|
|
|
| EXPERIMENTAL STUDY OF BEHAVIOR COMPARISON OF GROUTED AND NON-GROUTED UPLIFT PILES IN SOFT SOIL |
(1. Institute of Geotechnical Engineering，Zhejiang University，Hangzhou，Zhejiang 310058，China；
2. Key Laboratory of Soft Soils and Geoenvironmental Engineering，Ministry of Education，Zhejiang University，
Hangzhou，Zhejiang 310058，China) |
|
|
|
|
Abstract Based on the uplift static test of grouted and non-grouted uplift piles at a building site of Xiaoshan in Hangzhou area，it¢s found that pile-end post grouting technology can significantly reduce the pile tip settlement and increase the ultimate uplift resistance of pile. The ultimate uplift resistance of the pile with post-grouted is 1.25 times of the pile without post-grouted and the maximum tension value of pile shaft is about 91.5% of the displacement at the pile head. The axial forces of grouted pile shaft and non-grouted pile shaft both decrease gradually with depth and the measured end axial forces of piles are near zero during the whole loading cycle. The friction resistance of grouted pile within the climb height of grouts of 16.9 m has a large increase and the maximum value is 83.3%，because the mudcake near the pile end is solidified by grouting and the larger friction resistance are mobilized. Based on the vertical enhancement body height of grouted uplift piles calculated by the formula of climb height of grouts，a new simple formulation for calculating the ultimate bearing capacity of uplift piles with pile-end post grouting is proposed by considering dead weight of piles. Through the back analysis and calculation，it is shown that the value range of the uplift reduction coefficients of non-grouted piles is 0.65–0.80；and the value range of lateral resistance enhancement coefficients of grouted piles is 1.33–1.83. The calculation method and its results can be applied to the preliminary design and practical engineering.
|
|
Received: 25 June 2010
|
|
|
|
| [1] 魏建华，徐 枫，吴 超. 桩侧后注浆与扩底抗拔桩承载特性研究[J]. 地下空间与工程学报，2009，5(增2)：1 727–1 730.(WEI Jianhua，XU Feng，WU Chao. Analysis of uplift behavior of piles with side post-grouting and enlarged base[J]. Chinese Journal of Underground Space and Engineering，2009，5(Supp.2)：1 727–1 730.(in Chinese))
[2] 张 武，高文生. 抗拔桩后注浆技术及其应用[J]. 岩土工程技术，2008，22(1)：31–35.(ZHANG Wu，GAO Wensheng. Post grouting technology of uplift pile and its application[J]. Geotechnical Engineering Technique，2008，22(1)：31–35.(in Chinese))
[3] 王之军. 等截面竖向单桩抗拔承载力试验研究及变形非线性分析[博士学位论文][D]. 北京：中国地质大学，2006.(WANG Zhijun. Experimental study of anti-pulling capacity and nonlinear deformation analysis of vertical single uplift piles with equal section[Ph. D. Thesis][D]. Beijing：China University of Geosciences，2006.(in Chinese))
[4] 中华人民共和国行业标准编写组. JGJ 106–2003建筑基桩检测技术规范[S]. 北京：中国建筑工业出版社，2003.(The Professional Standards Compilation Group of People′s Republic of China. JGJ 106–2003 Technical code for testing of building foundation piles[S]. Beijing：China Architecture and Building Press，2003.(in Chinese))
[5] 舒士霖. 钢筋混凝土结构[M]. 杭州：浙江大学出版社，2003.(SHU Shilin. Reinforced concrete structure[M]. Hangzhou：Zhejiang University Press，2003.(in Chinese))
[6] 袁加贝，孙进忠，李丛昀. 抗拔桩实验的桩身受力分析[J]. 土工基础，2007，21(2)：25–30.(YUAN Jiabei，SUN Jinzhong，LI Congyun. Analysis of forces of pile shafts in uplift pile tests[J]. Soil Engineering and Foundation，2007，21(2)：25–30.(in Chinese))
[7] 张忠苗，张广兴，吴庆勇，等. 钻孔桩泥皮土与桩间土性状试验研究[J]. 岩土工程学报，2006，28(6)：695–699.(ZHANG Zhongmiao，ZHANG Guangxing，WU Qingyong，et al. Studies of characteristics of mudcake and soil between bored piles[J]. Chinese Journal of Geotechnical Engineering，2006，28(6)：695–699.(in Chinese))
[8] 张忠苗. 灌注桩后注浆技术及工程应用[M]. 北京：中国建筑工业出版社，2009.(ZHANG Zhongmiao. Post grouting technology of cast-in-place piles and its engineering application[M]. Beijing：China Architecture and Building Press，2009.(in Chinese))
[9] 张忠苗. 桩基工程[M]. 北京：中国建筑工业出版社，2007.(ZHANG Zhongmiao. Pile foundation engineering[M]. Beijing：China Architecture and Building Press，2007.(in Chinese))
[10] 张 雁，刘金波. 桩基手册[M]. 北京：中国建筑工业出版社，2009. (ZHANG Yan，LIU Jinbo. Handbook for pile foundations[M]. Beijing：China Architecture and Building Press，2009.(in Chinese))
[11] 张忠苗，邹 健. 桩底劈裂注浆扩散半径和注浆压力研究[J]. 岩土工程学报，2008，30(2)：181–184.(ZHANG Zhongmiao，ZOU Jian. Study of penetration radius and grouting pressure in fracture grouting[J]. Chinese Journal of Geotechnical Engineering，2008，30(2)：181–184.(in Chinese))
[12] 阮文军. 注浆扩散与浆液若干基本性能研究[J]. 岩土工程学报，2005，27(1)：69–73.(RUAN Wenjun. Research on diffusion of grouting and basic properties of grouts[J]. Chinese Journal of Geotechnical Engineering，2005，27(1)：69–73.(in Chinese))
[13] 邹 健，张忠苗. 桩端后上返高度及桩顶冒浆处理[J]. 岩土力学，2010(待刊).(ZOU Jian，ZHANG Zhongmiao. Climb height and overflow of grouts in pile-end post grouting[J]. Rock and Soil Mechanics，2010(to be published).(in Chinese))
[14] 曾国熙，叶政青，冯国栋. 桩基工程手册[M]. 北京：中国建筑工业出版社，1995：139–222.(ZENG Guoxi，YE Zhengqing，FENG Guodong. Handbook for pile foundations[M]. Beijing：China Architecture and Building Press，1995：139–222.(in Chinese))
[15] 中华人民共和国行业标准编写组. JGJ 94–2008建筑桩基技术规范[S]. 北京：中国建筑工业出版社，2008.(The Professional Standards Compilation Group of People′s Republic of China. JGJ 94–2008 Technical code for building pile foundation[S]. Beijing：China Architecture and Building Press，2008.(in Chinese)) |
|
|
|
2010, Vol. 29 
