爆扩桩抗拔极限承载力计算方法综述

A review of computation ways of ultimate bearing capacity of uplift explosive-enlarged piles

为了更好地研究爆扩桩抗拔极限承载力计算方法,总结了国内外计算爆扩桩极限承载力的方法。结合两组试桩试验,将试验结果与各种方法的计算值作比较。结果表明:规范算法计算结果比实际值小50%左右,过于保守忽略了桩体自重,不能充分地计算承载力值;圆柱面剪切法计算结果比实际值相差大10%左右,不适宜用来估计承载力值;一些学者依据有限元模拟,提出了扩大头段产生局部破坏,破裂面曲线可以采用对数螺旋线表示,计算结果与试验值吻合较好,适用于不同分层土体计算。也为以后类似抗拔桩设计提供参考和建议。

In order to study the computation ways of ultimate bearing capacity of uplift explosive enlarged-piles,it summarizes different computation ways of uplift pile by the research results of domestic and overseas scholars.Combining with two tests of pile,the comparative analysis on different calculation results is performed.The result show that the calculation value of standard method is approximately half of the test value,excessively conservative and cannot adequately take advantage of the bearing capacity,ignoring the self weight of pile.However,the value of cylinder shear method is approximately 10%larger than actual value and not suitable to estimate the value of ultimate bearing capacity.According to numerical analysis,some scholar is supposed to form fracture surface of logarithmic-spiral line,the calculation results show good agreement with test results and they can all be used to compute the ultimate capacity of uplift piles under different soil conditions.Also it provides reference to design or similar uplift piles.