熊 文 ,张大牛
AuthorsHTML:熊 文 ^{1, 2} ，张大牛 ¹
AuthorsListE:Xiong Wen,Zhang Daniu
AuthorsHTMLE:Xiong Wen^{1, 2}，Zhang Daniu¹
Unit:1. 东南大学交通学院，南京 211189；
2. 道路交通工程国家级实验教学示范中心(东南大学)，南京 211189

Unit_EngLish:1. School of Transportation，Southeast University，Nanjing 211189，China；
2. National Demonstration Center for Experimental Road and Traffic Engineering Education (Southeast University)，Nanjing 211189，China

Abstract_Chinese:桥梁水毁具有极大突发性和破坏性，其发生机理主要为桥梁基础局部冲刷导致下部结构失稳与关键构件失 效，进而引发全桥倒塌．传统分析方法将其视为冲刷与倒塌两个独立过程进行研究，忽略两者内在的强耦合性，难 以客观真实反映桥梁水毁全过程．首先，利用 Ls-Dyna 建立基于全桥有限元模型的结构倒塌模块，设置各构件接触 条件和破坏准则，利用动态弹簧边界条件模拟局部冲刷发展；然后，利用 Fluent 建立包含推-悬移质泥沙运动的河床 床面动网格冲刷分析模块，提出一种浅基础底部冲刷形态确定方法，拟合得到反映浅基础底部掏蚀特征的河床冲刷 曲面，对该模块计算结果提取基础壁面波流应力以及基础底面掏空深度；采用 Python 建立冲刷-倒塌跨尺度界面， 使得冲刷模块关键物理量经过插值处理和换算后实时传至倒塌模块，完成冲刷-倒塌全过程的跨尺度耦合分析．以江 西某座已发生严重冲刷病害的桥梁为例，利用所提出的全过程仿真分析方法，明确了拱脚与桥墩接触应力是判断浅 基础双曲拱桥倒塌的关键指标，揭示了该类桥型水毁的失效模式与机理，并验证了该方法的可行性与合理性．结果 表明：拱圈拱脚与桥墩顶部界面接触失效是该类桥型水毁倒塌的根本原因；若冲刷桥墩为非制动墩，还会因不平衡 水平推力引发相邻跨拱圈及拱上建筑的连续倒塌．
Abstract_English:Hydraulic bridge failures are often extremely sudden and destructive. This type of failure is mainly caused by a local scour of the bridge foundation leading to the instability of the substructure or the failure of key components，which in turn causes the collapse of the entire bridge. Traditional analysis methods regard it as two separate processes of scour and collapse，ignoring their inherent tight coupling，which makes the objective and accurate analysis of the entire process of bridge flooding difficult. In response to this issue，this paper proposes a series of steps for the analysis of such failures. First，a structural collapse module is established through Ls-Dyna based on the finite element model of the full bridge. The contact conditions and failure criteria of each member are set，and the dynamic spring boundary conditions are applied to simulate the development of the local scour. Using Fluent to establish a dynamic mesh scour analysis module with the consideration of bed-suspended sediment loads，a method for determining the scour form at the bottom of the shallow foundation is then proposed. The scour surface of the riverbed that reflects the erosion characteristics of the bottom of the shallow foundation is obtained by fitting the boundary data of scour pit reflecting the law of scour development. Based on the calculation results of this module，the wave-flow stress of the foundation wall and the hollowing depth of the foundation bottom are extracted. Finally， Python is used to establish a scour-collapse cross-scale interface to interpolate the key physical quantities of the scour module and convert them to a module in real-time to complete the cross-scale coupling analysis of the entire process of scouring and collapse. A case study is performed on a bridge in Jiangxi province that has suffered severe scour. The proposed simulation analysis method is applied to demonstrate that the contact stress between the arch foot and pier is a key indicator in judging the collapse of a double-curved arch bridge with a shallow foundation. The failure mode and mechanism of the hydraulic bridge failure of such bridges are revealed. The feasibility and rationality of the proposed method are also verified. Results show that the contact failure between the arch foot and pier is the fundamental reason for the collapse of such bridges. If the scoured pier is a non-force-bearing pier，the unbalanced horizontal push forces can further make the adjacent arch rings，and spandrel structures progressively collapse.
Keyword_Chinese:双曲拱桥；浅基础；冲刷；水毁；倒塌；失效模式
Keywords_English:double-curved arch bridge；shallow foundation；scour；flood-induced failure；collapse；failure mode

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