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新建赤峰至京沈高铁喀左站铁路工程跨越老哈河。为研究工程对河道行洪的影响,应用MIKE21模型模拟建桥后的河道水流,进而进行防洪影响评价。根据老哈河上游4处参证水文站推求桥址处设计洪水。采用RIEGL三维激光扫描仪测量河道地形,结合1:1万地形图处理后,采用三角形网格对计算区域进行网格划分。对糙率等参数率定后,采用MIKE21模型进行模拟计算。计算结果表明,老哈河铁路桥修建后壅水高度较小,流场变化不大,对河道行洪安全影响较小。实践证明应用MIKE21模型模拟河道水流其效果良好,合理的评价结果为工程的防洪安全提供了保障。在实践中应做好对糙率等参数的率定,以保证模型的正确运行。 相似文献
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山区河道弯曲狭长,洪水期峰高流急,而受地形和线位制约,很多桥梁不得不采用斜交方式跨河,进一步增加了阻水面积,给河道防洪造成很大压力。以拟建兰江特大桥为例,通过二维数值模型计算分析斜交桥梁扭转桥墩和增大桥跨两种结构优化方案对山区河道防洪和河床冲刷的影响效果。结果表明:扭转桥墩轴线与水流方向平行可以减小斜交桥梁对河流的阻水效应,并且可以改善桥墩的挑流作用,减小河道冲刷;增大桥跨(减少桥墩阻水面积)也是减轻桥梁阻水的有效措施,再结合扭墩对桥梁结构进行优化,可以显著减轻桥梁阻水作用,改善桥墩的挑流作用,并且减轻对河道的冲刷。 相似文献
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为了确保桥梁安全,消除洪水灾害的威胁,在桥梁建设前对拟建桥梁进行细致的防洪风险分析就显得尤为重要。利用有限体积方法,结合Delaunay网格剖分方法,进行自适应网格加密,建立高效的桥梁工程防洪风险评价模型。通过桥墩周围网格局部加密的方式,维持大范围河道大尺度计算网格,从而降低网格数量,提高计算效率。模型验证通过溃坝算例说明使网格数量大幅降低的同时维持了较高的计算精度。利用数值模型对某桥梁工程进行防洪风险评价,结果表明:桥梁工程的建设使桥墩附近流速降低,桥墩间流速增大约0.5 m/s左右,桥梁上下游断面流速降低约0.2 m/s;桥梁上下游河道断面水位稍有抬升,设计洪水标准条件下桥梁上下游河道断面最高水位为540.70 m,低于桥梁底部最低高程540.94 m,拟建桥梁工程能够满足河道防洪要求。 相似文献
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李华欣 《中国水能及电气化》2019,(5)
文章以大连庄河建设大桥为案例,深入探讨了防洪影响评价内容、指标以及计算方法,分别从设计洪水、河道水力、壅水高度、河床冲刷以及梁底最低允许高度等方面综合评价了防洪影响。研究表明:大连庄河建设大桥采用平行于河道水流的桥墩布置方式,不会对河道流势产生较大影响;运用的计算方法与构建的评价体系科学、实用,能够较好地反映河道实际状况,可为其他跨河桥梁建设项目防洪影响提供一定的决策依据。 相似文献
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该文采用具有自由水面和河床切应力计算的三维数学模型分析了桥墩群对河道水流的影响。计算利用标准的k-ε紊流模型求解N-S方程得到三维流场,通过对运动方程的垂向平均积分得到求解水位的泊松方程,将该模型应用到不同收缩比条件下桥墩的绕流壅水计算,结果与物理试验值拟合较好。在实际应用中,模型比较了凉水河北京南站段桥墩群修建前后河道水位和三维流场的变化情况,分析了桥墩群对河道三维水流与水位的影响,为该段河道的整治以及规划设计提供参考。 相似文献
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为研究雅鲁藏布江流域江热桥对河道防洪的影响,基于MIKE21软件建立该研究区域的二维水动力数值模型,并对该工程的行洪水位和流场影响进行了模拟计算分析。结果表明:在10 a一遇和50 a一遇洪水条件下,工程建设引起水位最大壅高值分别为7.8 cm和9.8 cm,引起流速增加的最大值分别为0.11 m/s和0.12 m/s,工程建设不会对河道防洪和河势造成明显的不利影响。此外,对桥墩冲刷、岸坡冲刷、岸坡边坡稳定进行了计算分析,计算结果满足规范要求。研究结果可为江热桥工程项目提供防洪影响评价方面的技术支撑。 相似文献
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跨河桥梁由于在河道内布置桥墩、桥台,缩窄了天然河流行洪断面,造成桥位局部河段水位壅高,对沿河两岸防洪存在不利影响。该文以广河高速公路惠河段跨山区河流的路溪河一桥、二桥为例,采用桥墩阻水壅高计算经验公式与一维水动力数学模型,对桥墩阻水壅高值进行计算分析,并给出了经验公式适用程度的结论。 相似文献
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修建跨河桥梁直接影响河道的行洪安全,因此,有必要对跨河桥梁建设项目进行防洪影响评价。为评价通江河大桥兴建后对河道行洪可能带来的影响,建立了基于非结构网格的平面二维水流数学模型,并验证了其可靠性。采用该模型对通江河大桥工程河段进行了模拟计算,计算结果表明河段上拟建大桥的存在对河段的防洪和水流特性无明显影响,从而为该工程的审批和建设提供了有力的科学依据。 相似文献
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解刚伟 《水利水运工程学报》2014,(2):81-88
水流通过桥墩在桥墩区域形成复杂的三维流场,会对桥墩底部冲刷和桥区通航产生很大的影响,所以控制桥墩紊流区水流形态十分重要。采用RNGκ-ε紊流模型对桥墩绕流进行三维数值模拟,在墩尾设置不同长度导流板,计算分析墩周围的水流紊动强度值。设置导流板后,墩周围X/D=0~5.3断面的水流最大紊动强度值明显减小,而墩后的紊动强度普遍有减小趋势,且长度不同的导流板对同一墩型的绕流控制作用不同。合适长度的导流板能束窄紊动强度变化值σ0.1的范围,即能减小紊流宽度。 相似文献
