超长桩荷载传递性状研究

根据超长桩的现场静载荷试验资料，分析了超长桩的单桩荷载传递特性。结果表明，超长桩表现出端承摩擦桩的特性，桩顶以下l/3桩长及桩端以上l/6范围内的桩侧摩阻力极限值接近规范推荐值，而中间部分的桩侧摩阻力远远大于规范值，表现出强化效应，桩端注浆桩的侧摩阻力强化效应更加明显。根据其荷载传递特性，提出了单桩极限承载力的估算公式，实例计算结果和实测结果较吻合。

Load transfer performance of overlength piles

This paper presents the test data of field static loading tests of overlength friction piles. The analysis of the data shows that the load transfer performance of overlength piles is similar to that of end-bearing friction piles. The ultimate side soil resistance from the depth of l/3 pile length beneath the ground surface to l/6 pile length is much higher than those recommended by the Specifications, which indicates that the side resistance is strengthened. However, the ultimate side resistance of other parts is in accordance with Specifications. And the base grouting can not only improve the soil bearing capacity under the piles, but also enhance in side soil resistance. Based on the analysis of the performance of overlength pile, a simplified method to calculate the ultimate load bearing capacity of single pile is suggested, which is validated by some pile case.