基坑开挖对抗拔桩承载特性影响的数值分析  

Numerical analysis of bearing behaviors of uplift piles during pit excavation

作　　者：林敏博 刘润[1] 徐余[2] 李然[1] 

机构地区：[1]天津大学水利工程仿真与安全国家重点实验室,天津300072 [2]天津市建筑设计院,天津300074

出　　处：《岩土工程学报》2013年第S2期735-739,共5页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金创新研究群体科学基金项目(51021004);天津市自然科学基金面上项目(12JCYBJC14700)

摘　　要：基坑开挖导致地基土体整体处于卸荷状态,从而改变了抗拔桩原有的受力特点。采用数值分析方法,系统研究了基坑开挖导致的原地基中抗拔桩承载特性改变,从基坑开挖的范围、桩的相对位置等方面探讨了对桩的极限抗拔承载力、桩侧摩阻力、桩身轴力的影响规律。结果表明,开挖导致坑底以下土体卸荷回弹,在桩身上部产生正摩阻力,下部产生负摩阻力,桩身产生轴向拉力,极限抗拔力降低,减低程度与基坑开挖的规模成比例;基坑开挖所导致的群桩桩侧摩阻力与桩身轴力变化程度依次为:中心桩>边桩>角桩;群桩的遮帘作用在很大程度上影响中心桩极限抗拔承载力。The excavation results in unloading state of the soils, which influences the original loading characteristics of uplift piles. Based on the numerical simulation method, change of the bearing behaviors of the uplift piles caused by excavation is systematically studied. The rules of ultimate uplift capacity, side friction and axial force are discussed by comparing different excavation scopes and relative locations. The results show that, excavation leads to soil rebound under the bottom, induces positive side friction in the upper part of the piles and negative side friction in the under part, and reduces the ultimate uplift capacity of the piles. Moreover, the degree of decrease is proportional to the size of the foundation excavation. The variation of side friction and axial force of the center pile caused by foundation pit excavation is more obvious than that of side pile and corner pile and change of corner pile is the minimum. The ultimate uplift capacity of the center pile is largely affected by the curtain effect of group piles.

关 键 词：抗拔桩 基坑开挖 侧摩阻力 极限抗拔力 

分 类 号：TU473.11[建筑科学—结构工程]