2015年1月上 施工技术 第44卷第1期 CONSTRUCTIONTECHNOLOCY 73 DOI:10. 7672/sgjs2015010073 深开挖条件下抗拔桩承载性状分析与设计方法研究* 程炎焱'，吴毅彬2 (1.华北水利水电大学建筑学院，河南郑州450011；2.中船第九设计研究院工程有限公司，上海200063） [摘要】基坑开挖不可避免地引起地基应力场变化，导致桩-土界面法向应力及抗拔桩原有受力特点发生改变。
由 于实际工程条件限制，开挖后的坑底试桩往往不具备工程条件，因此掌握大面积深开挖抗拔桩承载特性，寻求简 便、实用的下部桩身承载力测试方法便显得尤为重要。
通过数值模拟开展对4类试桩方法：常规试桩、试验试桩、 套管试桩及坑底试桩的数值分析，总结不同试桩方法下抗拔单桩荷载传递规律与其工作机理。
在此基础上对本文 提出的试验试桩方法进行参数化分析，结果表明：抗拔桩有效桩长越长，开挖面处钢筋拉力与开挖后的承载力损失 比越小。
而随着开挖深度的加大，钢筋拉力的损失比基本在10%～15%变化。
在实际工程应用中，建议可按本文 提出的试验试桩方法测试下部桩身承载力，并按10%～15%的折减考虑开挖后的最终承载力。
[关键词】地下工程；桩；抗拔桩；有限元分析；承载力；试验 [中图分类号】TU375.5 [文献标识码】A [文章编号】1002-8498（2015)01-0073-05 Design and Analysis of Bearing Behaviors of Uplift Piles DuringDeepExcavation Cheng Yanyan'，Wu Yibin² （1.College ofArchitecture，NorthChinaUnitersityofWater Resources and Electrc Power，Zhengzhou， He'nan 450011,China; 2.Shipbuilding NDRI Engineering Co.,Lud.,，Shanghai 200063,China) Abstract:Bearing capacity of uplift piles would inevitably decrease owing to the change of the ground stress field and the normal stress of pile-soil interface under deep excavation.Unfortunately, due to the limitation of field conditions,it was almost impossible to field test under deep excavation.Therefore，it is important to develop a economic and replaceable test method.Here four different methods of pile load tests are simulated through the axis symmetric finite element model. Through the simulation of deep excavation, the mechanism of load transfer and settlement of the pile loaded after deep excavation are studied. Then, parametric research of pile testing used steel bar meter suggested in this paper are conducted，the results show that theeffective pile length,reinforcement meter loss ratio is small,and the excavation depth increases, the loss ratio change at the level of 10% to 15%. It is suggested that the bearing capacity of uplift piles after excavation can have a reduction in 10% to 15% in experience according to the suggested test pile used steel bar meter. Key words:underground;...
