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讨论了桩间距对矩形桩基承台冲切承载力的影响,并运用上限解法和下限解法进行分析。结果表明:当承台尺寸满足一定条件时,冲切承载力随桩间距的增大而下降;规范计算中冲切承载力仅包含斜截面混凝土剪压区剪力,计算公式可以利用承台冲切名义剪应力的概念理解,冲切承载力下降是由于斜截面由剪压破坏向斜拉破坏发展;基于承台冲切破坏空间桁架理论,冲切承载力下降是由于位于冲切锥体内部的斜压杆承担的荷载比例增加,使得斜裂缝上下端的剪压区更容易破坏。
The effect of pile spacing on the punching bearing capacity of rectangular pile foundations was discussed. The upper bound solution and lower bound solution were analyzed. The results show that when the size of the cap reaches a certain condition, the punching shear capacity decreases with the increase of the pile spacing. The punching load capacity of the standard calculation only includes the shear force of the concrete shear zone in the diagonal section. According to the notion of nominal shear stress, the decrease of punching load capacity is due to the oblique cross-section descending from the shear failure to the tensile failure. Based on the truss theory of the punching failure of the platform, the reduction of punching load capacity is due to the fact that the punching shear cone Of the ramp load bearing rod to increase the proportion of the upper and lower oblique shear zone so that the shear zone more easily damaged.