摘要
由于整体式桥台无缝桥(以下简称整体桥)具有诸多优点,因而在欧美等国得到广泛应用。不过,整体桥结构的特殊性会引起复杂的结构-土相互作用。为了适应整体桥上部结构的纵向变形,国外多采用H型钢桩,而我国以混凝土桩(RC桩)为主。大量研究及工程实例表明,采用RC桩能够满足整体桥变形要求,但台后土对RC桩内力的影响尚不明确。为此,选取国内某整体桥为背景,以RC桩的配筋率及截面形状为设计参数制作了4个整体式桥台-RC桩试验模型,对其开展整体式桥台-RC桩-土相互作用低周往复荷载拟静力试验研究,主要研究了整体式桥台-RC桩-土体系的破坏形态、滞回耗能性能、水平变形规律和相互作用机制等。试验研究表明,往复位移加载下台后填土会出现脱空现象,试件破坏位置主要集中于桥台底部与桩顶连接头处及其下部一定埋深范围内,增大RC桩配筋率或采用矩形截面RC桩可使破坏位置下移,改善其受力性能。整体式桥台-RC桩-土体系的滞回曲线在第一象限较为饱满,表现出较好的耗能能力,而第三象限滞回曲线包裹面积较小。增大RC桩的配筋率或采用矩形截面RC桩可增大整体式桥台-RC桩-土体系的耗能能力与承载力,并可增大RC桩的弹性开裂位移,使其更晚屈服和破坏,同时其刚度退化速率和退化幅度也可显著减小。试验研究还表明,当加载位移超过弹性极限位移时,整体桥混凝土桩基的水平变形会出现明显的累积现象。同时,桥台与桩身连接头的相对转角随着损坏程度的增加而增大。提高RC桩配筋率或采用矩形截面RC桩后,桥台与桩身连接头的破坏明显减轻,累积变形显著减小。
The integral abutment jointless bridge(IAJB)has lots of advantages,so it has been widely used in western countries.The pile foundation of IAJB requires higher horizontal deformation capacity.H-beam steel piles are often used to construct integral bridges in the west,while RC piles are mainly adopted in China.Lots of studies and engineering examples show that the application of RC piles can meet the deformation requirements of IAJBs,but the influence of the earth pressure behind abutment on RC piles is not clear.Therefore,based on a practical IAJB in China as an engineering background,with certain RC pile reinforcement ratio and the shape of the section as parameter,four integral abutment-RC pile test models were designed.The reciprocating low-cycle pseudo-static test on interaction of integral abutment-H-shaped pile-soil was carried out to study the hysteretic behavior,lateral deformation law and interactive mechanism.The test results show that under the reciprocating displacement loading,the soil behind the abutment will be emptied,and the failure positions of the specimens are mainly concentrated at the connection between the bottom of the abutment and the top of the pile.Increasing the reinforcement ratio of RC piles or using rectangular section RC piles can lower the failure positions and improve their mechanical properties.The hysteretic curve of the integral abutment-RC pile-soil system is full in the first quadrant,indicating better energy dissipation capacity,while the third quadrant hysteretic curve has a smaller covering area.The experimental results also show that the abutment movement can be regarded as a rigid displacement with rotation,and under the action of reciprocating displacement beyond the limit of elastic deformation,the abutment and the pile appear obvious cumulative deformation.Besides,the relative angle between abutment and pile head increases as the damage degree increases.Accordingly,by increasing the reinforcement ratio of RC piles or adopting rectangular section RC piles,1)the energy dissipation capacity of the whole bridge-RC pile-soil system can be increased;2)the elastic cracking displacement of RC piles can also be increased,which leads to its later yield and failure and increases the bearing capacity of the whole system;3)the stiffness degradation rate and degradation amplitude of the system are significantly reduced;4)the failure of bridge abutment and pile joint,along with the accumulated deformation,can be effectively reduced.
作者
黄福云
何凌峰
单玉麟
胡晨曦
周志明
HUANG Fu-yun;HE Ling-feng;SHAN Yu-lin;HU Chen-xi;ZHOU Zhi-ming(College of Civil Engineering,Fuzhou University,Fuzhou,Fujian 350108,China;Fujian Key Laboratory of Engineering Structure,Fuzhou University,Fuzhou,Fujian 350108,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2021年第7期1803-1814,共12页
Rock and Soil Mechanics
基金
国家自然科学基金项目(No.51578161)
福建省新世纪优秀人才计划(No.50011504)。
关键词
桥梁工程
拟静力试验
桥台-桩-土相互作用
RC桩
配筋率
截面形状
变形性能
bridge engineering
pseudo-static test
interaction of abutment-pile-soil
RC pile
ratio of reinforcement
shape of pile section
deformation capacity
作者简介
第一作者:黄福云,男,1979年生,博士,教授,主要从事结构抗震和基础工程领域的研究。E-mail:Huangftiyun@fzu.edu.cn。
