大面积填土场地深厚软土中预应力管桩下拉荷载现场试验

余建飞; 张静; 杨石飞

doi:10.13204/j.gyjzG20110501

大面积填土场地深厚软土中预应力管桩下拉荷载现场试验

doi: 10.13204/j.gyjzG20110501

1. 浙江石油化工有限公司, 浙江舟山 316021;
2. 上海勘察设计研究院(集团)有限公司, 上海 200093

详细信息

作者简介:
余建飞,男,1974年出生,高级工程师。

通讯作者:
张静,女,zhangjing@sgidi.com。

计量
- 文章访问数: 78
- HTML全文浏览量: 10
- PDF下载量: 5
- 被引次数: 0
出版历程
- 收稿日期: 2020-11-05
- 网络出版日期: 2022-04-24

Field Tests of Drag Loads on Prestressed Pipe Piles in Deep Soft Soil of Large Fill Sites

1. Zhejiang Petroleum & Chemical Co., Ltd., Zhoushan 316021, China;
2. SGIDI Engineering Consulting (Group) Co., Ltd., Shanghai 200093, China

摘要

摘要: 舟山某石化基地工程，场地大面积填土厚度达10 m，填土以下深厚软土厚度达50 m。在场地超载预压卸载后对新打设的预应力管桩进行下拉荷载测试，研究桩土相对位移以及桩土相对位移速率对试桩下拉荷载、负摩阻力系数和中性点的影响。结果表明：下拉荷载与桩土相对位移呈正相关性，下拉荷载增长速率随桩土相对位移速率减小而减小，当桩土相对位移速率减小至0.1~0.2 mm/d时，下拉荷载趋于稳定；根据单桩悬吊法测得的不同桩长桩身负摩阻力平均值，提出负摩阻力系数及中性点的计算方法。实测表明：随着时间增长，负摩阻力愈大，但远小于正摩阻力极限值，中性点深度愈大，至一定深度后趋于稳定。最后，基于JGJ 94—2018《建筑桩基技术规范》负摩阻力综合安全系数法所建议的单桩承载力特征值验算了预制桩，验算表明桩基满足工程安全要求。
- 下拉荷载试验 /
- 大面积填土 /
- 深厚软土 /
- 负摩阻力系数 /
- 中性点 /
- 桩基承载力
Abstract: Field tests of drag loads for prestressed pipes pile were performed in a petrochemical engineering in Zhoushan in which the backfill and underlying soft soil were 10 m and 50 m respectively. After unloading of surcharge preloading, prestressed pipe piles with different length were piled. Based on field tests, influences of relative displacement and relative displacement rates between piles and soil on drag loads, coefficients of negative friction and neutral points were studied. The results showed that there existed a positive correlation between drag loads and relative displacement between piles and soil. Growth rates of drag loads decreased with decrease of relative displacement rates between piles and soil. When relative displacement rates between piles and soil reduced to 0.1 to 0.2 mm/d, drag loads tended to be stable. Average values of negative friction could be tested by the suspension method. The calculation methods about coefficients of negative friction and neutral points were proposed according to the measured values in different pile length. The field test results showed that negative friction increased with time and the depth of neutral points in piles would increase as well. In the end, the increase of the depth for neutral points tended to be stable,negative friction was much less than the ultimate value of positive friction. The characteristic value of the bearing capacity of single piles was checked by the comprehensiely safe factor method considering the negative friction from JGJ 94-2018 Technical Code for Building Pile Foundation, the results showed the piles could meet safety requirements.
- field test of drag load /
- large filling /
- deep soft soil /
- coefficient of negative friction /
- neutral point /
- bearing capacity of pile foundation

HTML全文

参考文献(27)

