后顶扩臂压浆桩竖向承载机理及其桩盘力学性能研究  

Study on vertical bearing mechanism of post expanded arm grouting pile and mechanical property of pile plate

作　　者：朱文波[1,2] 戴国亮[1,2] 邓会元[3] 竺明星 龚维明 Zhu Wenbo;Dai Guoliang;Deng Huiyuan;Zhu Mingxing;Gong Weiming(Key Laboratory of Concrete and Prestressed Concrete Structure of Ministry of Education,Southeast University,Nanjing 211189,China;School of Civil Engineering,Southeast University,Nanjing 211189,China;CCCC Highway Consultants Co.,Ltd.,Beijing 100010,China;Jiangsu University of Science and Technology,Zhenjiang 212003,China)

机构地区：[1]东南大学混凝土及预应力混凝土结构教育重点实验室,江苏南京211189 [2]东南大学土木工程学院,江苏南京211189 [3]中交公路规划设计院有限公司,北京100010 [4]江苏科技大学,江苏镇江212003

出　　处：《土木工程学报》2024年第10期82-94,共13页China Civil Engineering Journal

基　　金：国家自然科学基金(52208333,51878160,52378328);中国交建集团揭榜挂帅项目(2023-ZJKJ-01)。

摘　　要：为了有效提高桩基础承载力,创新性提出后顶扩臂压浆技术与后顶扩臂压浆桩基础形式。其桩臂顶扩压浆后形成的桩盘力学以及承载特性直接影响基础承载力。为此,在砂土中开展后顶扩臂压浆桩模型试验以及桩盘力学性能试验,通过分析荷载位移变化规律、荷载分担比、桩盘破坏模式等,探究后顶扩臂压浆桩竖向承载特性以及桩盘的力学性能,揭示桩盘承载机理以及后顶扩臂压浆桩承载力提升机制。试验结果表明:通过后顶扩臂压浆技术,不仅提高桩土接触面积同时提升桩周土体强度,压浆效果呈圆柱型,桩臂包裹效果较好。以压浆量250mL为例,单盘后顶扩臂压浆桩承载力是普通桩的5.0倍左右,是其他桩型的2.0~3.0倍,承载力提升效果显著。单桩盘分担荷载占总荷载的80%~90%,且盘径比越大、桩盘个数越多,桩盘分担荷载越高。桩盘承载力与压浆量成线性关系,压浆量越高桩盘承载力越大。根据试验结果,建立了桩盘力学模型以及后顶扩臂压浆桩竖向承载力简化计算模型,提出桩盘承载力计算方法以及后顶扩臂压浆桩承载力计算方法。并与试验结果进行对比验证,以期可为后顶扩臂压浆桩承载力计算提供参考。To effectively improve the bearing capacity of pile foundation,the post expanded arm grouting technology and the post expanded arm grouting pile foundation are innovatively proposed.The bearing characteristics of the pile plate directly affect the bearing capacity of the pile foundation.Hence,the model tests on the mechanical properties of pile plate and bearing characteristics of post expanded arm grouting pile were carried out to analyze the load displacement change law,load sharing ratio,and pile plate failure mode.The test results indicate that this method not only increases the contact area between the pile and the soil,but also enhances the strength of the soil around the pile.The cement slurry evenly wraps the pile arm with good grouting effect.With 250mL grouting volume taken as an example,the bearing capacity of the post expanded arm grouting pile is about 5.0 times that of the ordinary pile.The bearing capacity of a single pile plate accounts for 80%⁃90%of the total load,and with the increase of the plate diameter ratio or the number of pile plates,the load carried by the pile plates shall be higher.Based on the test results,a failure mode of the pile plate was established for calculating the bearing capacity of the pile plate,and a simplified calculation method was proposed for calculating the vertical bearing capacity of the post expanded arm grouting pile.This research can be referred to by the design of pile plate and the bearing capacity calculation of the post expanded arm grouting pile.

关 键 词：桩基础 后压浆 扩臂桩 承载力 承载力提升 破坏模式 

分 类 号：TU443[建筑科学—岩土工程]