二重管旋喷工法成桩直径实用计算方法
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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。
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.
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.
引文
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[14]HO C E.Fluid-soil Interaction Model for Jet Grouting[C]//HURLEY T M,JOHNSEN L F.Proceedings of Grouting for Ground Improvement:Innovative Concepts and Applications.Reston:ASCE,2007:1-10.
[15]SHEN Shui-long,WANG Zhi-feng,YANG Jun,et al.Generalized Approach for Prediction of Jet Grout Column Diameter[J].Journal of Geotechnical and Geoenvironmental Engineering,2013,139(12):2060-2069.
[16]FLORA A,MODONI G,LIPER S,et al.The Diameter of Single,Double and Triple Fluid Jet Grouting Columns:Prediction Method and Field Trial Results[J].Géotechnique,2013,63(11):934-945.
[17]OCHMAN′SKI M,MODONI G,BZWKA J.Prediction of the Diameter of Jet Grouting Columns with Artificial Neural Networks[J].Soils and Foundations,2015,55(2):425-436.
[18]王志丰.高压旋喷成桩及其环境影响的施工机理研究[D].上海:上海交通大学,2013.WANG Zhi-feng.Investigation of Construction Mechanism of Column Formation and Impact on Surroundings During Jet Grouting[D].Shanghai:Shanghai Jiao Tong University,2013.
[19]龙纲要.影响旋喷桩桩径因素的探讨[J].化工矿产地质,2003,25(4):247-250.LONG Gang-yao.Approach to Factors Determining the Diameter of Rotating Spraying Piles[J].Geology of Chemical Minerals,2003,25(4):247-250.
[20]LANARDI P.Ground Improvement by Means of Jet Grouting[J].Proceedings of the Institution of Civil Engineers-ground Improvement,1997,1(2):65-85.
[21]寇晓强,杨京方,叶国良,等.盾构近距离穿越群桩旋喷加固效果分析[J].铁道工程学报,2011,28(11):98-103.KOU Xiao-qiang,YANG Jing-fang,YE Guo-liang,et al.Study on Reinforcement Effect of Shield Tunnel Adjacent to Existing Pile Foundation with Churning Pile[J].Journal of Railway Engineering Society,2011,28(11):98-103.
[22]安关峰,张洪彬,刘添俊.旋喷群桩复合地基承载特性的数值分析[J].岩土力学,2012,33(3):906-912.AN Guang-feng,ZHANG Hong-bin,LIU Tian-jun.Numerical Analysis of Bearing Characteristics of Composite Subgrade Reinforced by Chemical Churning Pile Groups[J].Rock and Soil Mechanics,2012,33(3):906-912.
[23]NI J C,CHENG W C.Quality Control of Double Fluid Jet Grouting below Groundwater Table:Case History[J].Soils and Foundations,2014,54(6):1039-1053.
[24]WANG Zhi-feng,SHEN Shui-long,YANG Jun.Estimation of the Diameter of Jet-grouted Column Based on Turbulent Kinematic Flow Theory[C]//JOHNSEN L F,DRUCE D A.Proceedings of the4th International Conference on Grouting and Deep Mixing 2012.Reston:ASCE,2012:2044-2051.
[25]MODONI G,FLORA A,LIRER S,et al.Design of Jet Grouted Excavation Bottom Plugs[J].Journal of Geotechnical and Geoenvironmental Engineering,2016,142(7):04016018.
[2]BURKE G K.Jet Grouting Systems:Advantages and Disadvantages[C]//TURNER J R,MAYNE PW.Proceedings of GeoSupport Conference 2004.Reston:ASCE,2004:75-87.
[3]WANG Z F,SHEN S L,HO C E,et al.Investigation of Field Installation Effects of Horizontal Twinjet Grouting in Shanghai Soft Soil Deposits[J].Canadian Geotechnical Journal,2013,50(3):288-297.
[4]刘钟,柳建国,张义,等.隧道全方位高压喷射注浆拱棚超前支护新技术[J].岩石力学与工程学报,2009,28(1):59-65.LIU Zhong,LIU Jian-guo,ZHANG Yi,et al.New Technique of Rotary Horizontal Jet Grouting for Arched Tunnel Pre-support[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(1):59-65.
[5]张晓,杨建国,王运周,等.水平旋喷桩预支护在软弱黄土隧道中的试验研究[J].现代隧道技术,2010,47(1):36-40.ZHANG Xiao,YANG Jian-guo,WANG Yun-zhou,et al.Application of Pre-supporting with Horizontal Jet Grouting Piles for a Weak Loess Tunnel[J].Modern Tunnelling Technology,2010,47(1):36-40.
[6]狄宏规,冷伍明,周顺华,等.朔黄重载铁路路基斜向高压旋喷桩加固效果[J].同济大学学报:自然科学版,2013,41(12):1818-1823.DI Hong-gui,LENG Wu-ming,ZHOU Shun-hua,et al.Reinforcement Effect of Inclined High Pressure Jet Grouting Piles for Shuohuang Heavy Haul Railway[J].Journal of Tongji University:Natural Science,2013,41(12):1818-1823.
