预应力混凝土管桩轴心受压承载力计算

Bearing Capacity Calculation for the Prestressed Concrete Pipe Pile under Axial Compression

目的为准确考虑预应力钢筋产生的混凝土剩余预压应力的影响,提出预应力混凝土管桩轴心受压承载力计算公式,为编制黑龙江地区桩基础技术规范提供依据.方法考虑成桩工艺系数和预应力钢筋产生的混凝土剩余预压应力的影响,根据混凝土正截面承载力计算的基本假定中应力-应变的关系以及力的平衡和变形协调原则,推导预应力混凝土管桩正截面轴心受压承载力计算公式,并与国标图集《预应力混凝土管桩》（10G 409）进行对比分析.结果采用预应力混凝土管桩轴心受压承载力公式计算时,成桩工艺系数取0.85,对PHC桩和PC桩,混凝土剩余预压应力系数取值分别为0.56和0.60,对于常用的A型和AB型PHC桩,其承载力比采用国标图集《预应力混凝土管桩》（10G 409）的提高8%～12%.结论采用推荐公式和设计建议计算的管桩轴心受压承载力与国标图集《预应力混凝土管桩》（10G 409）相比具有一定的提高,为预应力混凝土管桩在黑龙江地区合理的推广应用提供技术支持.

In order to consider the influence of concrete residual prepressing stress produced by prestressed reinforcement,a calculation formula for bearing capacity of the prestressed concrete pipe pile under axial compression was proposed,which can provide references for compiling the technical code of pile foundation in the Heilongjiang area. Considering influences of the pile construction process coefficient and the concrete residual preloading stress caused by prestressed reinforcement,according to the stress-strain relationship in the basic assumption for calculating normal section bearing capacity of concrete and the principle of force balance and deformation compatibility,a formula for calculating bearing capacity of prestressed concrete pipe pile under normal section axialcompression was derived. Calculated results were compared with the national standard ＂Prestressed concrete pipe ＂（ 10 G 409）. Results show that when the pile construction process coefficient is0. 85,the concrete residual preloading stress coefficient is 0. 56 and 0. 60 for PHC pile and PC pile,respectively,for the commonly used type A and type AB,the bearing capacities calculated by the proposed formula are raised by 8% ～ 12%,compared with the national standard ＂Prestressed concrete pipe＂（ 10 G 409）. Conclusion is that the calculated bearing capacity for the prestressed concrete pipe pile under axial compression has a certain increase compared with the national standard ＂Prestressed concrete pipe＂（ 10 G 409）. The obtained formula can provide technical supports for reasonable popularization and application of the prestressed concrete pipe pile in the Heilongjiang area.