基于水-热-力耦合模型的钻孔灌注桩承载力影响因素分析
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摘要
针对广大寒区普遍存在的冻胀-融沉影响桩基承载力问题,以清水河大桥灌注桩为例,基于建立的饱和冻土水-热-力三场耦合模型及研发的3G2012软件系统,深入研究了温度变幅、桩和地基土的传导系数、导水系数、回冻时间等因素对其承载力的影响,揭示了其承载的内在热力学机理.结果表明:钻孔灌注桩承载力随温度发生波动变化,冬季桩基的极限承载力近似为夏季的1.2倍;地基的导水系数提高一个数量级,加剧了地基土中的水分迁移及冻胀融沉变形,进而影响桩基承载力;冻土回冻时间对桩基承载力也有较大影响.以上结论为寒区岩土工程的设计与施工提供量化的科学依据.
The bearing capacity of pile foundation is severely affected by the changes in seasonally freezing and thawing processes. By using a thermo-hydro-mechanical coupling model for saturation frozen soil and its analysis software 3G2012,the influences of temperature fluctuation,conductivity coefficient,transmissibility coefficient and refreezing time on the bearing capacity of cast-in-place pile in cold regions are studied in this paper,in which the cast-in-place piles in Qingshuihe Bridge are taken as an example. The study achievements reveal the thermo-dynamicsmechanism of the bearing capacity of cast-in-place pile. It is found that 1) bearing capacity shows a fluctuate change with temperature and the ultimate bearing capacity of the pile foundation in winter is about120% as it in summer; 2) when the transmissibility coefficient within subsoil has one order enhanced,the water migration will be more active and the frost heaving and thawing settlement processes will significantly intensify,affecting the pile's bearing capacity; 3) also,the process of refrozen has some influence on the bearing capacity of the pile. Further study may provide scientific basis for design and construction of projects in cold regions.
The bearing capacity of pile foundation is severely affected by the changes in seasonally freezing and thawing processes. By using a thermo-hydro-mechanical coupling model for saturation frozen soil and its analysis software 3G2012,the influences of temperature fluctuation,conductivity coefficient,transmissibility coefficient and refreezing time on the bearing capacity of cast-in-place pile in cold regions are studied in this paper,in which the cast-in-place piles in Qingshuihe Bridge are taken as an example. The study achievements reveal the thermo-dynamicsmechanism of the bearing capacity of cast-in-place pile. It is found that 1) bearing capacity shows a fluctuate change with temperature and the ultimate bearing capacity of the pile foundation in winter is about120% as it in summer; 2) when the transmissibility coefficient within subsoil has one order enhanced,the water migration will be more active and the frost heaving and thawing settlement processes will significantly intensify,affecting the pile's bearing capacity; 3) also,the process of refrozen has some influence on the bearing capacity of the pile. Further study may provide scientific basis for design and construction of projects in cold regions.
引文
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[12]Li Ning,Xu Bin.A new type of pile used in frozen soil foundation[J].Cold Regions Science and Technology,2008,53:355-368.
[13]Chen Feixiong.The Fully Coupled Modeling of the ThermalM oisture-Deformation Behavior for the Saturated Freezing Soils[D].Xi'an:Xi'an University of Technology,2001.[陈飞熊.饱和正冻土温度场、水分场和变形场三场耦合理论构架[D].西安:西安理工大学,2001.]
[14]Lai Yuanming,Zhang Mingyi,Liu Zhiqiang,et al.Cooling effect analysis of the ripped-rock embankment for Qinghai-Tibet Railw ay w ith open boundary condition[J].Science in China(Series D:Earth Sciences),2006,49(7):764-772.[赖远明,张明义,刘志强,等.开放边界条件下青藏铁路抛石路基的降温效果分析[J].中国科学(D辑:地球科学),2005,35(6):578-585.]