[7]SHEN Shui-long,WANG Zhi-feng,SUN Wen-juan,et al.A Field Trial of Horizontal Jet Grouting Using the Composite-pipe Method in the Soft Deposits of Shanghai[J].Tunnelling and Underground Space Technology,2013,35:142-151.
[8]WANG Z F,SHEN S L,HO C E,et al.Jet Grouting for Mitigation of Installation Disturbance[J].Proceedings of the ICE-Geotechnical Engineering,2014,167(6):526-536.
[9]CROCE P,FLORA A.Analysis of Single-fluid Jet Grouting[J].Géotechnique,2000,50(6):739-748.
[10]SHEN S L,WANG Z F,HORPIBULSUK S,et al.Jet Grouting with a Newly Developed Technology:The Twin-jet Method[J].Engineering Geology,2013,152(1):87-95.
[11]MODONI G,BZWKA J.Analysis of Foundations Reinforced with Jet Grouting[J].Journal of Geotechnical and Geoenvironmental Engineering,2012,138(12):1442-1454.
[12]SHIBAZAKI M.State of Practice of Jet Grouting[C]//JOHNSEN L F,BRUCE D A,BYLE M.Grouting 2003:Grouting and Ground Treatment.Reston:ASCE,2003:198-217.
[13]MODONI G,CROCE P,MONGIOVI L.Theoretical Modelling of Jet Grouting[J].Géotechnique,2006,56(5):335-347.
[14]HO C E.Fluid-soil Interaction Model for Jet Grouting[C]//HURLEY T M,JOHNSEN L F.Proceedings of Grouting for Ground Improvement:Innovative Concepts and Applications.Reston:ASCE,2007:1-10.
[15]SHEN Shui-long,WANG Zhi-feng,YANG Jun,et al.Generalized Approach for Prediction of Jet Grout Column Diameter[J].Journal of Geotechnical and Geoenvironmental Engineering,2013,139(12):2060-2069.
[16]FLORA A,MODONI G,LIPER S,et al.The Diameter of Single,Double and Triple Fluid Jet Grouting Columns:Prediction Method and Field Trial Results[J].Géotechnique,2013,63(11):934-945.
[17]OCHMAN′SKI M,MODONI G,BZWKA J.Prediction of the Diameter of Jet Grouting Columns with Artificial Neural Networks[J].Soils and Foundations,2015,55(2):425-436.
[18]王志丰.高压旋喷成桩及其环境影响的施工机理研究[D].上海:上海交通大学,2013.WANG Zhi-feng.Investigation of Construction Mechanism of Column Formation and Impact on Surroundings During Jet Grouting[D].Shanghai:Shanghai Jiao Tong University,2013.
[19]龙纲要.影响旋喷桩桩径因素的探讨[J].化工矿产地质,2003,25(4):247-250.LONG Gang-yao.Approach to Factors Determining the Diameter of Rotating Spraying Piles[J].Geology of Chemical Minerals,2003,25(4):247-250.
[20]LANARDI P.Ground Improvement by Means of Jet Grouting[J].Proceedings of the Institution of Civil Engineers-ground Improvement,1997,1(2):65-85.
[21]寇晓强,杨京方,叶国良,等.盾构近距离穿越群桩旋喷加固效果分析[J].铁道工程学报,2011,28(11):98-103.KOU Xiao-qiang,YANG Jing-fang,YE Guo-liang,et al.Study on Reinforcement Effect of Shield Tunnel Adjacent to Existing Pile Foundation with Churning Pile[J].Journal of Railway Engineering Society,2011,28(11):98-103.
[22]安关峰,张洪彬,刘添俊.旋喷群桩复合地基承载特性的数值分析[J].岩土力学,2012,33(3):906-912.AN Guang-feng,ZHANG Hong-bin,LIU Tian-jun.Numerical Analysis of Bearing Characteristics of Composite Subgrade Reinforced by Chemical Churning Pile Groups[J].Rock and Soil Mechanics,2012,33(3):906-912.
[23]NI J C,CHENG W C.Quality Control of Double Fluid Jet Grouting below Groundwater Table:Case History[J].Soils and Foundations,2014,54(6):1039-1053.
[24]WANG Zhi-feng,SHEN Shui-long,YANG Jun.Estimation of the Diameter of Jet-grouted Column Based on Turbulent Kinematic Flow Theory[C]//JOHNSEN L F,DRUCE D A.Proceedings of the4th International Conference on Grouting and Deep Mixing 2012.Reston:ASCE,2012:2044-2051.
[25]MODONI G,FLORA A,LIRER S,et al.Design of Jet Grouted Excavation Bottom Plugs[J].Journal of Geotechnical and Geoenvironmental Engineering,2016,142(7):04016018.