整体式斜交桥台-桩-土体系往复加载拟静力试验  

Pseudo-static Cyclic Test on Skewed Integral Abutment-pile-soil System

作　　者：赵秋红[1,2] 翁琴龙 黄福云[3] 陈宝春[3] ZHAO Qiu-hong;WENG Qin-long;HUANG Fu-yun;CHEN Bao-chun(School of Civil Engineering,Tianjin University,Tianjin 300350,China;Key Laboratory of Coast Civil Structure Safety of Ministry of Education,Tianjin University,Tianjin 300350,China;School of Civil Engineering,Fuzhou University,Fuzhou 350108,Fujian,China)

机构地区：[1]天津大学建筑工程学院,天津300350 [2]天津大学滨海土木工程结构与安全教育部重点实验室,天津300350 [3]福州大学土木工程学院,福建福州350108

出　　处：《中国公路学报》2022年第11期73-85,共13页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(51878447,51678406)。

摘　　要：将整体式桥台引入斜交桥中形成整体式斜交桥,可有效改善地震中桥梁上部结构纵横向耦连效应造成的面内扭转及落梁现象;但整体式桥台中主梁与桥台浇筑为一体,在地震作用下将发生复杂的桥台-桩-土相互作用。为此,以某整体式斜交桥为原型,开展了斜交桥台-H形钢桩-土体系往复加载拟静力试验研究,探究了体系的抗震性能、台后土压力分布规律以及桥台和钢桩的水平变形特征等。结果表明:斜交桥台-H形钢桩-土体系具有较高的耗能能力及延性,台后土对体系的抗震性能影响显著。台后土提高了体系抗侧承载力及刚度,但亦造成正负向受力不对称性,其中正向抗侧承载力及刚度明显高于负向,但残余承载力及位移明显小于负向。在小位移(<0.01H,H为桥台高度)下,斜交桥台的台后土压力沿埋深方向近似呈三角形分布,最大土压力位于台底;沿水平方向呈抛物线形分布,最大土压力位于距桥台锐角0.25 m处;沿纵桥向呈三角形分布,最大土压力位于台背。在大位移(≥0.01H)下,台后土靠台背处出现明显扇形塌陷区域,导致桥台顶部土压力降低,沿埋深方向开始呈双折线分布,沿水平方向呈三折线分布,最大土压力位置不变;沿纵桥向呈双折线分布,最大土压力与台背距离随加载位移逐渐增加。试验结束时,桥台顶部塌陷区域深度近500 mm,宽度近600 mm。加载过程中桥台基本为刚体,出现平动及转动位移;由于部分台后土流动至钢桩前侧,钢桩顶部产生朝向台后土方向的局部累积变形,桩身水平变形在埋深0.25 m处出现拐点及最大值,而非桩顶,试验结束后无明显残余变形。Introducing an integral abutment into a skewed bridge to form a skewed-integral-abutment bridge(SIAB) can improve the in-plane torsion and the beam drop phenomenon of a superstructure during an earthquake. Owing to the integration of the girder and abutment, complicated abutment-pile-soil interactions occur when the SIAB suffers from seismic load. A pseudo-static cyclic test on the behavior of a skewed-integral-abutment-steel-H-pile-soil system was conducted based on an existing integral-abutment bridge. The seismic performance of the skewed-integral-abutment-steel-H-pile-soil system, the distribution of backfill pressure, and the horizontal deformation of the steel H-pile were studied. The test results indicate that the skewed-integral-abutment-steel-H-pile-soil system has an excellent energy dissipation capacity and ductility. The backfill has a significant effect on the seismic performance of the system. Backfill increases the lateral bearing capacity and stiffness;however, it makes the residual force and displacement asymmetrical when loading in the positive and negative directions. During positive loading, the lateral bearing capacity and stiffness are higher, however the residual bearing capacity and residual displacement are lower. When the displacement is small(<0.01H, where H is the abutment height), the earth pressure distribution behind the skewed abutment is triangular along the vertical direction with the maximum at the bottom of the abutment, parabolic along the horizontal direction with the maximum at 0.25 m from the abutment acute corner, and triangular along the longitudinal direction with the maximum at the back of the abutment. When the displacement is large(≥0.01H), an obvious fan-shaped settlement occurs at the top of the backfill, and the earth pressure drops in the area. The earth pressure presents a twofold linear distribution along the vertical direction and a threefold linear distribution along the horizontal direction, with the position of the maximum earth pressure remains unchanged.

关 键 词：桥梁工程 桥台-桩-土相互作用 往复加载拟静力试验 H形钢桩 整体式斜交桥 台后土压力 

分 类 号：U443.22[建筑科学—桥梁与隧道工程]