[15]Pan Yanxia.Research on the Analysis Thermodynamics of CastIn-Place Pile in High-Temperature Permafrost and Pile M odel Test in Frozen Soil[D].Lanzhou:Lanzhou Jiaotong University,2011.[潘艳霞.高温多年冻土钻孔灌注桩热力学分析及模型试验研究[D].兰州:兰州交通大学,2011.]
[16]Ding Zhaojun.Construction of drilling hole and pouring pile in the area of frozen soil of many years[J].Journal of Shijiazhuang Institute of Railw ay Engineering,2003,2(2):38-41.[丁兆军.多年冻土区钻孔灌注桩施工[J].石家庄铁道工程职业技术学院学报,2003,2(2):38-41.]
[17]Wu Zhijian,Che Ailan,Wang Ping,et al.Test study and numerical analysis of seismic response of pile foundation of bridge at permafrost regions along Qinghai-Tibet Railroad[J].Rock and Soil M echanics,2010,30(11):3517-3523.[吴志坚,车爱兰,王平,等.青藏铁路多年冻土区桥梁桩基础地震响应的试验研究与数值分析[J].岩土力学,2010,30(11):3517-3523.]
[18]LüXiaoliang,Zhou Guoqing,Bie Xiaoyong.Experimental investigation of the bearing capacity of piles in unfrozen soil and high-temperature permafrost[J].Geotechnical Engineering Technique,2007,21(13):160-163.[吕晓亮,周国庆,别小勇.未冻土和高温冻土中桩基承载性能试验研究[J].岩土工程技术,2007,21(13):160-163.]
[2]Jia Xiaoyun,Zhu Yongquan,Li Wenjiang.Study of ground temperature field during pile foundation construction in permafrost regions[J].Rock and Soil M echanics,2004,25(7):1139-1142.[贾晓云,朱永全,李文江.高原冻土区桩基施工温度场研究[J].岩土力学,2004,25(7):1139-1142.]
[3]Wang Jianzhou,Li Shengsheng,Zhou Guoqing,et al.Analysis of bearing capacity of pile foundation in high temperature permafrost regions w ith permafrost table descending[J].Chinese Journal of Rock M echanics and Engineering,2006,25(S2):4226-4232.[王建州,李生生,周国庆,等.冻土上限下移条件下高温冻土桩基承载力分析[J].岩石力学与工程学报,2006,25(S2):4226-4232.]
[4]Foriero A,Ladanyi B.Finite element simulation of interface problem for laterally loaded piles in permafrost[J].Cold Regions Science and Technology,1995,23(2):121-130.
[5]Chen Zhaoyu,Li Guoyu,Yu Qihao,et al.Study of thermal stability of cast-in-place pile foundations of the Qinghai-Tibet DC Transmission Project in permafrost region[J].Journal of Glaciology and Geocryology,2013,35(5):1209-1218.[陈赵育,李国玉,俞祁浩,等.青藏直流联网工程多年冻土区砼灌注桩基础长期热稳定性预测研究[J].冰川冻土,2013,35(5):1209-1218.]
[6]Yang Yong,Chen Rensheng,Ye Baisheng,et al.Heat and water transfer processes on the typical underlying surfaces of frozen soil in cold regions(I):M odel comparison[J].Journal of Glaciology and Geocryology,2013,35(6):1545-1554.[阳勇,陈仁升,叶柏生,等.寒区典型下垫面冻土水热过程对比研究(I):模型对比[J].冰川冻土,2013,35(6):1545-1554.]
[7]Yang Yong,Chen Rensheng,Ye Baisheng,et al.Heat and water transfer processes on the typical underlying surfaces of frozen soil in cold regions(II):Water and heat transfer[J].Journal of Glaciology and Geocryology,2013,35(6):1555-1563.[阳勇,陈仁升,叶柏生,等.寒区典型下垫面冻土水热过程对比研究(II):水热传输[J].冰川冻土,2013,35(6):1555-1563.]
