由于忽略了基坑卸荷效应对抗拔桩承载性状的影响，故当开挖卸荷面积较大时，原位试桩结果的准确性尚待考究，且目前关于抗拔桩研究多以桩侧摩阻力反映桩的承载性状，对于桩侧桩-土界面法向压力研究较少。桩侧桩-土界面法向压力与桩侧摩阻力相较而言，可以直观地体现基坑开挖卸荷对抗拔桩承载性状影响。有鉴于此，采用模型试验与数值模拟相结合的方法，通过改变基坑开挖范围和桩粗糙度等变量，探究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：基坑开挖的卸荷效应与基坑深度、宽度、有效桩长和桩侧粗糙度有关，按影响程度分：有效桩长>基坑深度>桩侧粗糙度>基坑宽度；基坑宽度对桩抗拔承载特性的影响存在临界值，当基坑宽度大于临界值时，基坑宽度的增加对抗拔桩承载特性影响较小；在同一有效桩长条件下，开挖后的桩侧法向应力与基坑深度成正比，与基坑宽度成反比，与桩粗糙度的关系较小；在同一有效桩长条件下，开挖后的桩侧摩阻力与基坑深度、桩的粗糙度成正比，与基坑宽度成反比。

Due to ignoring the influence of foundation pit unloading effect on the bearing properties of uprooted piles, the accuracy of in-situ test results needs to be studied when the excavation unloading area is large, and the current research on uplift piles mostly reflects the bearing properties of piles based on pile side friction resistance, and there are few studies on the normal pressure of pile-soil interface on pile sides. Compared with the frictional resistance of the pile side, the normal pressure of the pile-soil interface on the pile side can intuitively reflect the influence of foundation pit excavation and unloading on the bearing properties of the uprooted pile. In view of this, the combination of model test and numerical simulation was used to explore the stress response and deformation law of uplift piles under excavation and unloading conditions by changing the variables such as foundation pit excavation range and pile roughness, and then the bearing mechanism of uplift piles was revealed. The results show that the unloading effect of foundation pit excavation is related to the depth and width of the foundation pit, the effective pile length and the pile side roughness, according to the degree of influence: the effective pile length > the depth of the foundation pit > the roughness of the pile side > the width of the foundation pit. When the width of the foundation pit is greater than the critical value, the increase of the width of the foundation pit has little effect on the bearing characteristics of the uplift pile. Under the condition of the same effective pile length, the normal stress of the excavated pile side is proportional to the depth of the foundation pit and inversely proportional to the width of the foundation pit, and the relationship with the pile roughness is small. Under the condition of the same effective pile length, the frictional resistance of the pile after excavation is directly proportional to the depth of the foundation pit and the roughness of the pile, and inversely proportional to the width of the foundation pit.