整体桥预应力桩-土相互作用试验  

Experiment on Interaction of Prestressed Pile-soil in Integral Bridge

作　　者：黄福云[1,2] 何凌峰 单玉麟 王静杰 张峰[1,2] HUANG Fu-yun;HE Ling-feng;SHAN Yu-lin;WANG Jing-jie;ZHANG Feng(College of Civil Engineering,Fuzhou University,Fuzhou 350108,Fujian,China;Fujian Provincial Key Laboratory on Multi-disasters Prevention and Mitigation in Civil Engineering,Fuzhou University,Fuzhou 350108,Fujian,China)

机构地区：[1]福州大学土木工程学院,福建福州350108 [2]福州大学福建省土木工程多灾害防治重点实验室,福建福州350108

出　　处：《建筑科学与工程学报》2021年第1期31-40,共10页Journal of Architecture and Civil Engineering

基　　金：国家自然科学基金项目(51578161);福州市科技计划项目(2018-G-63)。

摘　　要：为探究整体式桥台无缝桥(简称整体桥)预应力混凝土桩吸纳上部结构变形的能力,对3根不同预应力的缩尺模型桩PC-1~PC-3进行了拟静力试验。利用布设于桩身表面的土压力计、位移计、应变片等,研究了预应力混凝土桩的破坏模式和变形规律,并与埋深不同且未施加预应力的混凝土桩对比,进一步说明预应力对柔性桩变形能力的影响;通过与普通混凝土桩的对比,以临界荷载、屈服荷载、峰值荷载为评价指标,分析了预应力对试验桩强度和变形的影响。结果表明:随着预应力度的增大,模型桩的破坏形态由多条裂缝向1条主要裂缝转变;PC-2和PC-3主要裂缝出现位置分别较PC-1沿埋深方向增大0.4倍和0.6倍桩径,说明预应力度的提高增大了桩-土相互作用区域,且效果较增大桩基埋深更为显著;随着位移荷载的增加,PC-1的桩身拉、压应变分布率先出现不对称,而PC-2和PC-3在更大位移荷载时仍保持对称,通过与不同埋深未施加预应力的混凝土桩对比发现,相较于增大桩基埋深,施加预应力可以更为显著地提高桩基的弹性工作范围及桩身的整体性和抗开裂能力;通过分析比较模型桩的桩身承载比可知,提高预应力度可改善桩身受力性能,并可更充分发挥桩周土的承载能力;PC-2,PC-3的正向临界荷载、屈服荷载以及峰值荷载相较于PC-1均有提高,屈服荷载分别较PC-1提高了17.8%和42.3%,说明预应力度可以增大混凝土桩的弹性工作范围,提高变形能力;PC-1的等效刚度退化速率较PC-2,PC-3更快,说明施加预应力可减缓混凝土桩的刚度退化;与PHC管桩等效刚度理论计算值对比发现,PHC管桩理论计算值偏安全,可应用于PC桩的等效刚度计算。In order to explore the ability of prestressed concrete piles to absorb the deformation of superstructure of integral abutment jointless bridge(IAJB),the quasi-static tests of three scaled model piles PC-1 to PC-3 with different prestress levels were carried out.The failure mode and deformation law of prestressed concrete pile were studied by means of earth pressure gauge,displacement gauge and strain gauge.Compared with the concrete piles with different buried depths and without prestress,the influence of prestress on the deformation capacity of flexible piles was further explained.Compared with ordinary concrete pile,the influence of prestress on the strength and deformation of test pile was analyzed with critical load,yield load and peak load as evaluation indexes.The results show that with the increase of prestress level,the failure mode of model pile changes from multiple cracks to one main crack.The location of main cracks in PC-2 and PC-3 is 0.4 and 0.6 times larger than that of PC-1 along the buried depth direction,which indicates that the increase of prestress level increases the pile-soil interaction area,and the effect is more significant than that of increasing the buried depth of pile foundation.With the increase of displacement load,the tensile and compressive strain distribution of PC-1 first appears asymmetry,while PC-2 and PC-3 remain symmetrical under larger displacement load.Compared with the non prestressed concrete piles with different buried depths,it is found that the application of prestress can significantly improve the elastic working range of pile foundation and the integrity and anti cracking ability of pile body compared with increasing the buried depth of pile foundation.Through the analysis and comparison of the bearing ratio of the model pile,it can be seen that increasing the prestress can improve the bearing capacity of the pile body and give full play to the bearing capacity of the soil around the pile.Compared with PC-1,the positive critical load,yield load and peak load of PC-

关 键 词：桥梁工程 预应力桩 拟静力试验 整体式桥台无缝桥 桩-土相互作用 变形能力 

分 类 号：TU473[建筑科学—结构工程]