倾斜上拔荷载下挤扩支盘桩响应分析

Response of squeezed branch piles under inclined uplift loads

为研究挤扩支盘桩在倾斜上拔荷载下的响应,利用ABAQUS对该受荷模式下挤扩支盘单桩进行了数值模拟,得到了5种上拔和水平荷载组合下两盘和三盘挤扩支盘桩盘数在不同盘间距下的荷载-位移曲线及桩身内力和位移的分布规律。数值结果表明:单桩在上拔和水平荷载作用下存在荷载耦合,上拔荷载明显减小了单桩水平刚度,水平荷载减小了单桩竖向刚度,但影响有限;基于数值结果提出复合承载力计算的椭圆公式,本文的对比结果表明:该公式的预测误差小于10%,且预测结果偏于安全;水平荷载的存在导致靠近土体表面首盘的抗拔能力不能充分发挥;建议在水平与上拔荷载比较大的支盘桩中,首盘到土面距离不宜小于8d。

The commercial software ABAQUS is employed to analyze the response of squeezed branch piles under inclined uplift loads.A two-plate and three three-plate squeezed branch piles are modeled in current analysis.Results obtained include the combined load-displacement curves,the internal forces and the displacement distributions along the piles.It is found that there is a coupling between the uplift and lateral loads,that is,the uplift loading significantly decreases the lateral stiffness of a pile,while the lateral loading slightly decreases the uplift stiffness of the pile.An elliptical equation is proposed to predict the combined ultimate capacity of squeezed branch piles.The comparison between the predicted results based on the elliptical equations and the numerical results shows that the accuracy of the equation is within 10% and the predicted values are lower.In addition,effects of plates on the distributions of axial force,bending moment and lateral displacement are also discussed.