超大直径扩底嵌岩桩模型试验研究

Study on model test of super large diameter rock socketed pile with belled shaft

为了弥补因现有技术无法对深圳平安大厦进行现场试桩分析的不足,研究超大直径桩的桩身承载及沉降规律,采用缩尺模型试验的方法对其进行了研究。研究结果表明:超大直径嵌岩桩桩身最大承载力远高于规范计算得到的竖向抗压承载力特征值,其上部荷载主要由桩端承担,对桩进行扩底处理后桩端承载所占总荷载比例较等直径桩更大,且等直径嵌岩桩的侧摩阻力比扩底嵌岩桩的侧摩阻力的发挥更显著。桩身在中风化—微风化花岗岩段的侧摩阻力在设计中均不应忽略。现场实测结果对比验证了模型试验结果的合理性。

To make up the shortage that the field pile test analysis can’t be conducted on Shenzhen Pingan Financial Center based on the current technologies,the load-bearing and settlement characteristics of the super large diameter pile were studied by using the method of reduced scale model test. The results showed that the maximum bearing capacity of super large diameter rock socketed pile was much higher than the characteristic value of vertical compressive bearing capacity calculated by the code. The upper load was mainly born by the pile end,and the proportion of load-bearing by the pile end in the total load-bearing after the belled shaft treatment on the pile was larger than that of equal-diameter pile. The side friction of equaldiameter rock socketed pile played more obvious than that of rock socketed pile with belled shaft. The side friction of piles in the moderately weathered granite to slightly weathered granite sections should not be ignored in the design. The field measurement results comparatively verified the rationality of the model test results.