复合式后压浆钻孔灌注桩承载力特征研究

Research on Composite Post-Grouting Bored Pile Load-Bearing Characteristics

复合式后压浆是将开式和闭式结合为一体的桩底压浆方式,保留开式注浆管,将闭式胶囊一分为二,钢板中间预留圆孔,在桩端形成扩大头,提高基桩承载力。本文结合山西G2003太原绕城高速公路西陵井枢纽主线2号桥工程3根试桩静载试验结果,对基桩极限承载力、桩身轴力以及桩端阻力进行综合分析。结果表明,端阻分担荷载比为17.0%~44.5%,各侧阻和端阻实测值均大于复合式后压浆计算公式中相关参数推荐值,验证了复合式后压浆灌注桩的工程效果,可为复合式后压浆钻孔灌注桩的其他项目提供一些借鉴。

Composite post-grouting is a pile bottom grouting method that combines open and closed grouting.The open grouting pipe is reserved,the closed capsule is divided into two parts,and a circular hole is reserved in the middle of the steel plate to form an enlarged head at the pile end to improve the bearing capacity of the foundation pile.This paper is based on the static load test results of three test piles of the No.2 bridge project of Xilingjing hub main line of the G2003 Ring Expressway in Taiyuan,Shanxi,through the comprehensive analysis of the ultimate bearing capacity of the foundation pile,the axial force of the pile shaft and the pile end resistance,the results show that the load sharing ratio of the end resistance is 17.0%~44.5%,and the measured values of each side resistance and end resistance are greater than the recommended values of relevant parameters in the composite post-grouting calculation formula.The engineering effect of composite post-grouting cast-in-place pile is verified,which can provide some reference for other projects of composite post-grouting cast-in-place pile.