开挖条件下非均质地基中单桩竖向承载特性非线性分析

doi:10.16285/j.rsm.2017.06.015

›› 2017, Vol. 38 ›› Issue (6): 1666-1674.doi: 10.16285/j.rsm.2017.06.015

开挖条件下非均质地基中单桩竖向承载特性非线性分析

纠永志^{1, 2, 3}，祝彦知¹

1. 中原工学院建筑工程学院，河南郑州 450007；2. 同济大学地下建筑与工程系，上海 200092； 3. 同济大学岩土及地下工程教育部重点实验室，上海 200092

收稿日期:2015-11-02 出版日期:2017-06-12 发布日期:2018-06-05
作者简介:纠永志，男，1982年生，讲师，从事岩土工程方面的科研和教学工作
基金资助:
国家自然科学基金项目（No.51608548）；河南省科技攻关项目（No.082102360056）；郑州市科技攻关计划项目（No.10PTGG382-2）。

Nonlinear analysis for bearing characteristics of vertically loaded single pile in non-homogeneous soil under excavation

JIU Yong-zhi^{1, 2, 3}, ZHU Yan-zhi¹

1. School of Civil Engineering and Architecture, Zhongyuan University of Technology, Zhengzhou, Henan 450007, China; 2. Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China; 3. Key Laboratory of Geotechnical and Underground Engineering of Ministy of Education, Tongji University, Shanghai 200092, China

Received:2015-11-02 Online:2017-06-12 Published:2018-06-05
Supported by:
This work was supported by the National Natural Science Foundation of China (51608548), the Science and Technology Project of Henan Province (082102360056) and the Science and Technology Project of Zhengzhou City (10PTGG382-2).

摘要/Abstract

摘要： 在考虑开挖引起土体回弹和土体强度特性、应力状态变化的基础上，提出了开挖条件下非均质地基中竖向受荷单桩非线性计算方法，并与已有试验结果对比，证明了简化方法的正确性，并对开挖前、后单桩的竖向承载特性的变化以及开挖后土体回弹对基桩受力和变形的影响进行研究分析。研究表明，常规试桩法和套管试桩法高估了基桩竖向极限承载力和桩顶刚度，采用常规试桩和套管试桩法得到的承载力作为设计值偏于不安全；开挖卸荷引起桩周土体回弹使得桩身出现拉力，开挖深度较大时桩身中、下部的配筋应充分考虑由于开挖引起的沿桩身的拉力，防止开挖过程中基桩被拉断；桩周土体的卸荷回弹将会引起桩顶刚度的明显降低。

关键词: 开挖, 极限承载力, 土体卸荷回弹, 桩顶刚度, 超固结

Abstract: In this study, a simplified nonlinear calculation method was developed to analyze the single pile in non-homogeneous soil under excavation, considering the unloading rebound of soil and changes of soil property caused by excavation. The calculated results show good agreement with testing results obtained by the present method, which indicates that the validity of this method is verified. Moreover, we studied the responses of the single pile after excavation under vertical load using the simplified method. It is found that the ultimate vertical bearing capacity and vertical stiffness of the pile loaded after excavation are overestimated by both the conventional loading test method and loading test with the sleeve method, which could lead to an unsafe design. In addition, excavation causes rebound of soils around the pile and then results in tension force in the pile. To avoid the pile be pulled apart, the reinforcing bars in the middle-lower part of the pile should be raised when the excavation depth is deep. The unloading rebound of soil around caused a great decrease in stiffness of the pile top.

Key words: excavation, ultimate bearing capacity, soil unloading rebound, pile top rigidity, over-consolidation ratio

中图分类号:

TU 443

纠永志，祝彦知，. 开挖条件下非均质地基中单桩竖向承载特性非线性分析[J]. , 2017, 38(6): 1666-1674.

JIU Yong-zhi, ZHU Yan-zhi，. Nonlinear analysis for bearing characteristics of vertically loaded single pile in non-homogeneous soil under excavation[J]. , 2017, 38(6): 1666-1674.

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开挖条件下非均质地基中单桩竖向承载特性非线性分析

Nonlinear analysis for bearing characteristics of vertically loaded single pile in non-homogeneous soil under excavation

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