黄土地区桩端后注浆群桩基础承载特性分析  

Analysis on Bearing Characteristics of Pile Groups with Post-Grouting at Pile Ends in Loess Areas

作　　者：周志军[1] 田叶青 张铭驿 王康超 朱珊珊 ZHOU Zhijun;TIAN Yeqing;ZHANG Mingyi;WANG Kangchao;ZHU Shanshan(School of Highway,Chang’an University,Xi’an 710064,China;Yunnan Academy of Transportation Sciences Co.,Ltd.,Kunming 650011,China;Shandong Construction Engineering Quality Inspection Center Co.,Ltd.,Jinan 250031,China)

机构地区：[1]长安大学公路学院,西安710064 [2]云南省交通科学研究院有限公司,昆明650011 [3]山东省建筑工程质量检验检测中心有限公司,济南250031

出　　处：《工业建筑》2024年第3期182-190,共9页Industrial Construction

摘　　要：通过研究现场两根钻孔灌注单桩注浆前、后承载特性的变化,运用Vesic理论推导得到现场试验条件下桩端压密注浆后水泥浆液的塑性影响区半径。利用ABAQUS软件建立单桩模型以及考虑桩数、桩距、注浆情况的2×2(桩间距变化范围为2~6倍桩径),3×3(桩间距为3倍桩径)的群桩模型,研究桩端注浆对桩基沉降量、桩端阻力、桩侧阻力、端阻比的影响。结果表明:桩间距相同时,随桩数的增多,群桩基础注浆承载力发挥效率减弱;不同桩间距的2×2群桩基础注浆后承载力由大到小的桩距排序为:5、6、4、3倍桩径;桩间距为5倍桩径时,桩端扩大头的黏结作用和群桩效应得到了最大程度的发挥;同一工况下,注浆后端阻比显著提高,桩数相同时,端阻比随桩间距的增大而逐渐减小;桩间距较小时,桩端阻力相较于桩侧摩阻力提高更明显。由于边桩、角桩和桩周土体形成的整体在桩基沉降过程中对中桩的夹持作用,角桩和边桩的桩侧摩阻力先于中桩发挥,桩侧摩阻力由大到小排序为:角桩、边桩、中桩。By studying the variations of bearing capacity characteristics of two bored piles before and after being grouted,the radius of the plastic influential zone of cement pastes after being compactedly grouted at pile ends was derived by Vesic’s theory.A single pile model and pile group models considering different quantities of piles,pile spacing,and grouting conditions were respectively constructed,in which the pile spacing was 2 to 6-times pile diameters for 2×2 pile groups and 3-times pile diameters for 3×3 pile groups.Then,the effect of grouting at pile ends on settlement,pile end resistance,pile side resistance,and ratios of pile end resistance and total resistance were studied.The conclusions were that the grouting bearing capacity efficiency for pile group foundations dropped with an increase in pile quantities in the same pile space.The order of the bearing capacity of 2×2 pile group foundations from large to small was the foundation with pile space of 5-,6-,4-,and 3-times pile diameters.When the pile spacing was 5-times pile diameters,the bonding effect of expanding heads of pile ends and pile group effect were maximized.In the same working condition,the ratio of end resistance and total resistance was significantly enhanced after being grouted,while in the same quantity of piles,the ratio of end resistance and total resistance dropped gradually with an increase in pile space.When the pile space was smaller,the end resistance of piles increased more apparently than the side friction resistance of piles.As the ferrule effect by side piles,corner piles and surrounding soil on middle piles in settlement processes of pile foundations,lateral friction resistance of corner piles and side piles worked earlier than that of middle piles.The order of lateral friction resistance from large to small was that of corner piles,side piles and middle piles.

关 键 词：桩基 桩端后注浆 群桩基础 数值模拟 桩侧阻力 桩端阻力 

分 类 号：TU473.1[建筑科学—结构工程]