高压脉冲放电在大直径扩底灌注桩中的应用技术研究

Research on application technology of high voltage pulse discharge for large diameter cast‑in‑place belled piles

本文主要研究了金属丝电爆炸产生的压力冲击波作用在土层孔壁上,在桩底部挤压土体形成扩底桩。建立了金属丝爆炸能量与冲击波压力之间的关系函数与仿真模型,分析了放电参数与冲击波强度的关系;建立了冲击波压力与土体变形之间的关系,计算出粘性土体变形量所需要的压力大小;制作扩底桩、直桩模型,验证金属丝电爆炸荷载作用下土体受力变形特性,并对两种桩型承载力及抗拔力性能进行对比分析。利用高压脉冲扩底技术模型试验中的电学参数及工艺参数,构建国内首根直径0.8 m的高压脉冲扩底桩,完成“灌-扩”一体高压脉冲扩底工法的开发。

This paper focuses on the pressure shock wave generated by the electric explosion of the wire acts on the hole wall of the soil layer and form the belled piles caused by squeezing the soil at the bottom of the pile.The relationship function and simulation model between the explosive energy of the wire and the shock wave pressure are established,and the relationship between the discharge parameters and the shock wave intensity is analyzed.The relationship between shock wave pressure and soil deformation is established,and the pressure required for the deformation of clay soil is calculated.The models of belled pile and equal diameter pile were made to verify the deformation characteristics of soil under the electric explosion of the wire,and the bearing capacity and pullout resistance of the two piles were compared and analyzed.Based on the electrical and technological parameters of the high⁃voltage pulse bottom expanding technology model test,the first high⁃voltage pulse belled pile with a diameter of 0.8m was constructed in China,and the“irrigation⁃expansion”integrated construction method was developed.