变角速度旋喷防渗墙应用技术研究

Research on the Applied Technology of Variable Angular Velocity Rotating Jet Grouting Cut-Off Wall

摘要: 为了解决传统的高压旋喷防渗墙成墙厚度偏大、钻孔间距较小的工程问题，研发了一种变角速度高压旋喷技术，开展了粉土、粉质黏土/黏土、沙壤土三种地层条件下的变角速度高压旋喷防渗墙试验，通过室内试验和现场试验，获得了变角速高压旋喷防渗墙工艺参数，验证了变角速度旋喷工程效果。结果表明，采用360˚范围内旋喷角速度的2级变速，可喷射出近似矩形断面的旋喷桩体；在粉土、粉质黏土/黏土、砂壤土地层和设定的工艺参数下，可分别喷射出0.5 m × 1.4 m~1.6 m、0.3 m × 1.6 m、0.4 m × 1.4 m~1.6 m的近似矩形桩体；较传统的定角速度高压旋喷技术相比，成墙厚度降低，旋喷桩布孔间距增加1倍以上，可降低工程造价50%左右，施工工效提高约1倍左右；与摆喷防渗墙相比，墙体厚度均匀、抗变形能力强、防渗效果好。

Abstract: To solve the problems of a larger thickness of diaphragm wall and a smaller hole spacing with traditional high pressure jet grouting method, a high pressure rotary jet method with variable angular velocity was developed and the test of high pressure rotary jet grouting with variable angular velocity in silty soil, silty clay/clay and sandy soils was carried out. The process param-eters of this method were obtained through laboratory and field tests and the engineering effect of the rotary jet with variable angular velocity was also verified. The results show that the ro-tating jet grouting pile with approximately rectangular section can be ejected out by the second-ary stage of rotational spray angular velocity within the 360-degree. Similar rectangular piles of 0.5 m × 1.4 m~1.6 m, 0.3 m × 1.6 m, 0.4 m × 1.4 m~1.6 m can be jetted out in setting process pa-rameters in the formations which mainly consist of silty soil, silty clay/clay, sandy loam stratum, respectively. Compared with the traditional high-pressure rotary injection technology with fixed angular velocity, this method has two notable features: the thickness of diaphragm wall is re-duced and hole spacing for jet grouting piles is increased by more than 1 times, which can re-duce the project cost by about 50% and improve the construction efficiency by approximately 1 time. Compared with jet-grouted cutoff wall methods, the high-pressure jet grouting method has characteristics of uniform thickness of diaphragm wall, high strength, and good seepage proof property.