考虑冲刷效应的钢筋混凝土拱桥桩基地震易损性分析  

Seismic fragility analysis of pile foundation of reinforced concrete arch bridge considering scouring effect

作　　者：雷体生 杨华平 钱永久[3] Lei Ti-sheng;Yang Hua-ping;Qian Yong-jiu(Chengdu Branch of CCDI(Suzhou)Exploration&Design Consultant Co.Ltd,Chengdu 610051,China;School of Architecture and Civil Engineering,Chengdu University,Chengdu 610106,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]悉地(苏州)勘察设计顾问有限公司成都分公司,四川成都610051 [2]成都大学建筑与土木工程学院,四川成都610106 [3]西南交通大学土木工程学院,四川成都610031

出　　处：《工程抗震与加固改造》2023年第1期150-157,共8页Earthquake Resistant Engineering and Retrofitting

摘　　要：冲刷将侵蚀桥梁桩基周围的土体,致其侧向约束减弱,影响桥梁结构的受力行为,这对于拱桥结构而言更甚。鉴于此,以某三跨连拱坦拱桥为例,依托SAP2000软件建立全桥有限元模型,通过m法模拟桩土相互作用,采用曲率延性作为桩基的损伤指标,基于增量动力分析方法,计算出不同地震等级下的曲率响应峰值,进而给出不同冲刷深度时,主拱桩基对应轻微损伤、中等损伤、严重损伤和完全破坏状态的地震易损性曲线。研究表明:在一定冲刷深度范围内,拱桥桩基的损伤概率随冲刷深度增加而加剧;当冲刷深度超过一定值后,桩基的地震损伤概率明显减小。同时,拱桥桩基冲刷深度达到3m后,恒载作用下,主拱承台的顺桥向变形略微增大,其在地震下的位移响应也随PGA增加而非线性增大。可见,桩基础冲刷至一定深度时,静/动力荷载均可能影响桥梁结构的安全性。因此,拱桥桩基需合理考虑桩基防冲刷措施,且抗震设计时需考虑冲刷深度对拱桥桩基地震易损性的影响。Scouring will erode the soil around the bridge pile foundation,which could reduce the lateral restraint of the foundation and affect the mechanical behavior of the bridge structure,this is even more true for arch bridge structures.Based on an engineering example of a flat arch three-span multi-arch arch bridge,the finite element model of the bridge is established by using SAP2000.The pile-soil interaction is considered through m method.The curvature ductility is selected as the damage index of the pile foundation.Based on the incremental dynamic time history analysis,the peak curvature response of pile foundation under different seismic intensity is obtained.Furthermore,the seismic vulnerability curves of the main arch pile foundation corresponding to minor damage,moderate damage,severe damage,and entire damage states under different scour depths are given.Research shows that:in a certain range of scour depth,the damage probability of arch bridge pile foundation increases with the increase of scour depth.When the depth exceeds a certain value,the seismic damage probability of the pile foundation decreases obviously.Moreover,the deformation along the bridge direction of the main arch rib cap under the dead load increases slightly when the scour depth is 3m,and the displacement response under the earthquake increases nonlinearly with the increase of PGA as well.Accordingly,the static and dynamic actions will affect the safety When the pile foundation is washed to a certain depth.Therefore,it is necessary to reasonably consider the anti-scouring measures of pile foundation for this kind of arch bridge.The influence of scouring depth on seismic vulnerability of arch bridge pile should be considered in seismic design.

关 键 词：冲刷效应 钢筋混凝土拱桥 桩基 地震易损性分析 有限元模型 

分 类 号：U442.55[建筑科学—桥梁与隧道工程]