不同渗流条件下单桩的极限抗拔承载力分析

Analysis of ultimate uplift capacity of single pileunder different seepage conditions

为了了解不同渗流条件对抗拔桩的极限抗拔承载力的影响,研究抗拔桩在不同水头差条件下的作用机理。通过有限元分析研究单桩在不同渗流条件和竖向荷载作用下,孔隙水压力、有效应力及桩顶上拔荷载-上拔量关系曲线,揭示桩周土体有效应力、桩身轴力和桩侧摩阻力受渗流作用的影响,以及对抗拔桩的极限承载力的影响。结果表明,不同渗流条件对抗拔桩的极限承载力有显著的影响,土体向上渗流,土体有效应力随着渗流作用的增加而减小,会降低抗拔桩的极限承载力;反之向下渗流,土体有效应力随着渗流作用的增加而增大,会提高抗拔桩的极限承载力。

In order to study the influence of different seepage conditions of water head differences on the ultimate uplift capacity of uplift piles,the action mechanism of uplift piles was revealed under different seepage conditions of water head differences,providing guidance for the design of uplift piles in practical projects.Through the finite element analysis,the curves of single pile were studied on relationships between the uplift amount and the pore water pressure,the effective stress and the uplift load of pile top under different seepage conditions and vertical loads,demonstrating the influence of seepage on the effective stress of soil around pile,the axial force of pile body and the friction resistance of pile side,as well as its influence on the ultimate bearing capacity of uplift pile.The results show that,under different seepage conditions,the ultimate bearing capacity of uplift pile is significantly affected.In case of upward seepage of soil,the effective stress of soil decreases with the increase of seepage,reducing the ultimate bearing capacity of uplift pile;in case of downward seepage,the effective stress of soil increases with the increase of seepage,improving the ultimate bearing capacity of uplift pile.