高临界循环荷载水平下钻孔桩的抗拔性状分析

为了研究抗拔桩在循环加载过程中桩身的性状，选取杭州萧山某工地两根抗拔桩作为试桩进行循环加载试验。在抗拔桩桩身埋设钢筋应力计，测量循环加载过程中桩身应力的变化情况；在桩身预埋钢管，测量桩顶及桩端上拔量。通过对桩身应力及桩顶、桩端上拔量的分析，研究循环加载对抗拔桩承载力及上拔量的影响。综合分析抗拔桩承受循环荷载时的桩顶、桩端上拔量、桩身轴力以及桩侧摩阻力分布可知，当抗拔桩承受循环荷载时，且临界循环荷载水平较大（接近或者达到1），抗拔桩经过2～3次循环加载后就发生破坏，其研究结果可供其他类似工程参考。

Uplift behaviors of bored piles subjected to high critical cyclic loading level

In order to study the behaviors of uplift pile subject to cyclic load,cyclic loading tests are carried out on two uplift piles at Xiaoshan,Hangzhou.Stress gauges and steel pipes are pre-buried in the test pile to measure the changes of pile shaft stress and the pull-out amount of both pile tip and pile head.Through the analysis of the pile shaft stress and the pull-out amount,the influence of cyclic load on bearing capacity and pull-out amount are studied.Comprehensive analysis of the pull-out amount,pile shaft force and pile side friction,it is drawn a conclusion that the uplift pile damaged after two or three cycles when uplift pile subjects to cyclic load,and the critical cyclic load level is close to 1.