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《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

卷:

41卷

期数:

2024年06期

页码:

140-151

栏目:

岩土工程

出版日期:

2024-11-30

文章信息/Info

Title:

Test research on bearing capacity and negative friction force for single pile in collapsible loess ground

文章编号:

1673-2049(2024)06-0140-12

作者:

朱彦鹏^1,2,李芳川^1,2,成 栋^1,2,房光文³,吴林平^1,2,韦正德^1,2

(1. 兰州理工大学 土木工程学院,甘肃 兰州 730050; 2. 兰州理工大学 西部土木工程防灾减灾教育部工程研究中心,甘肃 兰州 730050; 3. 兰州城市学院 环境与城市建设学院,甘肃 兰州 730070)

Author(s):

ZHU Yanpeng^1,2, LI Fangchuan^1,2, CHENG Dong^1,2, FANG Guangwen³, WU Linping^1,2, WEI Zhengde^1,2

(1. School of Civil Engineering, Lanzhou University of Technology, Lanzhou 730050, Gansu, China; 2. Western Engineering Research Center of Disaster Mitigation in Civil Engineering of Ministry of Education, Lanzhou University of Technology, Lanzhou 730050, Gansu, China; 3. School of Environment and Urban Construction, Lanzhou City University, Lanzhou 730070, Gansu, China)

关键词:

桩基础;  承载特性;  试验研究;  自重湿陷性黄土;  负摩阻力;  特殊浸水

Keywords:

pile foundation;  bearing characteristic;  test research;  self-weight collapsible loess;  negative friction force;  special immersion

分类号:

TU473

DOI:

10.19815/j.jace.2022.12073

文献标志码:

A

摘要:

为了研究湿陷性黄土场地中土体湿陷引起的桩基承载力问题,在平凉市某工程现场利用机械成孔灌注桩(桩径0.8 m,桩长26 m)进行荷载-特殊浸水试验,对试验过程中不同深度处的桩身轴力和桩侧摩阻力进行分析。结果表明:天然状态下试验桩极限承载力大于13 200 kN,受力特性为典型的摩擦桩; 由于前期泥浆护壁施工方式对孔壁的浸水影响以及桩周土沿桩长方向上物理力学性能分布的不确定性,侧摩阻力沿深度出现多个峰值,最大值均出现在泥浆护壁以上(桩身2～6 m)位置处; 在渗水孔与渗水坑相结合的特殊浸水试验条件下,桩侧负摩阻力在浸水试验第8 d时趋于稳定,中性点在桩身8 m位置处,负摩阻力为107.6 kPa; 试验过程中桩周土沿桩长分段发生湿陷,而不是随浸水自上到下逐渐湿陷; 受到预浸水作用的试件SZH在静载试验结束后的中性点出现在桩身12 m位置处,负摩阻力为127.8 kPa,人工浸水试验主要使桩身8 m位置以上桩身轴力增大,中性点位置保持不变,表明负摩阻力受桩顶荷载、浸水方式和浸水固结时间影响显著。

Abstract:

In order to study the problem of pile foundation bearing capacity caused by the collapsibility of loess in collapsible loess ground, a load-special immersion test was conducted using mechanically drilled cast-in-place piles(with a diameter of 0.8 m and a length of 26 m)at a construction site in Pingliang City. In the experiment, multiple sensors were installed on the pile body to analyze the axial force and lateral friction resistance of the pile body at different depths during the test process. The results show that the ultimate bearing capacity of the test pile in its natural state is greater than 13 200kN, and its stress characteristics are typical of friction piles. Due to the influence of the mud wall protection construction method on the immersion of the hole wall in the early stage and the uncertainty of the physical and mechanical properties distribution of the soil around the pile along the length of the pile, there are multiple peaks in the lateral friction resistance along the depth, with the maximum values occurring above the mud wall protection(pile body is 2-6 m). Under the special immersion test conditions of combining seepage holes and seepage pits, the negative frictional resistance on the pile side tends to stabilize on the 8th day of the immersion test, with the neutral point at the 8 m position of pile body and a negative frictional resistance of 107.6 kPa. During the test, the soil around the pile collapses in sections along the length of the pile, rather than gradually collapsing from top to bottom with immersion. SZH was subjected to pre- immersion, after the static load test, the neutral point appeared at a position of 12 m of pile body, with a negative frictional resistance of 127.8 kPa. Manual immersion tests mainly increased the axial force of the pile body above 8 m, while the neutral point position remained unchanged, indicating that the negative frictional resistance was significantly affected by the pile top load, immersion method, and immersion consolidation time.

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备注/Memo

备注/Memo:

收稿日期:2023-12-21 投稿网址:http://jace.chd.edu.cn
基金项目:国家自然科学基金项目(51978321); 教育部长江学者和创新团队支持计划项目(IRT_17R51)
作者简介:朱彦鹏(1960-),男,工学博士,教授,博士生导师,E-mail:zhuyp@lut.cn。
Author resume: ZHU Yanpeng(1960-),male,PhD,professor,E-mall:zhuyp@lut.cn.

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更新日期/Last Update: 2024-12-10