静压管桩在实际工程中有着广泛应用,桩-土界面超孔隙水压力对静压桩的工作性能有着巨大影响。目前的研究多集中于桩周土中超孔隙水压力的分布,缺少对桩-土界面处应力的真实情况的研究。通过在桩身开孔、嵌入硅压阻式孔隙水压力传感器的方法,在黏性土体中开展了2组模型桩的室内静力压桩试验,对桩-土界面的孔隙水压力、超孔隙水压力的变化规律进行了研究。试验结果表明:利用硅压阻式传感器首次成功监测了沉桩过程中桩-土界面产生的孔隙水压力;2根试桩在沉桩过程中产生的桩-土界面孔隙水压力、超孔隙水压力均随着沉桩深度的增加而增大;同时2根试桩沉桩过程中产生的超孔隙水压力均较大,最大可达4.21 kPa,约为上覆有效土重的75%,在实际工程中需对沉桩过程中产生的较大超孔隙水压力加以重视;同一深度处的超孔隙水压力存在消散现象,随着深度的增加,消散程度逐渐减小;在实际工程中,需采取有效措施,防止超孔隙水压力过大。试验结果可为静压桩施工和桩-土界面理论研究提供参考。
Abstract
Jacked pipe has been widely used in practical engineering. The excess pore water pressure at the pile-soil interface has a great influence on the performance of jacked pile. Most current researches focus on the distribution of excess pore water pressure in the soil around the pile rather than the real situation of stress at the pile-soil interface. In this paper, by drilling holes in pile body and embedding silicone piezo-resistance pore water pressure sensor, static pile pressure test was conducted on two groups of model piles in clayey soil. The variations of pore water pressure and excess pore water pressure at the pile-soil interface were investigated. The pore water pressure generated at the pile-soil interface during pile jacking has been successfully monitored for the first time by the silica-piezo-resistance sensor. The pore water pressure and excess pore water pressure of pile-soil interface both increased with the growth of pile jacking depth. In the meantime, the excess pore water pressure generated in the process of pile jacking was relatively large, up to 4.21 kPa, which was about 75% of the effective overburden soil weight. In practical engineering, the relatively large excess pore water pressure generated in the process of pile jacking should be paid attention to. The excess pore water pressure at the same depth dissipated, and such dissipation attenuated with the increase of depth. In practical engineering, effective measures should be taken to prevent from excessive excess pore water pressure. The test results offer reference for static pressure pile construction and theoretical research on pile-soil interface.
关键词
静力压桩 /
桩-土界面 /
孔隙水压力 /
超孔隙水压力 /
硅压阻式传感器
Key words
jacked pile /
pile-soil interface /
pore water pressure /
excess pore water pressure /
silicon piezo-resistive pore water pressure sensor
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参考文献
[1] 张明义. 层状地基上静力压入桩的沉桩过程及承载力的试验研究[D]. 重庆: 重庆大学, 2001.
[2] MURTHY D S, ROBINSON R G, RAJAGOPALK. Formation of Soil Plug in Open-ended Pipe Piles in Sandy Soils[J]. International Journal of Geotechnical Engineering, 2018: 1-11. Doi: 10.1080/19386362.2018.1465742.
[3] CHOPRA M B, DARGUSH G F. Finite-element Analysis of Time-dependent Large-deformation Problems[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 1992, 16(2): 101-130.
[4] VESIC A S.Expansion of Cavities in Infinite Soil Mass[J]. Journal of the Soil Mechanics and Foundations Division, 1972, 98(3): 265-290.
[5] 唐世栋,何连生,傅 纵.软土地基中单桩施工引起的超孔隙水压力[J].岩土力学,2002,23(6):725-732.
[6] 张忠苗, 谢志专, 刘俊伟, 等. 粉土与淤质互层土中管桩压入过程孔隙水压力试验研究[J]. 岩土工程学报, 2010, 32(增刊2): 533-536.
[7] 张忠苗, 谢志专, 刘俊伟, 等. 淤质与粉质互层土中管桩沉桩过程的土压力[J]. 浙江大学学报(工学版), 2011, 45(8): 1430-1434.
[8] AZZOUZ A S, MORRISON M J. Field Measurements on Model Pile in Two Clay Deposits[J]. Journal of Geotechnical Engineering, 1988, 114(1): 104-121.
[9] 李镜培, 张凌翔, 李 林. 饱和黏土中静压桩桩周土体强度时效性分析[J]. 哈尔滨工业大学学报, 2016, 48(12): 89-94.
[10]李镜培, 李 林, 孙德安, 等. 基于CPTU测试的K0固结黏土中静压桩时变承载力研究[J]. 岩土工程学报, 2017, 39(2): 193-200.
[11]高子坤, 施建勇. 饱和黏土中沉桩挤土形成超静孔压分布理论解答研究[J]. 岩土工程学报, 2013, 35(6): 1109-1114.
[12]王 伟, 宰金珉, 王旭东. 沉桩引起的三维超静孔隙水压力计算及其应用[J]. 岩土力学, 2004, 25(5): 774-777.
[13]张建新, 赵建军, 孙世光. 群桩沉桩引起的超孔隙水压力的室内模型及试验分析[J]. 工业建筑, 2009, 39(1): 76-78.
[14]朱向荣, 何耀辉, 徐崇峰, 等. 饱和软土单桩沉桩超孔隙水压力分析[J]. 岩石力学与工程学报, 2005, 24(增刊2): 5740-5744.
[15]李 钰, 蔡超君. 静压沉桩及锤击沉桩对饱和砂土中超孔隙水压力的影响[J]. 科学技术与工程, 2015, 15(35): 228-232.
[16]张亚国, 李镜培. 静压沉桩引起的土体应力与孔压分布特征[J]. 上海交通大学学报, 2018, 52(12): 1587-1593.
[17]王永洪, 张明义, 张春巍, 等. 静压桩贯入试验硅压阻式传感器的研制及应用[J]. 压电与声光, 2017(6): 52-56.
[18]李雨浓, LEHANE B M , 刘清秉. 黏土中静压沉桩离心模型[J]. 工程科学学报, 2018, 40(3): 285-292.
[19]GB/T 50123—1999,土工试验方法标准[S]. 北京: 中国计划出版社, 1999.
[20]JGJ 94—2008,建筑桩基技术规范[S]. 北京: 中国建筑工业出版社, 2008.
[21]OVESEN N K. The Scaling Law Relationship — Panel Discussion[C]∥Proceedings of the 7th European Conference on Soil Mechanics and Foundation Engineering. Brighton, UK. 1979: 319-323.
[22]徐光明, 章为民. 离心模型中的粒径效应和边界效应研究[J]. 岩土工程学报, 1996, 18(3): 80-86.
[23]王 伟. 打桩引起的超静孔隙水压力预测及其应用[D]. 南京: 南京工业大学, 2002.
[24]姚笑清, 胡中雄. 饱和软粘土中沉桩引起的孔隙水压力估算[J]. 岩土力学, 1997, 18(6): 31-35.
[25]PESTANA J M, HUNT C E, BRAY J D. Soil Deformation and Excess Pore Pressure Field around a Closed-ended Pile[J]. Geotechnical and Geoenvironmental Engineering, 2002, 128(1): 1-12.
[26]吴旭东. 静压管桩施工过程监测与减小超孔隙水压力的工程实例[J]. 常州工学院学报, 2008, 21(增刊1): 171-173.
基金
国家自然科学基金项目(51778312, 51809146);山东省重点研发计划项目(2017GSF16107, 2018GSF117010,2018GSF117008)
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