大直径预应力高强混凝土管桩抗剪承载力数值模拟研究

Numerical Simulation Research on Shear Capacity of PHC Pipe Pile with Large Diameter

针对预应力高强混凝土(PHC)管桩抗剪承载力的问题,现有规范和图集提出了不同的计算公式。为了探究大直径PHC管桩的极限抗剪承载力,在现行公式计算结果与前人试验结果的基础上,采用ABAQUS数值模拟软件,对工程中常用的大直径(600~1000 mm)PHC管桩的抗剪承载力进行数值分析。通过分析剪跨比为1.5~3.0的管桩在剪压破坏过程中破坏面混凝土和箍筋的抗剪承载力,得出以下主要结论:管桩抗剪承载力在下降过程中表现出波动下降的趋势;管桩达到最大抗剪承载力与管桩破坏不同步,在达到最大抗剪承载力时,管桩中性轴上部混凝土发生拉裂;随着位移加载的进行,在拉裂缝基本贯通时,桩身混凝土发生破坏,箍筋应力增大,且箍筋屈服,但未断裂。最后,在现有公式的基础上,基于45°破裂面假设,提出了PHC管桩抗剪承载力计算公式。

On the question of the shear capacity of PHC pipe pile,different calculations were proposed in the current specifications and collective drawings.In order to explore the ultimate shear capacity of PHC pipe pile with large diameters,ABAQUS numerical simulation software was used to analyze the shear capacity of PHC pipe pile which was commonly used in engineering and has large diameters(600~1000 mm),on the basis of the calculation results of the current specifications and the results of previous experiments.By analyzing the shear capacity of concrete and stirrup on the failure surface with shear span ratio of 1.5~3.0 and during shear compression failure,the major conclusions were as follows:the shear capacity of pipe pile showed a fluctuating decline during the decline process;the pipe pile’s maximum shear capacity was not synchronized with the failure of the pipe pile;when the maximum shear capacity is reached,the tensile cracks had occurred in the concrete upper neutral axis of the pipe pile.With the progress of displacement loading,when the tensile cracks were basically penetrated,the pile concrete had destroyed,the stirrup stress had increased,and the stirrup had yielded but the stirrup did not break.Finally,a formula for the shear capacity of PHC pipe pile was proposed on the basis of the current formula and the 45°fracture surface assumption.