某高层建筑大直径嵌岩钻孔灌注桩的承载力分析

大直径嵌岩钻孔灌注桩已被越来越多的高层建筑所采用。如何根据没有达到极限荷载的试桩资料确定单桩轴向承载力是一个很现实的问题。本文通过分析软岩中两根大直径嵌岩钻灌注桩的荷载——沉降曲线(未达到极限荷载),利用斜率倒数法和导数图法分别推算了单桩承载力,并与采用JGJ4-80规范中公式的计算结果进行了对比,吻合较好。最后简单讨论了这种类型桩的承载机理、桩侧阻力和桩端阻力的分配比例,本文认为,对于桩侧和桩端阻力应当采用不同的安全系数。

THE BEARING CAPACITY ANALYSIS ABOUT LARGE BORED PILES INLAID IN ROCKS OF A TALL BUILDING

Large bored piles inlaid in rocks have been more used in tall buildings. How to determine axial bearing capacity of single pile, according to data of pile load test researched the ultimate load, is a very actual problem. By analyzing the load-settlement curves of two large bored piles inlaid in soft rocks, making use of the inverse slope method and derivative graph method, we predicted the bearing capacities of these two piles. When it was compared with the calculating result using the formula of Chinese JGJ4-80 Standard, they accorded well.At last, this paper simply discussed the bearing mechanism of this kind of piles, and the distributing proportion of pile surface resistance to pile tip resistance. As for pile surface and tip resistance, we think that diffrent safety factors should be adopted.