基于极限载荷试验的扩底抗拔桩承载变形特性的分析

发布时间：2018-01-12 13:00

本文关键词：基于极限载荷试验的扩底抗拔桩承载变形特性的分析　出处：《岩土工程学报》2016年07期 　论文类型：期刊论文

【摘要】：结合天津于家堡南、北地下车库项目开展了2组各3根扩底抗拔桩的极限承载力试验,其中一组试桩有效桩长19 m,另一组试桩有效桩长30 m,试桩均加载至极限破坏状态。载荷试验过程中,两组试桩均对桩顶、有效桩长桩顶以及桩端位置进行了位移测试;其中有效桩长为19 m的试桩还开展了桩身轴力测试。对2组试桩成果从荷载位移曲线、桩身轴力分布、桩侧摩阻力分布规律等方面进行了分析。结合有限元数值模拟分析表明,扩底抗拔桩的承载力由等截面段桩侧摩阻力与扩大头抗力共同组成,首先由等截面段桩土侧摩阻力提供抗拔力;当上拔荷载进一步增大后,扩大头开始逐渐发挥作用,并且扩大头抗力占总承载力的比例逐步上升。极限状态下,有效桩长为19,30 m的试桩,扩大头提供的抗力占总抗拔承载力的比例分别约为50%和35%。扩大头的存在对于等截面段桩侧摩阻力的发挥影响较小。扩大头受周边土体法向力的竖向分量是扩大头抗力的主要组成部分,极限状态下,其可占扩大头抗力的70%左右。
[Abstract]:Combined with Tianjin Jiabao south, north of the underground garage project. The ultimate pullout pile bearing capacity test of 2 groups of 3 roots of belled, one group of test pile effective length 19 m, another group of test pile effective length of 30 m and pile are loaded to the ultimate failure state. Load test process two, group pile on top of the pile, effective length of pile pile and pile end position of displacement test; the effective pile length of 19 m pile has also carried out the axial force of pile test. Of the 2 groups of pile testing results from the load displacement curve, distribution of axial force of piles, pile are analyzed the side friction distribution and so on. The combination of finite element numerical simulation analysis shows that the bearing capacity of piles with enlarged base by the section of pile side friction resistance and enlarged resistance together, first by the section pile side friction with pullout force; when the uplift load increases further, gradually enlarged play a role, and The enlarged total resistance capacity. The gradual increase in the proportion of limit state, the effective pile length is 19,30 m pile, the enlarged resistance offered by the total uplift capacity ratio of approximately 50% and 35%. enlarged the presence of the play section of pile side friction influence. Vertical expansion the bulk of the surrounding soil of the normal force is the main part of the enlarged resistance, limit state, which can account for the enlarged resistance around 70%.

【作者单位】：华东建筑设计研究总院地基基础与地下工程设计研究中心;
【基金】：国家科技支撑计划课题(2012BAJ01B02)
【分类号】：TU473.1
【正文快照】： 0引言扩底抗拔桩以其良好的抗拔承载能力在工程项目中得到越来越多的应用,笔者参与设计的杭州波浪文化城和上海虹桥综合交通枢纽等深大地下工程项目中均采用了扩底抗拔桩,相比于常规等截面抗拔桩,经济效益显著。当前对扩底抗拔桩的研究以有限元数值模拟[1]、室内模型试验[2]和

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