分布式后压浆超长大直径灌注桩竖向承载性能试验研究  

Experimental study on axial bearing behavior of super-long and large-diameter bored pile with distributed post-grouting

作　　者：王卫国 万志辉[1,2,3] 戴国亮 钱晓楠[1] 胡涛 周峰[2] 张鹏 WANG Weiguo;WAN Zhihui;DAI Guoliang;QIAN Xiaonan;HU Tao;ZHOU Feng;ZHANG Peng(School of Civil Engineering,Southeast University,Nanjing 211189,China;School of Transportation Engineering,Nanjing Tech University,Nanjing 211816,China;China Construction Industrial&Energy Engineering Group Co.,Ltd,Nanjing 210023,China)

机构地区：[1]东南大学土木工程学院,江苏南京211189 [2]南京工业大学交通运输工程学院,江苏南京211816 [3]中建安装集团有限公司,江苏南京210023

出　　处：《建筑结构学报》2024年第4期155-165,共11页Journal of Building Structures

基　　金：国家自然科学基金项目(52008100);江苏省自然科学基金项目(BK20200400);中国博士后科学基金面上项目(2022M723534);江苏省碳达峰碳中和科技创新专项(BE2022605)。

摘　　要：基于山东小清河复航工程开展2根超长大直径灌注桩压浆前后现场静载试验,对比分析组合式后压浆桩与分布式后压浆桩压浆前后的承载性状,研究分布式后压浆对超长大直径灌注桩承载变形、荷载传递特性以及桩侧摩阻力与桩端阻力的影响。结果表明:相比压浆前,组合式后压浆桩与分布式后压浆桩的承载力提高幅度分别为39.6%、52.2%,分布式后压浆桩的承载性能较组合式后压浆桩的更优,其改善桩基荷载传递特性更为明显;在极限状态下,组合式后压浆桩与分布式后压浆桩的侧摩阻力与端阻力均得到了显著提高,有效地改善了桩侧与土体的边界条件和桩端承载条件,提高了桩侧与桩端土体的强度与刚度;在相同条件下分布式后压浆桩的侧摩阻力增强系数较组合式后压浆桩的略大,且侧摩阻力增强系数随埋深的增加整体上呈现增大趋势,侧摩阻力增强系数存在深度效应。此外,通过透明土可视化模型试验进一步证实,分布式后压浆具有小间距、多断面、高密次以及多深度压浆等特点,使其注入的水泥浆液沿桩身分布更均匀,从而形成了更为紧密且稳定的桩-水泥土-土体系,对改善桩基承载特性的效果更为显著。In-situ static load tests on two super-long and large-diameter bored piles before and after grouting were conducted on the basis of the Xiaoqing River re-navigation project in Shandong Province.The influences of the distributed post-grouting on the bearing deformation behavior,load transfer characteristics,side resistance and tip resistance of the super-long and large-diameter bored piles were studied by comparing and analyzing the bearing behaviors of the combined post-grouted and distributed post-grouted piles.The results show that compared with the case before grouting,the bearing capacity of the combined post-grouted pile and the distributed post-grouted pile increases by 39.6%and 52.2%,respectively,which shows that the bearing behavior of the distributed post-grouted pile is better than that of the combined post-grouted pile.Distributed post-grouted pile also significantly improves the load transfer characteristics of pile foundation.Under the ultimate load,the side and tip resistances of the combined grouted pile and the distributed grouted pile are significantly improved,which effectively improves the boundary conditions between the pile side and soil and the load bearing conditions of the pile end,and improves the strength and stiffness of the soil at the pile side and end.Moreover,the improvement coefficients of the ultimate side resistance for the distributed post-grouted pile are slightly larger than that of the combined post-grouted pile under the same conditions,and the improvement coefficient of the ultimate side resistance increases with the increase of the buried depth,and the improvement coefficients of the ultimate side resistance has a depth effect.In addition,the transparent soil visualization model test further confirms that the cement grout injected into the distributed post-grouted pile covers the surface more evenly along the pile shaft due to its small spacing,multi-section,high density and multi-depth grouting,forming a more compact and stable pile-grout-soil interaction system,and thus

关 键 词：钻孔灌注桩 分布式后压浆 组合式后压浆 现场足尺试验 桩侧摩阻力 桩端阻力 

分 类 号：TU473[建筑科学—结构工程]