| 考虑固结过程的单桩负摩擦数值模型 |
| 杨军, 张大峰 |
| 清华大学 土木工程系, 土木工程安全与耐久教育部重点实验室, 北京 100084 |
| Numerical model for a single pile with negative friction and soil consolidation |
| YANG Jun, ZHANG Dafeng |
| Key Laboratory of Civil Engineering Safety and Durability of the Ministry of Education of China, Department of Civil Engineering, Tsinghua University, Beijing 100084, China |
摘要:
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| 摘要该文旨在建立考虑地基土固结过程的桩基负摩擦计算模型。基于岩土工程有限元软件Plaxis建立有限元模型, 并使用换土法模拟离心机加速前土的欠固结状态, 进而模拟试验负摩擦发展过程。计算结果表明: 该模型计算精度较高, 固结完成时远端土的沉降计算误差为6.8%, 桩基沉降和轴力的计算误差分别为34.7%和18.3%; 此外, 不同固结时刻下的超静孔压以及桩基最大轴力相对值与离心机试验数据吻合, 且桩基轴力均近似与时间的平方根成线性关系。该模型可为考虑地基图固结的桩基负摩擦问题的计算提供参考。 | |||
| 关键词 ：单桩,负摩擦,固结,数值模型,离心机试验 | |||
| Abstract：This paper describes a numerical model for predicting the pile foundation conditions with negative friction and soil consolidation. The geotechnical finite element software Plaxis was used to create the numerical model and soil replacement method to simulate initial soil state before acceleration of the centrifuge. Then, the development of negative friction was simulated, and the results are quite accurate. The predicted soil settlement error after consolidation is within 6.8% of the test data, the pile settling error is within 34.7% and the piling force error is within 18.3%. In addition, the excess pore pressure and relative maximum axial piling force are consistent with centrifuge test data for various consolidation times and axial force is approximately linearly related with the square root of time. This model provides reference data for calculating single pile foundations with negative friction and soil consolidation. | |||
| Key words：single pilenegative frictionsoil consolidationnumerical modelcentrifuge test | |||
| 收稿日期: 2013-10-28 出版日期: 2016-01-12 | |||
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| 引用本文: |
| 杨军, 张大峰. 考虑固结过程的单桩负摩擦数值模型[J]. 清华大学学报（自然科学版）, 2015, 55(12): 1276-1280. YANG Jun, ZHANG Dafeng. Numerical model for a single pile with negative friction and soil consolidation. Journal of Tsinghua University(Science and Technology), 2015, 55(12): 1276-1280. |
| 链接本文: |
| http://jst.tsinghuajournals.com/CN/10.16511/j.cnki.qhdxxb.2015.24.002或 http://jst.tsinghuajournals.com/CN/Y2015/V55/I12/1276 |
图表:
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| 表1 模型中土的参数 |
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| 图1 超静孔压随深度的分布 |
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| 图2 固结完成桩身轴力曲线 |
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| 表3 固结完成后的结果对比 |
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| 图3 超静孔压随时间的变化曲线 |
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| 图4 轴力随时间的发展 |
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| 图5 不同固结时刻桩基轴力分布曲线 |
参考文献:
| [1] Fellenius B H. Results from long-term measurement in piles of drag load and downdrag [J]. Canadian Geotechnical Journal, 2006, 43(4): 409-430. [2] 周景星. 基础工程 [M]. 北京: 清华大学出版社, 2007: 143-150. ZHOU Jingxin. Foundation Engineering [M]. Beijing: Tsinghua University Press, 2007: 143-150. [3] Bjerin L. Negative Skin Friction on Long Precast Piles Driven in Clay [R]. Stockholm, Swedish: Swedish Geotechnical Institute, 1977. [4] GB 50112-2013. 膨胀土地区建筑技术规范 [S]. 北京: 中国建筑工业出版社, 2012.GB 50112-2013. Technical Code for Buildings in Expansive Soil Regions [S]. Beijing: China Architecture & Building Press, 2012. [5] Fellenius B H. Negative skin friction and settlement of piles [C]// Second International Seminar, Pile Foundations. Singapore: Nanyang Technological Institute, 1984: 12. [6] LIU Jinyuan, GAO Hongmei, LIU Hanlong. Finite element analyses of negative skin friction on a single pile [J]. Acta Geotechnica, 2012, 7(3): 239-252. [7] Lam S Y, Ng C W, Leung C F, et al. Centrifuge and numerical modeling of axial load effects on piles in consolidating ground [J]. Canadian Geotechnical Journal, 2009, 46(1): 10-24. [8] Ng C W, Poulos H G, Chan V S, et al. Effects of tip location and shielding on piles in consolidating ground [J]. Journal of Geotechnical and Geoenvironmental Engineering, 2008, 134(9): 1245-1260. [9] 徐长节, 耿雪玉, 蔡袁强. 任意荷载下欠固结地基的非线性一维固结 [J]. 岩土力学, 2006(03): 389-394.XU Changjie, GENG Xueyu, CAI Yuanqiang. One-dimensional nonlinear consolidation of under consolidation clay under arbitrary loadings [J]. Rock and Soil Mechanics, 2006(03): 389-394. [10] Brinkgreve R B J. PLAXIS 2D 2011 . (2013- 05-01), http://www.plaxis.nl/. [11] WANG Rui, Brandenberg S J. Beam on nonlinear Winkler foundation and modified neutral plane solution for calculating downdrag settlement [J]. Journal of Geotechnical and Geoenvironmental Engineering, 2013, 139(9), 1433-1442. |
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