桩基础双折减系数有限元强度折减法极限分析

›› 2011, Vol. 32 ›› Issue (10): 3148-3154.

桩基础双折减系数有限元强度折减法极限分析

董天文^{1, 2}，郑颖人¹

1.后勤工程学院建筑工程系，重庆 400041；2.辽宁省交通高等专科学校道桥系，沈阳 110122

收稿日期:2011-03-01 出版日期:2011-10-10 发布日期:2011-10-13
作者简介:董天文，男，1970年生，博士（博士后），教授，主要从事岩土工程研究
基金资助:
辽宁省自然科学基金项目资助（No.20102103）

Strength reduction of limit analysis finite element method for pile foundation by two reduction-factors

DONG Tian-wen^{1, 2}, ZHENG Ying-ren¹

1. Department of Civil Engineering, Logistical Engineering University, Chongqing 400041, China; 2. Department of Road and Bridge, Liaoning Provincial College of Communications, Shenyang 110122, China

Received:2011-03-01 Online:2011-10-10 Published:2011-10-13

摘要/Abstract

摘要： 现行桩基础安全系数是对桩-土系统安全的总体性评价，尚不能明确桩侧剪移摩阻力、桩端阻力的发挥程度，模糊了基桩的力学特性。为此，基于不同的端阻力、桩侧阻力的发生机制以及占总承载力的比例不同，建立了桩端、桩侧地基两种安全储备系数（、），通过强度折减法非线性有限元极限分析实现了客观评价桩端、桩侧阻力的安全性问题。建议了桩端安全储备系数—位移曲线（ - 曲线）和桩侧安全储备系数—位移曲线（ - 曲线）的拐点、桩端安全储备系数—桩端阻力曲线（ - ）和桩侧安全储备系数—桩侧阻力曲线（ - 曲线）的拐点V型尖点的前一折减系数分别为当前桩顶荷载条件下基桩的桩端阻力安全储备系数和桩侧阻力安全储备系数。分析表明，地基材料的强度参数（c、）接近于实际情况时，双折减系数强度折减法计算结果接近于静载荷试验、荷载增量法和单折减系数法的计算结果，且 - 曲线拐点、 - 曲线拐点、 - 曲线V型尖点、 - 曲线V型尖点等物理意义较明确，计算的桩-土系统安全储备系数F接近于单一折减系数法确定的安全储备系数，双安全储备系数、具有一定实用性。

关键词: 桩基础, 有限元, 极限分析, 强度折减法, 极限荷载, 双折减系数

Abstract: The present safety factor of pile foundation judges the safe characteristic of pile-soil system integrally; but the mechanical character of pile is not clear for the end resistance and side friction of pile by using this safety factor. So, based on the bearing mechanism of end resistance and side friction of pile, and different proportion of two resistances to the total bearing capacity, the safety reserve factor of end resistance ( ) and the safety reserve factor of side friction ( ) are put forward; these two different safety reserve factors (SRFs) are objectively judged by strength reduction of nonlinear limit analysis FEM. The inflection points of - curve and - curve, and the previous reduction-factors on the sharp point of V type of - curve and - curve are estimated as the safety reserve factor of end resistance and the safety reserve factor of side friction under the load condition. The analysis of FEM shows that the results of two reduction-factors method are near to the results of static load tests, the load increment method and a safe reserve factor method when the strength parameters of ground (c and ) near to real parameters; and these inflection points of - curve and - curve, and the sharp point of V type of - curve and - curve have the specific physic purport; and the safety reserve factors of pile-soil system (F) by two reduction-factors method are close to the safety reserve factors of single reduction-factors method; and double safety reserve factors of and have some practicality in practice engineering.

Key words: pile foundation, finite elements, limit analysis, strength reduction method, ultimate load, two reduction-factors

中图分类号:

TU 473.1

董天文郑颖人. 桩基础双折减系数有限元强度折减法极限分析[J]. , 2011, 32(10): 3148-3154.

DONG Tian-wen ZHENG Ying-ren. Strength reduction of limit analysis finite element method for pile foundation by two reduction-factors[J]. , 2011, 32(10): 3148-3154.

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