高液限膨胀性黏土基桩工作性状的离心机试验研究

发布时间：2018-05-28 07:50

本文选题：黑棉土 + 膨胀土　；参考：《岩土工程学报》2017年10期

【摘要】：通过离心机试验研究高液限强膨胀性黑棉土地基中4根模型基桩在浸水条件下桩头位移和桩身轴力的变化规律,考虑的影响因素包括桩长、桩头荷载以及是否采用隔胀措施。通过自主设计制作的离心机内降雨装置和模型土层中的渗流通道实现黑棉土地基浸水条件。试验发现,黑棉土浸水后对桩身轴力的影响分为两阶段:前期土体刚度降低阶段,黑棉土遇水刚度降低后能提供的摩阻力明显降低,使得桩身轴力增大;后期胀拔阶段:黑棉土遇水膨胀隆起,对桩基产生向上的胀拔力,桩身轴力减小。此外,浸水引起的桩头位移变化与桩顶受荷情况密切相关:未受荷桩发生上拔位移,而荷载为625 k N的桩发生沉降位移。在桩周采取隔胀措施可以削弱甚至消除黑棉土变形对桩基的不利影响。
[Abstract]:Through centrifuge test, the variation law of pile head displacement and pile axial force of four model piles in high liquid limit and strong expansion black cotton soil foundation are studied under the condition of water immersion. The influencing factors considered include pile length, pile head load and whether to adopt expansion isolation measures. The soaking conditions of black cotton soil foundation are realized by the self-designed rainfall device in centrifuge and the seepage passage in the model soil layer. It is found that the influence of black cotton soil immersion on the axial force of pile body is divided into two stages: in the early stage of soil stiffness reduction, the frictional resistance of black cotton soil can be reduced obviously when the soil stiffness decreases, which increases the axial force of pile body; In the later stage of swelling and drawing, when the black cotton soil is swelled by water, the upward swelling force is produced and the axial force of the pile body decreases. In addition, the change of pile head displacement caused by water immersion is closely related to the load on the top of the pile: the uplift displacement occurs in the unloaded pile and the settlement displacement occurs in the pile with load of 625 KN. The negative effect of black cotton soil deformation on pile foundation can be weakened or even eliminated by taking bulging measures around the pile.
【作者单位】：清华大学土木工程安全与耐久教育部重点实验室;中国路桥工程有限责任公司;
【基金】：国家重点基础研究发展计划项目(2014CB047003)
【分类号】：TU443;TU473.1

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