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为研究宽浅型河道糙率和桥墩壅水对行洪能力的影响,本研究采用了物理模型试验、数值模拟和经验公式方法分别模拟其水力特性并进行比较分析。通过物理模型试验给出了河道糙率的模拟方法,分别采用4种材料模拟河道护坡:无植被、稀疏植被、稀疏植被中间种植灌木和密集植被。其中,糙率最大的密集植被和糙率最小的无植被护坡条件下各断面水位差均值为0.03 m。结果表明:对于宽浅河道,护坡糙率较大范围的变化对河道行洪能力影响不显著。复杂边界条件和水力条件下桥墩壅水模拟结果表明:二维数学模型比经验公式和一维数学模型能较真实地反映河道边界条件、桥梁长度、桥墩形状对桥墩壅水高度的影响,模拟结果同物理模型试验值较为接近。本研究为宽浅河道安全行洪中糙率评估和桥墩壅水计算提供可靠的参数和依据。 相似文献
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《水动力学研究与进展(B辑)》2015,(6)
River ice jam is one of the most important issues in rivers in cold regions during winter time. With the extra solid boundary due to the ice cover, the flow condition under ice-covered conditions is completely different from that of a open channel flow. The presence of bridge piers will further change the velocity field around the bridge piers. As a consequence, the formation and the accumulation of ice jams in the vicinity of the bridge pier will be affected. On the other side, the formation of an ice jam around the piers can cause extra turbulence to reduce the stability of a river bridge. The present study focuses on the stress analysis of the ice jam in the vicinity of a bridge pier. By developing a governing equation for describing the equilibrium state of an ice jam, the stability of the ice jam around bridge piers is analyzed and determined. As seen from the field data in literature, the stability estimations of an ice jam around bridge piers determined by the present method agree well with the field observations. Therefore, the proposed approach can be used for the prediction of the formation of ice jams around bridge piers. 相似文献
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港珠澳大桥连接香港、珠海和澳门三地,横跨珠江口水域,大桥沿线大量的桥墩和海中人工岛必将对珠江口水域的水动力环境产生影响.采用平面二维潮流数学模型模拟了建桥前后珠江口水域的水动力变化和影响程度,采用非结构网格模拟桥墩和人工岛的形状,有限体积法求解水沙控制方程.模拟结果表明,大桥工程引起的水动力变化区域主要集中在东、西人工岛上下游各5 km及非通航区桥位上下游各1 km范围以内水域,对珠江口水域的水动力分布格局基本不产生影响. 相似文献
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Experimental investigation and flow analysis of clear-water scour around pier and abutment in proximity
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Mohammad Saeed Fakhimjoo Abdollah Ardeshir Kourosh Behzadian Hojat Karami 《水科学与水工程》2023,16(1):94-105
Local scour around bridge piers and abutments is one of the most significant causes of bridge failure. Despite a plethora of studies on scour around individual bridge piers or abutments, few studies have focused on the joint impact of a pier and an abutment in proximity to one another on scour. This study conducted laboratory experiments and flow analyses to examine the interaction of piers and abutments and their effect on clear-water scour. The experiments were conducted in a rectangular laboratory flume. They included 18 main tests (with a combination