土工基础

›› 2014, Vol. 28 ›› Issue (2): 1-04.

• 工程实录 •    下一篇

深基坑开挖对扩底抗拔桩承载性能的影响

陈 芦   

  1. （上海中环投资开发（集团）有限公司，上海 200060）
  • 收稿日期:2014-02-25 出版日期:2014-04-21 发布日期:2014-04-25
  • 作者简介:陈芦（1975-），男，大学本科，高级工程师，研究方向为房地产开发管理。

Effects of Deep Excavation on the Uplift Resistance of Underreamed Drilled Shafts

CHEN Lu   

  1. (Shanghai Zhonghuan Investment Development (Group) Co., Ltd., Shanghai 200060)
  • Received:2014-02-25 Online:2014-04-21 Published:2014-04-25

摘要： 有限元数值模拟研究表明，基坑开挖土体回弹在扩底桩桩身引起较大的轴力，桩身的中性点位置靠近扩底端。在考虑基坑开挖影响时，桩身的真实轴力远较未考虑基坑开挖影响时大，且轴力的最大点并非在桩顶加载部位，在设计时应充分注意到这一特点给予桩身足够的配筋量。与轴力相应，在基坑开挖后，桩侧表面即存在较大的摩阻力；若忽略该部分摩阻力的存在，将导致对上拔荷载作用下桩侧摩阻力估计的较大偏差。承受上拔荷载后，扩底桩桩端阻力承担了37%左右各级荷载的增量，体现了扩底端在抗拔荷载作用下的有效性。

关键词: 扩底桩, 抗拔, 深基坑开挖, 数值模拟

Abstract: The uplift resistance of the underreamed drilled shafts is numerical evaluated in this paper. The results indicate that a large uplift is induced due to the rebound of the excavated area. The neutral point is near the bottom of the enlarge area. Under the excavation condition, the actual axial uplift load is far larger than the unexcavated condition, and the maximum uplift load is not at the top of the drilled shaft where the load is imposed. It is suggested that enough reinforcement is necessary to prevent the excessive tension in the shaft. The shaft resistance induced by excavation is large and cant be ignored. The enlarged bottom is taking about 37% uplift loading. The numerical studies verify the effectiveness of underreamed drilled shaft for the uplift resistance.

Key words: Underreamed Drilled Shafts, Uplift Loading, Deep Excavation, Numerical Simulation