深厚卵石层后压浆灌注桩承载性能研究  

Research on Load Bearing Performance of Post-Grouting Bored Piles in Deep and Thick Pebble Layer

作　　者：周霄 王铖铖[2] 刘新华[2] 徐欣[2] ZHOU Xiao;WANG Cheng-cheng;LIU Xin-hua;XU Xin(Hubei Provincial Communications Investment Industrial Development Co.,Ltd.,Wuhan 430056,China;CCCC Second Highway Consultants Co.,Ltd.,Wuhan 430056,China)

机构地区：[1]湖北交投实业发展有限公司,湖北武汉430056 [2]中交第二公路勘察设计研究院有限公司,湖北武汉430056

出　　处：《桥梁建设》2023年第S01期31-37,共7页Bridge Construction

基　　金：贵州省交通运输厅科技项目(2022-122-021)。

摘　　要：为研究深厚卵石层后压浆灌注桩的承载性能,以湖北观音寺长江大桥为背景,通过现场自平衡静载试验进行后压浆灌注桩承载性能研究。采用分布式后压浆技术,通过试桩现场试验获取压浆前、后深厚卵石层桩土接触界面桩侧摩阻力τ~桩土相对位移s、桩端阻力q u~桩端位移s u关系曲线,揭示后压浆对桩土接触界面剪切力学特性的影响,通过压浆前、后的桩侧、桩端初始刚度变化揭示压浆效应对深厚卵石层桩基承载能力增强的作用机理。结果表明:卵石层灌注桩采用分布式后压浆可以有效提高桩基的极限承载力,减小桩顶沉降;压浆后灌注桩桩侧摩阻力、桩端承载力得到提高,桩侧、桩端初始刚度得到增强,承载性能明显改善;现场实测桩基各承载性能指标约为理论值的1.1倍;压浆后桩基各承载性能指标为压浆前的1.8~2.0倍。In this paper,the Guanyinsi Changjiang River Bridge in Hubei Province is used as a case,combined with field self-balancing static load test,to study the load bearing performance of post-grouting bored piles in deep and thick pebble layer.Trial piles were prepared and post grouted for the test,based on which the variation of a series of parameters before and after grouting was investigated,and the relationship between lateral pile surface frictionτand pile-soil relative displacement s as well as the relationship between pile-tip resistance q u and pile-tip displacement s u concerning the pile-soil interface in the deep and thick pebble layer were fitted,to reveal the influence of post grouting on the shear property of pile-soil interface.The variation of the pile-shaft and pile-tip initial stiffness before and after grouting was analyzed to figure out the strengthening effect of grouting on the load bearing performance of bored piles in deep and thick pebble layer.The results demonstrate that the distributed post-grouting can effectively improve the ultimate load bearing capacity of bored piles in deep and thick pebble layer and reduce pile-top settlement.After grouting,the pile surface friction and pile-tip load bearing capacity are enhanced,the pile-shaft and pile-tip initial stiffness has got strengthened and the load bearing capacity of the pile is remarkably improved.The measured indicators of load bearing capacity are 1.1 times of the theoretical values.After grouting,the indicators of load bearing capacity are 1.8 to 2.0 times of the values before grouting.

关 键 词：桥梁工程 钻孔灌注桩 深厚卵石层 分布式后压浆 承载性能 初始刚度 自平衡静载试验 

分 类 号：U443.154[建筑科学—桥梁与隧道工程]