劲性复合桩承载力计算方法探讨

Bearing Capacity Calculations of Strength Composite Piles

劲性复合桩是一种将水泥土搅拌桩成本低廉的优点与钢筋混凝土预制桩强度、刚度较大的优点结合起来的组合型桩体。这种桩体已有十多年的发展历史,有较丰富的工程实践,也有许多相应的设计规范。本文选取了四个有代表性的规范,结合江苏海安的一个工程实例,对这些规范中承载力的计算方法进行了研究探讨。计算结果表明,只有充分考虑了劲性复合桩的四种破坏模式和复合段桩土侧摩阻力的增大系数,才能得出符合实际、安全经济的计算结果。混凝土芯桩与水泥土桩之间有很强的粘结力,一般不会成为承载力的控制条件,但需要进一步的定量研究。本文在上述规范中的承载力计算方法的基础上,提出了改进的承载力计算公式,工程实例表明改进公式在粉土粉砂地层有较高的可靠性。

The strengthened composite piles are the composite piles,which combine the advantages of the cheap cement mixing columns and those of the strong and rigid precast reinforced concrete piles. The strengthened composite piles have been used in engineering practice for more than ten years. This paper selected four representative specifications and the bearing capacity calculation methods applied to a project in Hai'an,Jiangsu province. The results showed that it's necessary to consider the four failure modes of the strength composite piles and the increase of soil side skin friction at composite sections fully,in order to obtain realistic,safe and economic calculation results.There is enough cohesive force between the concrete pile and the mixing pile generally,but it needs further research.This paper improved the calculation formulas of bearing capacity of the strength composite piles in those specifications and verified the reliability of the improved formulas used in silt layers by the engineering practice in Hai'an.