钢护筒对超长钻孔灌注桩承载性能的影响

The influence of steel casing on behavior of over-long drilled pile

苏通大桥主塔墩采用群桩基础,由131根长度为117m的超长钻孔灌注桩组成。为了提高群桩基础的侧向刚度,采用了保留钢护筒的设计。为研究钢护筒对钻孔灌注桩承载性能的影响,利用实测数据分析了含钢护筒的钻孔灌注桩的传力机理,同时用有限元法结合试验数据研究了钢护筒对桩基础承载性能的影响。结果表明,对于单桩而言,钢护筒可以提高其承载性能,传力机理有别于一般超长桩,上部荷载由基础和钢护筒共同承担;对于群桩而言,钢护筒可以使荷载分布更均匀。

The foundation kind of Sutong Bridge is pile-group foundation. It is composed of 131 over-long piles which are llTm long. In order to improve the lateral stiffness of the pile group foundation, the steel casing was left. In order to study the influence of steel casing on behavior of over-long drilled pile, the bearing behavior of drilled pile with steel casing was analyzed by monitoring data, and the influence of steel casing on bearing behavior of pile-group foundation was also studied by finite element method. The result shows that steel casing can improve the bearing behavior of a single pile, and its load transfer mechanism is different from the piles in common. For the pile group foundation with steel casing, the load distribution is more even.