基于水流冲击响应的桥墩冲刷识别方法研究  

Research on Scour Identification Method of Bridge Pier Based on Impact Response of Water Flow

作　　者：陈旭辉 唐永圣 梅曦 沈国根 CHEN Xuhui;TANG Yongsheng;MEI Xi;SHEN Guogen(College of Civil and Transportation Engineering,Hohai University,Nanjing 210098,China;Jiangsu Huatong Engineering Checking&Measuring Co.Ltd.,Nanjing 210014,China;Yangzhou Tunnel Management Office,Yangzhou 225100,Jiangsu China)

机构地区：[1]河海大学土木与交通学院,南京210098 [2]江苏华通工程检测有限公司,南京210014 [3]扬州市隧道管理处,江苏扬州225100

出　　处：《河南科学》2022年第9期1441-1448,共8页Henan Science

基　　金：国家重点研发计划(2021YFB2601200);中央高校基本科研业务费专项资金资助项目(B210202044);扬州市建设科技计划项目(202104)。

摘　　要：在跨江、跨河桥梁中,桥墩的安全往往受到水流的影响.由于洪水冲刷导致桥墩自由段长度增加,降低了桥墩的稳定性,严重时可能造成桥梁失稳倒塌,因此对桥墩冲刷进行监测具有重要意义.然而,在洪水暴发期间,现有测量技术难以精准实施桥墩冲刷监测.为此提出一种基于水流冲击响应的桥墩冲刷识别方法,首先,建立桥墩简化模型及其振动方程,推导桥墩自由段长度与固有频率的关系;然后,基于桥墩在地基中的等效嵌固理论建立桥墩自由段长度的修正方法,进而提出桥墩自由长度计算方法;最后,基于ABAQUS有限元软件建立桥梁有限元模型,考察该方法在不同冲刷情况下的识别精度.结果发现,桥墩自由长度识别误差在6%以内,并且在不同波浪荷载作用下该方法均具有稳定性.通过现场实桥试验对本文方法进行验证,并比较了人工锤击和水流冲击两种激励方法的异同点.结果表明,两种激励方法所得结果相近,桥墩自由长度识别误差可控制在10%左右,且传感器便于安装、成本低、识别精度高,因此该方法具有较好的应用前景.In cross-river bridges,the safety of piers is often affected by water flow. Due to flood scour,the length of the free section of the bridge pier increases,which reduces the stability of the bridge pier,and may cause bridge collapse in severe cases. Therefore,it is of great significance to monitor the bridge pier scour. However,existing measurement techniques are insufficient in bridge pier scour monitoring,especially during flooding outbreak. Therefore,a method for scour identification of bridge pier based on impact response of water flow is proposed. First,a simplified model of the bridge pier is introduced and its vibration equation is established. The relationship between the length of the free section of the bridge pier and the natural frequency is deduced. Second,based on the equivalent embedding theory of the bridge pier in foundation,a correction method for the length of the free section of the bridge pier is established,and then the calculation method of the free section length of bridge pier is proposed. Finally,the finite element model of the bridge is established based on the ABAQUS finite element software,and the identification accuracies of the method under different scour conditions are investigated. The results show that the identification error of the free section length of the bridge pier is within 6%,and the method is stable under different wave loads. The proposed method is verified by real bridge tests,and the similarities and differences between the two excitation methods of artificial hammering and water flow impact are compared. The results obtained by the two excitation methods are similar,and the identification error of the free section length of the bridge pier can be controlled at about 10%. This method has a good application prospect besause it has the advantages of easy installation of the sensor,low cost and high identification accuracy.

关 键 词：桥墩冲刷 水流冲击响应 固有频率 等效嵌固深度 桥墩长度识别 

分 类 号：U446.3[建筑科学—桥梁与隧道工程]