黄土地区高压旋喷桩施工挤土效应预测方法研究

Research on prediction method of extrusion effect of high pressure jet grouting pile installation in loess area

高压旋喷桩作为一种方便高效的复合地基加固措施,适用于湿软黄土地区路基帮宽段地基加固。高压旋喷桩施工注浆期间中会挤压周边土体产生变形,从而影响线路的安全运营。以某高速铁路引入既有城际铁路路基帮宽段工程为背景,通过对高压旋喷桩单桩施工挤土过程的简化分析,将施工注浆过程简化为半无限土体中一系列球形空腔膨胀的过程,提出了考虑施工参数与土体参数的单根高压旋喷桩施工引起土体位移的计算方法;给出了施工结束时土体侧向位移及垂向位移计算公式;根据量纲分析提出了球形空腔半径的计算公式,并将理论预测结果与现场试验结果进行对比,证明了该方法的可靠性。通过该方法进行参数化分析,结果表明:随着土层深度的递增,土体垂向位移不断减小,侧向位移先增大后减小;黄土地区单桩施工影响范围约为10倍成桩半径。

The high pressure jet grouting pile,as a convenient and efficient composite foundation reinforcement measure,is suitable for the foundation reinforcement of the wide section of the subgrade slope in the wet and soft loess area.During the grouting of high-pressure jet grouting pile installation,the surrounding soil will be squeezed and deformed,thus affecting the safe operation of the line.Based on the introduction of a high-speed railway into the widening section of the existing intercity railway subgrade,the installation grouting process is simplified into a series of spherical cavity expansion processes in the semi-infinite soil through the simplified analysis of the soil squeezing process in the installation of a single high pressure jet grouting pile,and a calculation method for the soil displacement caused by the installation of a single high pressure jet grouting pile considering the installation parameters and soil parameters is proposed;The formulas for calculating the lateral and vertical displacement of soil mass at the end of installation are given;According to dimensional analysis,a formula for calculating the radius of spherical cavity is proposed,and the theoretical prediction results are compared with the field test results,which validates the reliability of the method.The results indicate that with the increase of soil depth,the vertical displacement of soil decreases,while the lateral displacement increases first and then decreases;The influence range of single pile installation in loess area is about 10 times of pile forming radius.