软土地区挤扩支盘桩竖向承载特性研究  

Study of Vertical Bearing Capacity of Squeezed Branch Pile in Soft Soil Area

作　　者：易浩 张坤标 陈页开[2] 汪益敏[2] YI Hao;ZHANG Kun-biao;CHEN Ye-kai;WANG Yi-min(Guangdong Transportation Construction Engineering Quality Test Center, Guangzhou 510420, China;School of Civil Engineering and Transportation, South China University of Technology, Guangzhou 510641, China)

机构地区：[1]广东省交通运输建设工程质量检测中心,广东广州510420 [2]华南理工大学土木与交通学院,广东广州510641

出　　处：《世界桥梁》2021年第5期79-86,共8页World Bridges

基　　金：广东省交通科技项目(2020)。

摘　　要：为研究软土区挤扩支盘桩承载性能,以汕头某市政道路跨线桥试桩(桩长40.88 m的挤扩支盘桩)为背景,通过现场静载试验获得试桩的荷载~沉降曲线、桩身轴力分布规律,利用PLAXIS 3D有限元分析软件模拟挤扩支盘桩和等体积直孔灌注桩2种桩型的单桩静载试验,对比分析二者承载特性和破坏模式。结果表明:在单桩静载试验中施加预估的设计最大荷载后,挤扩支盘桩表现出良好的沉降控制能力且仍具有一定承载安全储备;通过数值模拟静载试验进一步施加荷载,挤扩支盘桩的承载能力优于等体积直孔灌注桩,且荷载量级越大挤扩支盘桩承载优势越显著;挤扩支盘桩桩顶荷载主要由支盘端承力承担,支盘间桩侧阻力发挥优先级低于支盘端承力;模拟极限荷载条件下,软土区挤扩支盘桩存在“单盘破坏”和“圆柱式剪切破坏”2种潜在破坏模式。Based on the engineering practice of an urban overpass in Shantou,the load bearing behavior of the squeezed branch pile in the soft soil area is studied.The trial pile,which is a 40.88 m squeezed branch pile,was examined.In-situ static load test was carried out to obtain the load-settlement curves of the trial pile and distribution law of axial forces in pile shaft.The finite element soft ware PLAXIS 3D was used to simulate mono-pile static load tests of two types of piles,including the squeezed branch pile and the vertical bored pile of equal volume to the squeezed branch pile.The load bearing behaviors and failure modes of the two types of piles were compared and analyzed.In the test,when the maximum design loads were applied,the squeezed branch pile exhibited good settlement control capacity and owned a degree of safety margin.When additional loads that were figured out from numerical simulation were further applied,the squeezed branch pile presented superior load bearing capacity,compared to the vertical bored pile with equal volume,and the load bearing capacity of the squeezed branch pile was more outstanding under excessive loads.The loads on the top of the squeezed branch pile are mainly accommodated by the end-bearing capacity of the branches,and in terms of the precedence level,the side frictions among branches are behind the end-bearing capacity of the branches.Under the ultimate loading condition in the simulation,the squeezed branch pile in the soft soil area is likely to undergo“single branch failure”and/or“cylindrical shear failure”.

关 键 词：桥梁基础 挤扩支盘桩 软土地区 竖向承载能力 破坏模式 静载试验 数值模拟 

分 类 号：U443.15[建筑科学—桥梁与隧道工程] U441[交通运输工程—道路与铁道工程]