埋入式后压浆管桩竖向抗拔破坏模式研究  

Uplift failure of drilled and post-grouted concrete pile

作　　者：邹志炎 卢继忠 张逸博 傅旭东[1] ZOU Zhiyan;LU Jizhong;ZHANG Yibo;FU Xudong(School of Civil Engineering,Wuhan University,Wuhan 430072,China)

机构地区：[1]武汉大学土木建筑工程学院,湖北武汉430072

出　　处：《铁道科学与工程学报》2024年第2期602-612,共11页Journal of Railway Science and Engineering

基　　金：国家自然科学基金面上资助项目(51978540)。

摘　　要：埋入式后压浆管桩作为一种新型桩基础,集钻孔灌注桩和预应力管桩的优点于一体,可以解决灌注桩桩身质量不可靠和预应力管桩沉桩困难等问题。对埋入式后压浆管桩的竖向抗拔试验进行CT扫描,得到不同位移状态下模型桩的CT扫描图像,直观地揭示破坏面的发展规律,并建立破坏面方程。对其他学者提出的抗拔桩破坏面方程进行优化,通过静力平衡方程,获得优化后破坏面方程对应的埋入式后压浆管桩抗拔极限承载力函数,并采用遗传算法确定优化后破坏面方程的参数。将多种理论假定破坏面与试验获得的破坏面进行对比分析,验证所得破坏面方程的准确性。研究发现:埋入式后压浆管桩在上拔位移到达0.45倍桩径时发生破坏,此时灌浆层与土体紧密结合,两者之间未出现明显位移,破坏仅发生在灌浆层之外的桩周土体中;破坏面从桩底向桩顶延伸,越靠近桩顶,破坏面距离桩身越远,破坏面在桩底与混凝土侧壁相切,在地面与水平面的夹角接近42°,呈喇叭形破坏;本文的理论假定破坏面与试验获得的破坏面的相关指数R^(2)=0.97,前人的理论假定破坏面与试验获得的破坏面的相关指数R^(2)=0.91,本文的破坏面方程更加贴近试验获得的破坏面。研究成果对埋入式后压浆管桩的设计计算具有重要的参考价值。The drilled and post-grouted concrete pile,combining the advantages of bored piles and prestressed pipe piles,presents a novel foundation solution.It can solve the problems such as unreliable quality of pile body of grouted pile and difficulty in sinking prestressed pipe pile.CT scans were performed for the uplift test of buried post-pressure pipe piles.CT scan images of model piles under different displacement states were obtained to visually reveal the damage surface development and to establish the damage surface equation.The damage surface equation of the pullout resistant pile proposed by other scholars was optimized,the uplift limit bearing capacity function of drilled and post-grouted concrete pile corresponding to the damage surface was optimized through the static equilibrium equation,and the parameters of the optimized damage surface equation were determined by using genetic algorithm.The accuracy advantage of the resulting damage surface equation was verified by comparing multiple theoretical assumed damage surface with the experimentally obtained damage surface.The findings are as follows:the damage of drilled and post-grouted concrete pile occurs when the uplift displacement reaches 4.5 mm;and when the grout layer and the soil are tightly bonded and no obvious displacement occurs between the two,the damage only occurs in the soil around the pile outside the grout layer.The damage surface extends from the bottom of the pile to the top of the pile,i.e.,the closer to the top of the pile,the farther the damage surface is from the pile body.The damage surface is tangential to the concrete sidewall at the bottom of the pile,and the angle between the ground and the horizontal plane is close to 42°with a flared damage.The theory in this paper assumed that the correlation coefficient of R^(2)=0.97 between the damage surface and the experimentally obtained damage surface,whereas the previous theory assumed the correlation coefficient of R^(2)=0.91 between the damage surface and the experimentally obtained dam

关 键 词：铁路电力工程 埋入式后压浆管桩 CT扫描 破坏面 抗拔极限承载力 遗传算法 

分 类 号：TU473.1[建筑科学—结构工程]