| 摘要: |
| 结合高速公路桥头深厚软基现场试验段工程，对比了几种管桩复合地基单桩有限元数值建模方法，认为轴对称接触有限元模型可以较准确地反映路堤下管桩复合地基的基本性状。基于数值分析结果，详细探讨了管桩复合地基的受力特性和变形分布。结果表明：填土越高，桩顶承台应力集中越显著；桩土应力比与高距比、桩土沉降差之间均存在较好的正相关线性关系。填筑结束，带承台管桩承担了80%的路堤荷载，管桩外侧摩阻力承担了超过90%的承台受荷；与在天然地基上堆载相比，大部分荷载通过管桩传递到压缩性相对较小的深层地基中，管桩复合地基的附加应力分布得到了优化，桩长范围内地基的压缩率及压缩量大幅减小，管桩复合地基的总沉降量仅为相应天然地基堆载沉降量的185%，深厚软基的总沉降减幅为435 mm。 |
| 关键词: 管桩复合地基 轴对称模型 荷载分配 荷载传递 压缩变形 压缩率 |
| DOI： |
| 分类号:TU472 |
| 基金项目:国家自然科学基金资助项目（51579152）； 中央级公益性科研院所基本科研业务费专项基金资助项目（Y316011， Y316021）； 浙江省宁波市交通科技委科技计划项目（201312） |
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| Numerical simulation of pipe pile composite foundation of deep soft foundation under embankment |
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JIANG Yanbin1, HE Ning1, LIN Zhiqiang2, YAO Mingshuai1, LI Wenxuan1
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1.Nanjing Hydraulic Research Institute, Nanjing;2.Fujian Academy of Building Research, Fuzhou
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| Abstract: |
| Combined with the in-situ test results of the piled embankment with deep soft foundation at the bridge-head of expressway, several axisymmetric finite element numerical modeling methods for single pipe pile in composite foundation are compared and verified. It is considered that the axisymmetric contact finite element model can accurately reflect the basic properties of the pipe pile composite foundation under embankment. The mechanical characteristics and deformation distribution of the piled embankment composite foundation are discussed in detail based on the numerical analysis results. The numerical calculation results show that the higher the fill is, the more prominent the stress concentration is at the top of the pile cap. The pile-soil stress ratio and the ratio of embankment height to pile spacing, as well as the settlement difference between the pile and soil, shows that there have the relatively good positive linear relationships. At the end of embankment filling, 80% of the embankment load is carried by the pipe pile with the cap, and more than 90% of the load on the cap is undertaken by lateral friction resistance of the pile. Most of the load is transferred to the deep foundation with relatively low compressibility compared with surcharge on the natural foundation, and the additional stress distribution of the rigid pile composite foundation is optimized, both of the compression rate and compression of the foundation are significantly reduced within the length of pile. The total settlement of pipe pile composite foundation is only 18.5% of the corresponding natural foundation with the same load, and the total settlement of the deep soft foundation is reduced by 435 mm. |
| Key words: composite foundation with pipe pile axisymmetric model load distribution load transfer compression deformation compression ratio |
