考虑上拔力作用点位置影响的抗拔桩变形分析

上拔力作用点位置对抗拔桩摩阻力分布有决定性影响,是分析抗拔桩荷载变形机理的关键性因素。根据试验资料,将抗拔桩离散成作用点以上的上部承压桩和作用点以下的下部抗拔桩,两者在上拔力作用点所在截面满足荷载平衡条件和位移协调条件,由此可建立反映上拔力作用点位置影响的抗拔桩分析模型,该模型采用荷载传递法求解,得出了不同上拔力作用点下摩阻力分布、桩顶荷载位移、作用点所在截面荷载位移解析解。理论解表明,上拔力作用点以上和以下的桩体都存在临界桩长现象。文章还提出了最优上拔力作用点概念及其计算方法,对实际工程具有重要的指导意义。

DEFORMATION ANALYSIS FOR UPLIFT PILES CONSIDERING THE ACTION POSITION OF UPLIFT FORCE

The action point of uplift force plays a dominant role in the distribution of friction resistance along uplift piles,and thus it is a key factor in the analysis of the loaddisplacement relationship of uplift piles.The analysis model of uplift pile is established by dividing the pile shaft into two parts according to experimental data.The pile portion above the dividing action point is considered as a compressive pile,the portion under the action point is considered as a tension pile,and these two pile portions satisfy equilibrium and compatibility equations.The model is solved by using a load transfer method,and analytical solutions of friction resistance force distribution and loaddisplacement relationship are obtained.Analytical solutions indicate that criticallength phenomenon exists for both pile portions.The action position of uplift force can be optimized,and the corresponding calculation method is proposed.