基于模型试验方法，开展砂土中竖向荷载作用下低承台2×1和2×2扩底楔形桩群桩桩-土相互作用模型试验，测得不同荷载等级下桩顶荷载-沉降关系曲线、桩端阻力以及桩身轴力等分布规律，同时开展扩底楔形桩单桩竖向承载特性试验作为对比分析。结合JGJ94规范规定的承台效应系数和群桩效应系数，对扩底楔形桩群桩竖向极限承载力进行了理论计算分析。研究结果表明，文中试验条件下竖向荷载作用下低承台2×1和2×2扩底楔形桩群桩的综合效应系数分别为1.16和1.10；无承台作用下2×1和2×2扩底楔形桩群桩的群桩效应系数分别为0.95和0.88；理论计算中扩底楔形桩承台效应系数和群桩效应系数可以参照等直径桩的相关规范取值。

Based on model test method, pile-soil interaction characteristics of 2×1 and 2×2 belled wedge pile groups embedded in sand under vertical load are carried out. The load versus settlement of pile top, pile tip resistance and the axial force of pile distribution along depth are measured. Meanwhile, model test on vertical bearing capacity of single belled wedge pile are also carried out for comparative analysis. Considering the coefficient values of cap effect and group effect noted in JGJ94 code, the ultimate bearing capacities of belled wedge pile groups are calculated. In this model test conditions, the results show that the group effect coefficients of 2×1 and 2×2 belled wedge pile groups with low cap equal 1.16 and 1.10, respectively; and those of pile groups without cap equal 0.95 and 0.88, respectively. The values of cap effect and group effect coefficients for traditional equal section pile can be used for belled wedge pile.