钻孔灌注桩单桩竖向承载力判定方法在武汉某工程中的对比研究

Comparative Study on Determining Method of Vertical Bearing Capacity of Single Bored Pile in a Project in Wuhan

钻孔灌注桩单桩竖向承载力R_a依据现有建筑基桩检测技术规范和桩基工程手册,由单桩竖向极限承载力Q_u或桩顶沉降量s确定。单桩竖向极限承载力Q_u的判定方法主要根据竖向荷载-沉降(Q-s)曲线、沉降-时间对数(s-lg t)曲线和沉降-竖向荷载对数(s-lgQ)曲线进行判断;桩顶沉降量s的取值根据桩基工程手册和设计要求确定。根据这四种方法判定时,钻孔灌注桩单桩竖向承载力R_a的判定结果存在分歧。依据建筑基桩检测技术规范和桩基工程手册,对四种方法判定出的不同单桩竖向承载力R_a,进行分析对比,提出利用(Q-s)和(s-lgt)曲线综合判断的方法,为以后类似钻孔灌注桩单桩竖向承载力的确定提供相关参考方法。

based on the existing inspection technical specification of building piles and the pile foundation engineering manual,The vertical bearing capacity R_a of single pile of bored pile is determined by vertical ultimate bearing capacity Q_u of pile or settlement of pile top s.The determination method of vertical ultimate bearing capacity Q_u of single pile is mainly based on vertical load-settlement(Q-s)curve,settlement-time logarithm(s-lgt)curve and settlement-vertical load logarithm(s-lgQ)curve.The value of pile top settlement s is determined by pile foundation engineering manual and design requirements.Through these four methods,there are differences in the determination results of vertical bearing capacity of single bored pile.According to the inspection technical specification of building piles and the pile foundation engineering manual,analyzing and comparing the different vertical bearing capacity R_a of single pile determined by four methods,a method is proposed of judging the vertical bearing capacity of single bored pile by using(Q-s)and(s-lgt)curves,which provides a reference method for determining the vertical bearing capacity of similar bored pile in the future.