别,建议对公式进行修正。 相似文献
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Experimental investigation on scour development and scour protection for offshore converter platform
Local scour around the offshore converter platform caused by current and wave will lead to the instability of foundation. A series of experiments are performed to investigate the scour development and scour protection of the offshore converter platform. The development and evolution characteristics of the local scour around the gravity based structure foundation under the actions of current flow and wave are analyzed. The results show that the edge scour mainly occurs at the lateral sides of the platform and the scour pits are symmetrical about the centerline of the platform in the streamwise flow direction. The scour depth around the gravity based structure increases with the increase of flow velocity. The inclination and collapse of the platform is observed at α = 90° and U0 = 0.25 m/s. The sand ripples are observed around the gravity based structure under the wave action, and the scour depth increases with the increase of wave height and wave period. Based on the comparisons of different scour protection methods, the combined bionic grass-geotextile-riprap protection has the best scour protection efficiency for the offshore converter platform. 相似文献
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The present study examines scour geometry and turbulent flow characteristics around circular and oblong piers in alluvial channel with downward seepage. Experiments were conducted in plane sand bed of non-uniform sand under no seepage, 10% seepage and 15% seepage conditions. Scour depth at oblong pier is significantly lesser than the scour depth at circular one.However, the scour depth at both piers reduces with downward seepage. The measurements show that the velocity and Reynolds stresses are negative near the bed at upstream of piers where the strong reversal occurs. At downstream of oblong pier near the free surface, velocity and Reynolds stresses are less positive; whereas, they are negative at downstream of circular pier. The streamline shape of oblong pier leads to reduce the strength of wake vortices and consequently reversal flow at downstream of pier. With application of downward seepage turbulent kinetic energy is decreasing. The results show that the wake vortices at oblong pier are weaker than the wake vortices at circular pier. The strength of wake vortices diminishes with downward seepage.The Strouhal number is lesser for oblong pier and decreases with downward seepage for both oblong and circular piers. 相似文献
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The present study examines scour geometry and turbulent flow characteristics around circular and oblong piers in alluvial channel with downward seepage. Experiments were conducted in plane sand bed of non-uniform sand under no seepage, 10% seepage and 15% seepage conditions. Scour depth at oblong pier is significantly lesser than the scour depth at circular one. However, the scour depth at both piers reduces with downward seepage. The measurements show that the velocity and Reynolds stresses are negative near the bed at upstream of piers where the strong reversal occurs. At downstream of oblong pier near the free surface, velocity and Reynolds stresses are less positive; whereas, they are negative at downstream of circular pier. The streamline shape of oblong pier leads to reduce the strength of wake vortices and consequently reversal flow at downstream of pier. With application of downward seepage turbulent kinetic energy is decreasing. The results show that the wake vortices at oblong pier are weaker than the wake vortices at circular pier. The strength of wake vortices diminishes with downward seepage. The Strouhal number is lesser for oblong pier and decreases with downward seepage for both oblong and circular piers. 相似文献
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基于水文泥沙测验及遥感影像资料分析海南岛西南海域泥沙特征,采用不同沿岸输沙公式对比计算海域的波浪沿岸输沙量,采用多年实测地形数据研究岸滩的演变规律。结果表明:海域内含沙量大潮大于小潮,但总体上悬沙含量较低;研究海域内径流对输沙影响较为有限,但受沿岸波流输沙的影响相对较大;而海区的悬移质颗粒比较均匀,颗粒较细;沿岸段波浪沿岸输沙能力净输沙方向均为自南向北,年净输沙能力在6.72万~13.31万m~3;岸滩演变的主要动力是波浪、波生沿岸流和潮流共同作用导致东方市所辖岸线的变化总体以自然冲淤变化为主,但冲淤强度有限,变化幅度不大。 相似文献
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ZHUANG Yuan LIU Zu-yuan 《船舶与海洋工程学报》2007,6(1):53-57
At present, the method of calculating the turbulent flow width around the bridge pier is not given in the "Standard for Inland River Navigation" (GB50139-2004) in China, and the bridge designer usually increases the bridge span in order to ensure the navigation safety, which increases both of the structural design difficulty and the project investments. Therefore, it is extremely essential to give a research on the turbulent flow width around the bridge pier. Through the experiments of the fixed bed and the mobile bed, the factors influencing the turbulent flow width around the bridge pier have been analyzed, such as the approaching flow speed, the water depth, the angles between the bridge pier and the flow direction, the sizes of bridge pier, the shapes of the bridge pier, and the scouring around the bridge pier, etc. Through applying the dimension analytic method to the measured data, the formula of calculating the turbulent flow width around the bridge pier is then inferred. 相似文献
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In this work, experimental investigations have been pursued to analyse the influence of downward seepage on the turbulent characteristics of flow and corresponding changes in vortex structure around circular bridge pier in alluvial channel. Experiments were conducted in sand bed channel with circular piers of different sizes for no seepage, 10% seepage and 20% seepage cases. The measurement of turbulent flow statistics such as velocity and Reynolds stresses is found to be negative within the scour hole at upstream of the pier whereas application of downward seepage retards the reversal of the flow causing a decrement in the velocity and Reynolds stresses. Higher Reynolds shear stress prevails at the downstream side because of the production of wake vortices. Contribution of all bursting events to the total Reynolds shear stress production has been observed to increase with downward seepage. The analysis of integral scale suggest that size of eddies increases with seepage, which is responsible for increase in particle mobility. Initially rate of scouring is more which abatements gradually with expanding time as well as with the increased of downward seepage. Presence of downward seepage reduces the depth and length of vortex and shifts towards downstream side of the pier. 相似文献