为了对基坑下的抗拔桩原位试验结果的准确度进行探究，以南昌艾溪湖公轨共建隧道工程为背景，采用模型试验的方法，通过改变基坑开挖范围，研究了在开挖卸荷条件下抗拔桩的应力响应以及变形规律，继而揭示抗拔桩承载机理。结果表明：当桩长一定时，增加基坑深度会大幅度的降低桩基承载力，增大桩顶荷载-位移曲线斜率；当基坑宽度大于“边界效应”临界值时，基坑宽度的增加对抗拔桩承载特性影响较小；在极限荷载作用下，桩的法向应力沿桩长近似直线分布。当基坑深度H = 0.2 ~ 0.6 m时，荷载-位移曲线斜率约为未开挖状态下的3.25 ~ 1.4倍。

In order to explore the accuracy of the in-situ test results of the uplift piles under the foundation pit, the stress response and deformation law of the uplift piles under the excavation and unloading conditions were studied by changing the excavation range of the foundation pit by using the model test method, and then the bearing mechanism of the uplift piles was revealed. The results show that when the pile length is constant, increasing the depth of the foundation pit will greatly reduce the bearing capacity of the pile foundation and increase the slope of the load-displacement curve at the top of the pile. When the width of the foundation pit is greater than the critical value of "boundary effect", the increase of the width of the foundation pit has little effect on the bearing characteristics of the uprooted pile. Under the ultimate load, the normal stress of the pile is distributed in an approximately straight line along the length of the pile. When the depth of the foundation pit H value between 0.2 m to 0.6 m, the slope of the load-displacement curve is about 3.25 ~ 1.4 times of the unexcavated state.