水平旋喷成桩引起超静孔隙水压力研究

长安大学 陕西省公路桥梁与隧道重点实验室,陕西 西安 710064

隧道工程; 地基处理; 水平旋喷桩; 现场试验; 超静孔隙水压力

Investigation of excess pore water pressure caused by installation of horizontal jet grout columns
WANG Zhi-feng,WANG Ya-qiong,XIE Yong-li

(Key Laboratory for Highway Bridge and Tunnel Engineering of Shaanxi Province,Chang'an University,Xi'an 710064,China)

tunnelling engineering; ground improvement; horizontal jet grout column; field test; excess pore water pressure

DOI: 10.13800/j.cnki.xakjdxxb.2016.0210

备注

为研究水平旋喷成桩对周围地层的影响问题,优化水平旋喷桩设计施工,采用现场试验的方法研究了水平旋喷成桩引起超静孔隙水压力的变化规律,探讨了水平旋喷施工的影响范围。水平旋喷成桩对周围地层的扰动较大,引发土体中产生较高的超静孔隙水压力。通过对水平旋喷成桩过程的分析,可以分为高压射流形成阶段,高压射流与土体相互作用阶段和水泥土固化阶段。研究结果表明:水平旋喷成桩产生的超静孔隙水压力随着施工阶段的改变而变化,高压流体注入时有所增大,而钻喷杆卸杆时则有所减小; 成桩引起的最大超静孔隙水压力与注浆压力呈近似线性关系; 随着施工距离的增大,超静孔隙水压力不断减小,当施工距离大于15 m时,基本可以忽略成桩引起的超静孔隙水压力; 以水平旋喷成桩引起地层反应小于5%作为影响范围控制值,则超静孔隙水压力影响范围约为15~20倍成桩半径,可以采用指数函数的形式表达超静孔隙水压力与施工距离的关系。

In order to investigate the effect of jet grouting construction on the surroundings and to optimize the design and construction technology of jet grouting,based on a field test,the variation laws of excess pore water pressure caused by installing horizontal jet grout columns were investigated,and the influential range due to horizontal jet grouting construction was discussed.The great disturbance of surroundings can be observed during the installation of horizontal jet grout columns,which will cause a higher excess pore water pressure.Based on the analysis of the construction process of horizontal jet grouting,it can be divided into three stages:formation of high pressurized fluid,interaction between the high pressurized fluid and the soil,and stabilization of cemented soils.The investigation results show that:the excess pore water pressure changes with the variation of construction process of horizontal jet grouting process,and the excess pore water pressure will arise after the injection of high pressurized fluid,and has a reduction when the rod is removed; the relationship between the excess pore water pressure and jetting pressure can be described in an approximately linear way; the excess pore water pressure decreased with the increase of distance to the construction position,and the excess pore water pressure caused by horizontal jet grout columns installation can be ignored when the distance is larger than 15 m; if the change of ground response is less than 5%,the influential range caused by installation of jet grouted columns was between 15 and 20 times the radius of column,and the relationship between the excess pore water pressure and the distance can be described in a power function.