In recent years, the usage of large-diameter plain-concrete pile composite foundations has undergone rapid growth in China, especially for high-rise buildings. In this paper, the mechanical characteristics of large-diameter plain-concrete piles are studied by in situ monitoring and a finite element simulation. The results show that the axial force, the soil pressure, and the pile-soil stress ratio all increase simultaneously with increasing applied loads. The axial force initially increases along the pile length and then decreases. The distribution of the side friction along the pile body shows a three-segment broken-line pattern, and the positions of the maximum positive and negative friction resistance remain unchanged as the applied loads increase. Based on the pile-soil deformation compatibility derived from the in situ monitoring data and finite-element method simulation, a simplified calculation method to analyze the pile-soil interaction is proposed. Moreover, a comparison between the proposed calculation method and a finite-element simulation is given, and the result shows that the data obtained by both approaches agree well.

近年来，大直径素混凝土桩复合地基的使用在我国快速增长，特别是在高层建筑中。本文通过现场监测和有限元模拟研究了大直径素混凝土桩的力学特性。结果表明，轴向力、土压力和桩土应力比都随着施加载荷的增加而同时增加。轴向力最初沿桩长增加，然后减小。桩身侧摩擦力分布呈三段折线状，最大正负摩擦阻力位置随外加载荷的增加而保持不变。基于现场监测数据得到的桩土变形相容性和有限元法模拟，提出了一种桩土相互作用的简化计算方法。此外，给出了所提出的计算方法与有限元模拟之间的比较，结果表明两种方法获得的数据吻合良好。