|本期目录/Table of Contents|

 Zheng Gang,Wang Fanjun,Sun Hongbin,et al.Surface Settlement Caused by Borehole Group Effect of CFG Piles in Soft Soil[J].Journal of Tianjin University,2017,(08):796-805.[doi:10.11784/tdxbz201610080]





Surface Settlement Caused by Borehole Group Effect of CFG Piles in Soft Soil
郑刚12 王凡俊2 孙宏宾2 程雪松12 雷华阳12 张涛2
1. 滨海土木工程结构与安全教育部重点实验室(天津大学),天津 300072;2. 天津大学建筑工程学院,天津 300072
Zheng Gang12 Wang Fanjun2 Sun Hongbin2 Cheng Xuesong12 Lei Huayang12 Zhang Tao2
1.Key Laboratory of Coast Civil Structure Safety(Tianjin University), Ministry of Education, Tianjin 300072, China
2.School of Civil Engineering, Tianjin University, Tianjin 300072, China
CFG桩 群孔 地表沉降 软土
CFG piles borehole group surface settlement soft soil
在软土地区CFG桩施工形成的大量空桩孔如不及时回填会产生群孔效应, 造成地表沉降, 进而威胁邻近建筑物、隧道及管线等基础设施的安全.本文基于某工程实测结果, 利用有限元研究了单孔和多孔情况下引起的地表沉降情况及多孔叠加机理, 提出了多孔合并法来解决实际工程中数量庞大的桩孔较难模拟问题, 并对群孔效应引发周边严重沉降的工程进行了模拟分析.研究结果表明, 单孔引发的沉降值主要受孔径影响, 呈正相关; 沉降最大值位置主要受孔深影响, 呈线性正相关.孔心距较小时, 空孔周边土体中水平和竖向上的土应力拱的相互影响与削弱导致每个空孔的内缩变形均大于单孔时的变形值, 是导致群孔效应引发周边严重沉降的主要原因.群孔引发的沉降与孔数呈对数关系, 孔数增大到一定值时沉降不再显著增长.所提出的多孔合并的群孔研究方法及合并转化系数γ, 为进一步研究群孔效应奠定了基础.
A large number of hollow boreholes left in the soil strata during the construction of CFG piles can lead to the borehole group effect and cause the surface settlement in soft soil area,which threats the safety of adjacent buildings,tunnels and municipal pipes. Based on a case study,the surface settlements caused by single and group hollow boreholes and the mechanism underlying the effect of boreholes on each other were investigated by the finite element method(FEM). To simulate the massive pile holes in practical engineering,a method of multi-hole merging is proposed. Additionally,the case was modelled by FEM using this method,and the settlements derived by the numerical simulation and field measurement were compared and analyzed. Thus the settlement mechanism is revealed. The results show that for the single borehole,the settlement value is mainly influenced by and increases linearly with the hole diameter. The distance between the maximum settlement position and the hole is mainly influenced by and increases linearly with the hole depth. The shrinkage of each hollow borehole becomes greater than that of the single hole because the horizontal and vertical stress arching surrounding each hole influences and destroys each other when the hole center distance is relatively small. It is an important mechanism for the borehole group effect. For the borehole group,the settlement increases logarithmically as the hole number increases,and when the hole number is larger than a certain value,the settlement remains unchanged. Furthermore,the method of multi-hole merging and the conversion coefficient γ proposed in the paper can provide a reference for the further study on the borehole group effect.


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收稿日期: 2016-10-20; 修回日期: 2017-02-15.
作者简介: 郑刚(1967—), 男, 博士, 教授, zhenggang1967@163.com.
通讯作者: 程雪松, cheng_xuesong@163.com.
基金项目: 国家自然科学基金资助项目(51508382, 41630641); 中国博士后科学基金资助项目(2014M561186).
Supported by the National Natural Science Foundation of China(Nos. 51508382 and 41630641)and the China Postdoctoral Science Found-
tion(No. 2014M561186).
更新日期/Last Update: 2017-08-10