循环加载下X形桩竖向承载特性模型试验研究

发布时间：2018-05-02 15:11

本文选题：大比尺模型试验 + X形桩　；参考：《岩土力学》2016年S1期

【摘要】：实际工程中桩基经常受到各种动荷载作用,如高铁路基中的加固桩长期承受列车行车时产生的循环动荷载作用,桩基在循环荷载作用下的承载特性研究对动荷载下的工程设计至关重要。X形桩是一种在传统圆形截面桩基础上发展而来的新型异性桩技术,其承载机制不同于传统圆形截面桩。为了深入研究X形桩在循环荷载作用下的动力特性和荷载与沉降规律,开展了砂土中X形桩竖向循环加载大比尺模型试验。试验结果表明,随着循环加载的进行,X形桩顶产生累计沉降,且循环荷载比越大,加载频率越高,桩顶沉降越快;循环加载初期,X形桩顶动刚度降低,桩身轴力响应增大,桩侧摩阻力发生弱化,之后逐渐趋于稳定,且桩身下半段侧摩阻力较大;在同等加载条件下X形桩与等截面圆形桩相比,承受动荷载能力较强,桩侧摩阻力较大,长期循环加载作用下产生的累计位移较小。研究结果可为X形桩在动荷载作用下的工程设计提供参考依据。
[Abstract]:In practical engineering, pile foundations are often subjected to various dynamic loads, such as the reinforcement piles in high-speed railway subgrade, which are subjected to cyclic dynamic loads caused by train running for a long time. Research on the bearing characteristics of pile Foundation under cyclic load; X pile is a new type of anisotropic pile technology developed on the basis of traditional circular section pile, and its bearing mechanism is different from that of traditional circular section pile. In order to deeply study the dynamic characteristics of X-shaped pile under cyclic load and the law of load and settlement, a large scale model test of X-shaped pile under vertical cyclic loading in sandy soil was carried out. The experimental results show that with the cyclic loading, the accumulative settlement of X shaped pile is produced, and the higher the cyclic load ratio is, the higher the loading frequency is, the faster the settlement of the pile top is, the lower the dynamic stiffness of the top of the pile is in the early stage of cyclic loading, the greater the axial force response of the pile body is. The frictional resistance of the pile side becomes weaker, then tends to be stable, and the friction resistance of the bottom half of the pile body is larger, compared with the circular pile with equal section under the same loading condition, the resistance of the X shaped pile is stronger than that of the circular pile with the same section, and the friction resistance of the pile side is larger than that of the circular pile with the same section. The accumulative displacement caused by long-term cyclic loading is smaller. The results can provide a reference for the engineering design of X-shaped pile under dynamic load.
【作者单位】：河海大学岩土力学与堤坝工程教育部重点实验室;河海大学土木与交通学院;重庆大学土木工程学院;
【基金】：国家自然科学基金高铁联合基金重点项目(No.U1134207);；长江学者和创新团队发展计划(IRT1125) 国家自然科学基金(No.51378177)~~
【分类号】：TU473.1

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