[8]Abdrabbo M,Gaaver E.Installation effects of auger cast-inplace piles[J].Alexandria Engineering Journal,2012,51:281-292.
[9]Zhang Wei,Wang Genxu,Zhou Jian,et al.Simulating the water-heat processes in permafrost regions in the Tibetan Plateau based on Coup M odel[J].Journal of Glaciology and Geocryology,2012,34(5):1099-1109.[张伟,王根绪,周剑,等.基于Coup Model的青藏高原多年冻土区土壤水热过程模拟[J].冰川冻土,2012,34(5):1099-1109.]
[10]Hong Tao,Liang Sihai,Sun Yu,et al.Analyzing the factors that impact on the heat conductivity coefficient and applying them to simulate the depth of permafrost active layer in the headw aters of the Yellow River[J].Journal of Glaciology and Geocryology,2013,35(4):824-833.[洪涛,梁四海,孙禹,等.黄河源区多年冻土热传导系数影响因素分析及其在活动层厚度模拟中的应用[J].冰川冻土,2013,35(4):824-833.]
[11]Li Yongbo,Zhang Hongru,Quan Kejiang,et al.Experimental study of model pile foundations under lateral dynamic load in frozen and thaw ed soils[J].Rock and Soil M echanics,2012,33(2):433-438.[李永波,张鸿儒,全克江,等.冻融条件下模型桩基水平动力试验研究[J].岩土力学,2012,33(2):433-438.]
[12]Li Ning,Xu Bin.A new type of pile used in frozen soil foundation[J].Cold Regions Science and Technology,2008,53:355-368.
[13]Chen Feixiong.The Fully Coupled Modeling of the ThermalM oisture-Deformation Behavior for the Saturated Freezing Soils[D].Xi'an:Xi'an University of Technology,2001.[陈飞熊.饱和正冻土温度场、水分场和变形场三场耦合理论构架[D].西安:西安理工大学,2001.]
[14]Lai Yuanming,Zhang Mingyi,Liu Zhiqiang,et al.Cooling effect analysis of the ripped-rock embankment for Qinghai-Tibet Railw ay w ith open boundary condition[J].Science in China(Series D:Earth Sciences),2006,49(7):764-772.[赖远明,张明义,刘志强,等.开放边界条件下青藏铁路抛石路基的降温效果分析[J].中国科学(D辑:地球科学),2005,35(6):578-585.]
[15]Pan Yanxia.Research on the Analysis Thermodynamics of CastIn-Place Pile in High-Temperature Permafrost and Pile M odel Test in Frozen Soil[D].Lanzhou:Lanzhou Jiaotong University,2011.[潘艳霞.高温多年冻土钻孔灌注桩热力学分析及模型试验研究[D].兰州:兰州交通大学,2011.]
[16]Ding Zhaojun.Construction of drilling hole and pouring pile in the area of frozen soil of many years[J].Journal of Shijiazhuang Institute of Railw ay Engineering,2003,2(2):38-41.[丁兆军.多年冻土区钻孔灌注桩施工[J].石家庄铁道工程职业技术学院学报,2003,2(2):38-41.]
[17]Wu Zhijian,Che Ailan,Wang Ping,et al.Test study and numerical analysis of seismic response of pile foundation of bridge at permafrost regions along Qinghai-Tibet Railroad[J].Rock and Soil M echanics,2010,30(11):3517-3523.[吴志坚,车爱兰,王平,等.青藏铁路多年冻土区桥梁桩基础地震响应的试验研究与数值分析[J].岩土力学,2010,30(11):3517-3523.]
[18]LüXiaoliang,Zhou Guoqing,Bie Xiaoyong.Experimental investigation of the bearing capacity of piles in unfrozen soil and high-temperature permafrost[J].Geotechnical Engineering Technique,2007,21(13):160-163.[吕晓亮,周国庆,别小勇.未冻土和高温冻土中桩基承载性能试验研究[J].岩土工程技术,2007,21(13):160-163.]
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