基于极限承载力试验的扩底抗拔桩承载特性数值模拟分析

发布时间：2018-04-30 01:38

本文选题：扩底桩 + 抗拔桩　；参考：《岩土力学》2015年S1期

【摘要】：基于天津于家堡南地下车库工程扩底桩抗拔极限承载力试验,结合数值模拟手段对扩底桩抗拔承载特性、破坏模式和受力机制开展了分析研究。计算分析表明,扩底桩(有效桩长19 m)相比等截面桩抗拔极限承载力提高约50%,材料增加仅8.5%,扩底桩扩大头周边土体提供的抗力显著提高了抗拔承载力;荷载较小时抗拔力主要由等截面段侧摩阻力提供,扩头段抗拔力占桩顶加载的比值随加载近似呈线性增加;扩底桩等截面段沿桩土界面先发生剪切破坏,扩头段周边土体后发生受压破坏,抗拔承载力达到极限;扩头段位于同一土层时,不同桩长扩头段提供的极限抗拔力相差不大,桩长越长,扩头段抗拔力贡献率越低;扩头段抗拔力主要由自重、扩头段法向力竖向分力和侧摩阻力组成,其中法向力竖向分量提供了扩头段的主要抗拔力,占扩头段总抗拔力约70%。
[Abstract]:Based on the ultimate uplift bearing capacity test of bottom pile in Tianjin Yujiabongnan Underground Garage Project, combined with numerical simulation, the characteristics of uplift bearing capacity, failure mode and stress mechanism of bottom enlarged pile are analyzed and studied. The results of calculation and analysis show that the ultimate bearing capacity of pedestal pile (effective pile length 19 m) is about 50% higher than that of equal section pile, and the increase of material is only 8.5%. The resistance of the soil around the enlarged head of the enlarged bottom pile improves the uplift bearing capacity significantly. When the load is small, the pullout force is mainly provided by the lateral friction of the equal section, the ratio of the pull-out force to the top of the pile increases linearly with the loading, and the shearing failure occurs along the interface between the pile and the soil at the same section of the reamed pile. When the extension head section is located in the same soil layer, the difference of the ultimate uplift resistance of the different pile extension head section is not significant, the longer the pile length, the lower the pull-resistance contribution rate of the expanding head section. The pullout resistance of the expanding head is mainly composed of self-weight, vertical component of normal force and lateral friction resistance, in which the vertical component of the normal force provides the main pull-out resistance of the expanding head, which accounts for about 70% of the total pull-out resistance of the expanding head.
【作者单位】：华东建筑设计研究总院地基基础与地下工程设计研究中心;
【基金】：国家科技支撑计划课题(No.2012BAJ01B02)
【分类号】：TU473.1

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