黏土中超长群桩竖向承载力模型试验研究

针对超长群桩使用较多而理论研究较少的现状,进行了大型的室内超长群桩模型试验。通过对黏性土中桩距为6d的超长钻孔灌注群桩的室内模型试验和实测数据分析,研究了超长群桩的荷载传递机理和承载力特性。得到了在竖向荷载作用下超长群桩的荷载与沉降关系曲线,桩身压缩量占桩顶沉降的百分比、桩身轴力分布曲线以及桩侧摩阻力分布曲线。研究结果表明:超长群桩属于非刚性摩擦桩,桩顶沉降主要由桩身压缩量引起;极限荷载作用下,桩端阻力接近为零,桩身中下部的侧摩阻力没有充分发挥。这些结论为超长群桩的理论研究、工程设计与施工提供有益参考。

Model tests on vertical bearing capacity of super-long pile groups in clay

According to the current situation of super-long pile groups,i.e.more application and less theoretical studies,a large-scale laboratory model test is conducted.By the model test and data analysis of super-long bored pile group with 6d pile spacing in clay,the load transfer mechanism and bearing capacity behaviors are studied.The load-settlement curve,the proportion between pile compression and pile top settlement,the distribution of axial force and lateral frictional resistance under vertical loads are obtained.The results show that the basic piles in the super-long pile groups are non-rigid friction piles,and the pile top settlement is mainly induced by pile compression;under the ultimate load,the pile tip resistance is close to zero and the lateral frictional resistance in the middle-lower part is not fully utilized.These conclusions can provide a useful guidance for the theoretical researches,engineering design and construction of super-long pile groups.