局部冰塞体尺寸对桥墩绕流和冲刷的影响  

Influence of Size of Local Ice Jam on Flow and Scour around Bridge Piers

作　　者：刘昂 田璐 陈启刚[2] 王忠祥 徐杰梁 LIU Ang;TIAN Lu;CHEN Qi-gang;WANG Zhong-xiang;XU Jie-liang(CCCC Infrastructure Maintenance Group Co.,Ltd.,Beijing 100011,China;School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China)

机构地区：[1]中交基础设施养护集团有限公司,北京100011 [2]北京交通大学土木建筑工程学院,北京100044

出　　处：《公路交通科技》2022年第11期84-94,150,共12页Journal of Highway and Transportation Research and Development

基　　金：青海省重点研发与转化计划科技成果转化专项项目(2021-SF-161)。

摘　　要：高纬度地区河流结冰是加剧桥墩局部冲刷的潜在不利因素,为了探究墩前局部冰塞体尺寸改变对墩周水流结构及床面切应力的影响,以平床条件下圆柱墩前的局部冰塞体为研究对象,建立了三维水动力学数学模型并开展了明渠水槽物理模型试验,将试验结果与数值模拟结果进行对比,验证了数学模型的可靠性。采用数值模拟的方法分析了流凌期桥墩上游形成不同尺寸的局部冰塞体后墩周流场及床面切应力的变化规律。结果表明:冰塞体厚度是影响墩周水流结构和局部冲刷的主要变量,随着冰塞体厚度变化,墩周先后出现墩前马蹄涡、冰下回流涡和冰前马蹄涡3种显著增强床面切应力的水流结构,且墩前和墩侧仍然是床面剪切力最大的区域;定义压缩度为冰塞体厚度与水深的比值,当压缩度小于50%时,随着冰塞体厚度的增加,墩前马蹄涡位置基本不变,尺寸逐步减小,强度逐步增大,对床面起主要动力作用;当压缩度超过50%后,墩前马蹄涡迅速衰减并消失,冰下回流涡的垂向高度减小,强度迅速增大,并在压缩度超过67%后代替墩前马蹄涡对床面起主要动力作用;当压缩度大于90%后,冰下回流涡的强度迅速减弱,冰前马蹄涡垂向位置降低,强度增大,并在压缩度超过96%时对床面起主要动力作用;与不结冰河流相比,当压缩度超过67%时引起墩周床面切应力增大,对局部冲刷产生不利影响,使局部冲刷坑扩大、加深。River icing in high latitude areas is a potential adverse factor to aggravate local scour around bridge piers.To explore the influence of the size change of local ice jam in front of pier on the flow structure around pier and bed shear stress,taking the local ice jam in front of the cylindrical pier under the flat bed condition as the research object,the 3 D hydrodynamic mathematical model is established,and the physical model test of open channel flume is carried out.The experimental result is compared with the numerical simulation result,which verified the reliability of the mathematical model.The change rules of flow field and shear stress on the bed surface around the pier after the formation of different sized local ice jams upstream of the pier during ice running period are analyzed by using numerical simulation method.The result shows that(1)The ice jam thickness is the main variable affecting the flow structure and local scouring around the pier.As the thickness of the ice jam changes,there are 3 water flow structures around the pier,namely,the pier-front horseshoe vortex,the subglacial circumfluence vortex and the ice-front horseshoe vortex,which significantly enhance the bed shear stress,appear successively around the pier,and the pier-front and pier-side are still the areas with the largest bed shear force.(2)The compression degree is defined as the ratio of ice jam thickness to water depth.When the compression degree is less than 50%,with the increase of ice jam thickness,the position of the pier-front horseshoe vortex is basically unchanged,its size gradually decreases,and the strength gradually increases,which plays the main dynamic role on the bed surface.(3)When the compression degree exceeds 50%,the pier-front horseshoe vortex rapidly decays and disappears,the vertical height of the subglacial circumfluence vortex decreases,and the strength increases rapidly.When the compression degree exceeds 67%,it replaces the pier-front horseshoe vortex to play the main dynamic role on the bed surface.(4)Afte

关 键 词：桥梁工程 水流结构 数值模拟 局部冰塞体 床面切应力 局部冲刷 桥墩 

分 类 号：U442.3[建筑科学—桥梁与隧道工程]