《建筑桩基技术规范》中嵌岩桩下压承载力计算方法的讨论

Discussion on Calculation Method of Compression Resistance of Rock-socketed Piles in Technical Code for Building Pile Foundation

《建筑桩基技术规范》(JGJ 94—2008)嵌岩桩下压承载力的计算公式依据非扩底桩推导而得。为研究该公式对于扩底桩的适用情况,通过计算分析,受嵌岩段侧阻和端阻综合系数的影响,扩底桩嵌岩段承载力远小于规范公式的计算结果,规范计算结果偏于冒进。通过修正推导过程,得出了同时适用于非扩底桩和扩底桩的计算公式,扩大了原规范公式的适用范围。

The calculation formula of compression resistance of rock-socketed piles is derivated by non-expanded bore piles in Technical Code for Building Pile Foundation(JGJ 94—2008).In order to study applicability of this method to expanded bore piles,series of examples are calculated and analyzed.The results show that the compression resistance of rock-socketed segment of expanded bore piles is far less than the calculation with standard formula,which is affected by coefficient of colligation of shaft resistance and tip resistance of rock-socketed segment,and the standard calculation results are kind of rash advance.By modifying the process of derivation,a calculation formula which can be applied to both non-expanded bore piles and expanded bore piles has been generalized,which enlarges the application range of the original standard formula.