钢管埋深对钢管混凝土复合桩竖向承载特性的影响

Influence of pipe bury depth on vertical bearing characteristics of concrete filled steel tubular composite pile

作为水域中桩基础施工的围堰结构,钢护筒的应用愈加广泛,钢护筒因为施工或者拆除困难等原因有时不再回收,从而与钢筋混凝土材料一起形成钢管混凝土复合桩。为探明钢管埋深对钢管混凝土复合桩竖向承载特性的影响,通过离心模型试验,着重研究钢管埋深对钢管混凝土复合桩桩侧摩阻力、桩端阻力等因素的影响。结果表明:钢管混凝土复合桩的上部钢管段(钢护筒)合理埋深为桩长的1/3,当钢管段埋深小于1/3桩长时,钢管混凝土复合桩的桩侧摩阻力会出现双峰现象,当钢管段埋深大于1/3桩长时,钢管混凝土复合桩的桩侧摩阻力双峰现象将逐渐消失;根据钢管混凝土复合桩的竖向承载特性,提出适用于钢管混凝土复合桩的竖向极限承载力计算公式,以期为钢管混凝土复合桩的设计与施工提供理论指导。

As a cofferdam structure in the construction of pile foundations in water,the application of steel casing is more and more widespread.Because of the difficulties in construction or demolition,the steel casing is sometimes no longer recycled,thus forming a concrete filled steel tubular composite pile with reinforced concrete materials.In order to find out the influence of pipe bury depth on the vertical bearing characteristics of concrete filled steel tubular composite pile,this paper emphatically studies the influence of pipe bury depth on the side friction resistance and pile end resistance.The results show that the upper steel pipe section(steel casing)is reasonably buried in the 1/3 of the pile length,and when the buried depth of steel pipe section is less than 1/3 pile length,double peak phenomenon will appear in the side friction resistance,when the buried depth of steel pipe section is greater than 1/3 pile length,the double peak phenomenon will gradually disappear.According to the vertical bearing characteristics of concrete filled steel tubular composite pile,the formula for calculating the vertical ultimate bearing capacity of concrete filled steel tubular composite pile is put forward,which will provide theoretical guidance for the design and construction of concrete filled steel tubular composite pile.