of different types of piers and abutments) and five control tests (with individual piers or abutments). Three pier types (a rectangular pier with a rounded edge, a group of three cylindrical piers, and a single cylindrical pier) and two abutment types (a wing–wall abutment and a semi-circular abutment) were used. An acoustic Doppler velocimeter was used to measure the three-dimensional flow velocity for analyses of streamline, velocity magnitude, vertical velocity, and bed shear stress. The results showed that the velocity near the pier and abutment increased by up to 80%. The maximum scour depth around the abutment increased by up to 19%. In contrast, the maximum scour depth around the pier increased significantly by up to l71%. The presence of the pier in the vicinity of the abutment led to an increase in the scour hole volume by up to 87% relative to the case with a solitary abutment. Empirical equations were also derived to accurately estimate the maximum scour depth at the pier adjacent to the abutment. 相似文献
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九堡大桥建于钱塘江河口段七格弯道的弯顶。遵照重力相似、模型沙起动流速相似和水下休止角接近原则建立小比尺正态模型进行桥墩局部冲刷试验研究,预测桥墩基础的冲刷深度,分析两岸边墩对海塘的影响,为工程设计提供依据。 相似文献
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郝晋新 《水利与建筑工程学报》2020,(1):163-168
以淮南孔李淮河大桥顶推施工为工程背景,对步履式顶推施工中的临时结构设计进行研究分析。应用有限元软件MIDAS建立有限元模型,对临时墩及墩旁托架的力学性能进行计算和分析,给出最优的临时墩布置方案;在该方案基础上建立有限元全桥模型,对步履式顶推施工过程进行仿真模拟,优化导梁长度及结构形式;在最优的临时墩布置及最佳导梁结构的基础上,结合现场实测结果,探究梁拱之间不同的临时撑杆结构形式对主桥及撑杆自身的影响。结果表明:针对淮南孔李淮河大桥顶推施工,临时墩布置宜采用方案2;选用45m的钢箱梁时结构受力与变形最理想;在梁拱之间设置临时A撑可有效提高整体结构承载能力。 相似文献
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This paper describes some details and procedural steps in the equivalent resistance (E-R) method for simplifying the pier group of the Sutong Bridge, which is located on the tidal reach of the lower Yangtze River, in Jiangsu Province. Using a two-dimensional tidal current numerical model, three different models were established: the non-bridge pier model, original bridge pier model, and simplified bridge pier model. The difference in hydrodynamic parameters, including water level, velocity, and diversion ratio, as well as time efficiency between these three models is discussed in detail. The results show that simplifying the pier group using the E-R method influences the water level and velocity near the piers, but has no influence on the diversion ratio of each cross-section of the Xuliujing reach located in the lower Yangtze River. Furthermore, the simplified bridge pier model takes half the calculation time that the original bridge pier model needs. Thus, it is concluded that the E-R method can be use to simplify bridge piers in tidal river section modeling reasonably and efficiently. 相似文献