| 二重管旋喷工法成桩直径实用计算方法 |
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| 引用本文： | 韩立志,王志丰.二重管旋喷工法成桩直径实用计算方法[J].中国公路学报,2019,32(3):128-134. |
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| 作者姓名： | 韩立志 王志丰 |
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| 作者单位： | 1. 交通运输部公路科学研究院, 北京 100088;
2. 长安大学 陕西省公路桥梁与隧道重点实验室, 陕西 西安 7100064 |
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| 基金项目： | 国家自然科学基金项目（41702287）；中央高校基本科研业务费专项资金项目（300102218517） |
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| 摘 要： | 为了解决二重管旋喷工法成桩直径的预测问题,通过对二重管法成桩过程的理论分析,建立了可以考虑压缩空气影响的二重管法成桩直径的计算方法,并给出了相应的详细计算步骤。二重管法施工期间,压缩空气包裹高压水泥浆射流可以有效降低射流速度沿喷射距离的衰减速率,增强高压射流对土体的切削效应,使得高压旋喷桩的成桩直径明显增加,提高旋喷工法对软土地基的加固效果。所提出的实用计算方法可以有效考虑土性参数、旋喷参数以及压缩空气的影响。以旋喷施工时的空气喷射压力为主要控制参数,通过回归分析提出了可以表达压缩空气对成桩直径增大效应的定量计算公式。针对二重管法施工中压缩空气的常用压力范围0.5～1.5 MPa,得到了压缩空气包裹高压射流对旋喷桩成桩直径的增大比例,为27%～81%,这与工程实践经验非常接近(一般压缩空气可以提升桩径的范围为30%～90%)。以温州深厚软土地区的二重管法工程实例为依托,根据旋喷施工参数与土性参数,采用所提出的计算方法与成桩直径的现场实测结果进行了对比分析。分析结果表明:对于2根试桩C1和C2(实测直径分别为1.08,1.12 m),应用所提出计算方法产生的相对误差分别为5.6%和6.3%(计算直径分别为1.02,1.05 m),由此可见所提方法可以满足工程设计与施工的要求。
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| 关 键 词： | 隧道工程 地基处理 高压旋喷技术 理论分析 工程应用 成桩直径 |
| 收稿时间： | 2018-06-07 |
Practical Method to Predict Diameter of Jet Grout Column by Double Fluid System |
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| HAN Li-zhi,WANG Zhi-feng.Practical Method to Predict Diameter of Jet Grout Column by Double Fluid System[J].China Journal of Highway and Transport,2019,32(3):128-134. |
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| Authors: | HAN Li-zhi WANG Zhi-feng |
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| Affiliation: | 1. Research Institute of Highway Ministry of Transport, Beijing 100088, China;
2. Key Laboratory for Bridge and Tunnel of Shaanxi Province, Chang'an University, Xi'an 710064, Shaanxi, China |
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| Abstract: | To provide a reasonable prediction of the diameter of a jet grout column by a double fluid system, a method for estimating the diameter of the jet grout column was developed based on theoretical analysis of the construction process by a double fluid system. This method can consider the effect of compressed air. During the construction of the double-fluid system, the rate of decay for the velocity of the injected fluid can be effectively reduced using the compressed air surrounding the fluid, which can enlarge the erosion effect on soil by the highly pressurized fluid and increase the diameter of the jet grout column. Considering the pressure of compressed air, an equation for representing the effect of compressed air on increasing the diameter of the jet grout column was derived based on regression analysis. For the typical range of air pressure of 0.5-1.5 MPa, it was demonstrated that increasing the jet grout column diameter arising from the use of a compressed air shroud in the double system is 27%-81%, which is very close to the engineering experience (compressed air can increase the diameter by 30%-90%). A case history with the double fluid system was conducted in the soft clay of Wenzhou, and the measured data and calculated data of the jet grout column diameter were compared according to the jetting parameters and soil properties. The results indicate that, for two columns C1 and C2 (the measured values are 1.08 and 1.12 m, respectively), the relative error between the measured and calculated data is approximately 5.6% and 6.3%, respectively (the predicted values are 1.02 and 1.05 m, respectively), which can meet the needs of design and construction. |
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| Keywords: | tunnel engineering ground improvement jet grouting theoretical analysis field application diameter of jet grout column |
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