宽浅式筒型基础竖向承载力研究

通过有限元计算,研究了不同长径比下筒型基础竖向压载作用下的承载特性,分析了竖向荷载作用下宽浅式筒型基础的失效模式,并与试验结果进行对照,数值计算与模型试验的荷载–位移曲线虽存在一定差距,但整体趋势相近。对筒型基础不同部位在承担竖向压载时所承担的比例变化进行分析,其中,筒顶接触反力、内侧摩阻力及端阻力承担90%以上的荷载比例,计算极限承载力时可将筒内土与筒作为一个整体。给出了筒壁土压力的分布形式,在汉森理论的基础上提出适用于宽浅式筒型基础竖向承载力的计算公式,并与有限元、试验结果进行比较,除长径比为1.0的模型外,相对误差均在10%以内。

Vertical bearing capacity of wide-shallow bucket foundation

The criteria of vertical bearing capacity and the failure mode of a wide-shallow bucket foundation are analyzed by using model tests, finite element and theoretical methods. The finite element method (FEM) is used to study the bearing characteristics of the bucket foundation with different aspect ratios (L/D) and to analyze the failure mode of the wide-shallow bucket foundation under vertical load. The FE results are compared with those from the model tests. The load-displacement curves from numerical calculations have certain deviation compared with those from the model tests, but their overall trend is similar. The variation of loading ratio in different parts of the bucket foundation shows that the contact reaction-force of head cover, inner frictional resistance and end resistance share more than 90% of the total vertical load, so the bucket foundation and the soil inside the bucket foundation can be considered as an integrality to calculate the vertical bearing capacity. The distribution of earth pressure is given. The computational formula for the vertical bearing capacity is put forward based on the Hanson theory. The results are compared with those from FEM and model tests, and the relative error is less than 10% except that L/D=1.0. The computational formula is more suitable to the wide-shallow bucket foundation.