[1]	TERZAGHI K, PECK R B, MESRI G. Soil mechanics in engineering practice[M]. 3rd ed. New York:John, Wiley & Sons, 1996.
[2]	唐漾. 单桩负摩阻力形成机理分析及单桩竖向承载力计算[D].湘潭:湘潭大学,2013.
[3]	张晓峰.桩基负摩阻力的试验研究[D].上海:同济大学.2007.
[4]	胡瑞庚. 高填方夯实地基桩侧负摩阻力计算方法研究[D].青岛:青岛理工大学,2018.
[5]	孔纲强,杨庆,杨钢,等.负摩阻力引起的桩身下拽力和桩顶下拽位移研究进展[J].河海大学学报(自然科学版),2010,38(4):411-417.
[6]	SEED H B, REESE L C. The action of soft clay along friction piles[J]. Transactions of the ASCE,1957, 122(1):731-754.
[7]	佐藤悟. 基础坑の支持の力学な机构[J]. 土工技術, 1965, 20:1-5.
[8]	ENDO M, MINOU A, KAWASAKI T, et al. Negative skin friction acting on steel piles in clay[C]//Proceedings 7th International Conference on Soil Mechanics and Foundation Engineering. 1969:85-92.
[9]	陆明生. 桩基表面负摩擦力的试验研究及经验公式[J]. 水运工程,1997(5):54-58.
[10]	LEE C J, CHEN H T, WANG W H. Negative skin friction on piles due to excessive ground water withdrawal[C]//International Conference of Centrifuge.1998:513-518.
[11]	夏力农,雷鸣,聂重军.桩顶荷载对负摩阻力性状影响的现场试验[J].岩土力学,2009,30(3):664-668.
[12]	于连鑫,崔高航.桩基负摩阻力特性研究进展综述[J].科技创新与应用,2017(35):181,183.
[13]	马学宁, 张沛云, 贾喜翠等.不同桩端下卧层桩基负摩阻力模型试验研究[J]. 铁道工程学报, 2017(1):11-16.
[14]	李河.涂层对钢管桩身负摩阻力影响的试验研究[D].郑州:河南大学,2018.
[15]	张建新,岳晓鹏,刘举,等.软土次固结阶段桩侧负摩阻力变化规律研究[J].工程地质学报,2017,25(3):692-698.
[16]	周为.新近填土中桩基负摩阻力的室内模型试验研究[D].成都:西南交通大学,2019.
[17]	王殿龙,刘凯,尚玉杰,等.考虑压实度的填土场基桩负摩阻力试验[J].人民长江,2019,50(8):193-198.
[18]	WALKER L K, DARVALL P, LE P. Drag-down on coated and uncoated piles[C]//Proceedings of the 8th International Conference on Soil Mechanics and Foundation Engineering.1973:257-262.
[19]	马时冬.桩身负摩阻力的现场测试与研究[J].岩土力学,1997(1):8-15,24.
[20]	INDRARATNA B, BALASUBRAMANIAM A S, PHAMVAN P. Development of negative skin friction on driven piles in soft bangkok clay[J]. Canadian Geotechnical Journal,1992,29(3).DOI: 10.1139/t92-044.
[21]	叶观宝,郑文强,张振.大面积填土场地中摩擦型桩负摩阻力分布特性研究[J].岩土力学,2019,40(增刊1):440-448.
[22]	肖俊华, 袁聚云, 赵锡宏. 桩基负摩擦力的下拉荷载与时间关系研究[J]. 岩土力学, 2009, 30(9):2779-2782.
[23]	张浜申. 填海造地工程软基固结沉降与桩基负摩阻力研究[D].合肥:安徽理工大学,2018.
[24]	方越. 填海快速成陆场地桩基负摩阻力分布特性研究[D]. 合肥:安徽理工大学,2019.
[25]	黄雪峰,陈正汉,哈双,等.大厚度自重湿陷性黄土中灌注桩承载性状与负摩阻力的试验研究[J].岩土工程学报,2007(3):338-346.
[26]	JOHANNESSEN L J, BJERRUM L. Measurement of the compression of a steel pile to rock due to settlement of the surrounding clay[C]//Proceedings of the Sixth International Conference on Soil Mechanics and Foundation Engineering. 1965:261-264.
[27]	中华人民共和国住房和城乡建设部.建筑桩基技术规范:JGJ 94-2018[S].北京:中国建筑工业出版社,2008.