竹巴龙金沙江大桥水毁破坏机理  

Failure Mechanism of Flood Damage to Jinsha River Bridge at Zhubalong

作　　者：杨万理[1] 秦军武 侯海林 吴文博 周凌远[1] YANG Wanli;QIN Junwu;HOU Hailin;WU Wenbo;ZHOU Lingyuan(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031

出　　处：《西南交通大学学报》2022年第1期120-128,共9页Journal of Southwest Jiaotong University

基　　金：国家自然科学基金(51678491);四川省科技厅重点研发计划(2019YFG0001,2019YFG0460);四川省科技计划(2021JDTD0012)。

摘　　要：为了研究竹巴龙金沙江大桥的破坏机理,基于泄洪实测数据,并考虑T梁底部横隔板腔室中裹挟空气的影响,建立了该桥1∶20缩尺数值仿真模型,对洪水作用下简支T梁桥上部结构洪水作用力特征、流场特征和破坏机理开展了深入研究.研究结果表明:当淹没率不超过1.342时,水平力系数随淹没率的增大而增大,当淹没率大于1.342时,水平力系数随淹没率的增大逐渐减小;在壅水翻越护栏前,竖向力和倾覆弯矩系数随着淹没率的增大而逐渐增大;当壅水翻越护栏后,竖向力和倾覆弯矩系数将急剧减小;在淹没率接近1.000时,上部结构发生破坏的风险最大;该桥破坏过程中首先发生了水平运动,随后大概率发生上浮和翻转,梁体运动导致挡块破坏,部分梁体在跌落中发生翻转;实心栏杆贡献了多达31%的水平力,裹挟空气对竖向力的贡献最高达到18%,实心栏杆和裹挟空气是引起该桥水毁破坏或加速该桥破坏的重要原因.To explore the failure mechanism of Jinsha River Bridge at Zhubalong,a 1∶20 scaled numerical simulation model of the bridge was built with the measured field data in flood discharge,while the influence of air trapped in the diaphragm chamber at the bottom of T-beam is analyzed.The characteristics of flood force,flow field and failure mechanism of superstructure of the simply supported T-beam bridge under the effect of flood are studied in depth.Results show that when the submergence ratio is less than 1.342,the horizontal force coefficient increase with the ratio;when it is beyond 1.342,the coefficient decreases with the ratio.Before the backwater crosses the guardrail,the vertical force and overturning moment coefficient gradually increase with the submergence ratio.When it crosses the guardrail,the vertical force and overturning moment coefficient decrease sharply.When the submergence ratio is close to 1.000,the risk of the superstructure failure is the greatest.During the failure process of the bridge,horizontal movements occur first,and then there is a high probability that floating and overturning occur.The beam movement leads to the destruction of the link stopper,and part of the beam overturns in the falling.Solid railings contribute up to 31%of the horizontal force,and the contribution of entrapped air to the vertical force is up to 18%.Solid railings and entrapped air are important causes for flood damage or accelerating the bridge damage.

关 键 词：洪水 梁桥 破坏机理 裹挟空气 

分 类 号：U447[建筑科学—桥梁与隧道工程]