考虑温度影响的能源桩桩–土界面荷载传递模型
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摘要
为深入揭示温度对能源桩力学特性的影响,考虑能源桩桩–土界面法向温度应力增量对初始剪切刚度的影响,对传统桩–土界面荷载传递双曲线模型进行修正,并通过合理假设桩身及桩周土中温度场分布,计算得到桩–土界面法向温度应力,建立考虑温度影响的桩–土界面荷载传递模型。同时,选取宁波地区典型软黏土开展不同温度下能源桩承载力特性模型试验,将计算结果与模型试验结果进行对比,结果表明:升温有助于提高能源桩单桩的承载力;桩周土温度、Q-s曲线计算结果与实测值较为一致,验证了能源桩桩–土界面荷载传递模型的合理性;能源桩运行使得桩、土体温度升高,桩、土之间的法向应力增大,相同条件下能源桩上部(0.7 m以上)桩侧摩阻力随温度的升高(30℃→45℃→60℃)有一定的增大,发挥充分,下部反之。
To reveal the influence of temperature on the mechanical properties of energy piles,a traditional hyperbolic model for pile-soil interface load transfer was revised by considering the influence of the normal temperature stress increment on the initial shear stiffness at the interface of pile and soil. The temperature field distributions in the pile body and surrounding soil were assumed,and the normal temperature stress of the pile-soil interface was calculated,then the load-transfer model of pile-soil interfaces considering the influence of temperature was established. The bearing capacity of energy piles in the typical soft clay in Ningbo area was studied by modelling test. The experimental results were compared with the calculated results. It is shown that the temperature helps to improve the bearing capacity of the energy pile,and that the calculated results of Q-s curve are consistent with the measured values,which verifies the rationality of the load transfer model of the energy pile considering the influence of temperature. The operation of energy piles leads to temperature increasing in pile and soil,and the normal stress between pile and soil increase too,which cause the shaft resistance of the upper part of the energy pile(above 0.7 m) to increase with temperature(30 ℃→45 ℃→60 ℃) under the same conditions of calculation,but in the lower part,the opposite occurs.
To reveal the influence of temperature on the mechanical properties of energy piles,a traditional hyperbolic model for pile-soil interface load transfer was revised by considering the influence of the normal temperature stress increment on the initial shear stiffness at the interface of pile and soil. The temperature field distributions in the pile body and surrounding soil were assumed,and the normal temperature stress of the pile-soil interface was calculated,then the load-transfer model of pile-soil interfaces considering the influence of temperature was established. The bearing capacity of energy piles in the typical soft clay in Ningbo area was studied by modelling test. The experimental results were compared with the calculated results. It is shown that the temperature helps to improve the bearing capacity of the energy pile,and that the calculated results of Q-s curve are consistent with the measured values,which verifies the rationality of the load transfer model of the energy pile considering the influence of temperature. The operation of energy piles leads to temperature increasing in pile and soil,and the normal stress between pile and soil increase too,which cause the shaft resistance of the upper part of the energy pile(above 0.7 m) to increase with temperature(30 ℃→45 ℃→60 ℃) under the same conditions of calculation,but in the lower part,the opposite occurs.
引文
[1]UESUGI M,KISHIDA H,TSUBAKIHARA Y.Friction between sand and steel under repeated loading[J].Soils and Foundations,1989,29(3):127-137.
[2]DESAI C S,DRUMM E C.Cyclic testing and modeling of interface[J].Journal of Geotechnical Engineering,1985,111(6):793-815.
[3]YIN Z Z,ZHU H,XU G H.A study of deformation in interface between soil and concrete[J].Computers and Geotechnics,1995,17(1):75-92.
[4]GóMEZ J E,FILZ G M,EBELING R M.Development of an improved numerical model for concrete-to-soil interfaces in soilstructure interaction analyses[R].Vicksburg:U.S.Army Engineer Research and Development Center,2000.
[5]SEED H B,REESE L C.The action of soft clay along friction piles[C]//Trans.Am.Soc.Civ.Engrs.,[S.l.]:[s.n.],1957(122):731-754.
[6]WONG K S,THE C I.Negative skin friction on piles in layered deposits[J].Journal of Geotechnical Engineering,ASCE,1995,121(6):457-465.
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[9]曹卫平.桩土界面荷载传递双曲线模型的改进及其应用[J].岩石力学与工程学报,2009,28(1):144-151.(CAO Weiping.An improved load transfer hyperbolic model for pile-soil interface and its application[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(10):144-151.(in Chinese))
[10]WANG B,BOUAZZA A,HABERFILED C.Preliminary observations from laboratory scale model geothermal pile subjected to thermalmechanical loading[C]//Geo-Frontiers Congress.Dallas,Texas:ASCE,2011:488-489.
[11]刘干斌,谢琦峰,范高飞,等.饱和黏土中热交换桩承载力特性模型试验研究[J].岩石力学与工程学报,2017,36(10):2 535-2 543.(LIU Ganbin,XIE Qifeng,FAN Gaofei,et al.Model test on bearing capacity characteristics of heat exchanger piles in saturated clays[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(10):2 535-2 543.(in Chinese))
[12]路宏伟,蒋刚,王昊,等.摩擦型能源桩荷载-温度现场联合测试与承载性状分析[J].岩土工程学报,2017,39(2):334-342.(LUHongwei,JIANG Gang,WANG Hao,et al.In-situ tests and thermomechanical bearing characteristics of friction geothermal energy piles[J].Chinese Journal of Geotechnical Engineering,2017,39(2):334-342.(in Chinese))
[13]ALONSO E E,JOSA A,LEDESMA A.Negative skin friction on piles:A simplified analysis and prediction procedure[J].Geotechnique,1984,34(3):341-357.
[14]赵海丰,桂树强,唐荣彬,等.螺旋型埋管能源桩传热模型的适用性及其试验验证[J].长江科学院院报,2017,34(4):111-116.(ZHAO Haifeng,GUI Shuqiang,TANG Rongbin,et al.Applicability of heat transfer model of energy pile with buried spiral pipe and its experimental verification[J].Journal of Yangtze River Scientific Research Institute,2017,34(4):111-116.(in Chinese))
[15]SURYATRIYASTUTI M E,MROUEH H,BURLON S.A load transfer approach for studying the cyclic behavior of thermo-active piles[J].Computers and Geotechnics,2014,55:378-391.
[16]李维特,黄保海,毕仲波.热应力理论分析及应用[M].北京:中国电力出版社,2004:94-95.(LI Weite,HUANG Baohai,BI Zhongbo.Theoretical analysis and application of thermal stress[M].Beijing:China Electric Power Press,2004:94-95.(in Chinese))
[17]FELLENIUS B H.Results from long-term measurement in piles of drag load and down drag[J].Canadian Geotechnical Journal,2006,43(4):409-430.
[18]SHINICHI Y,MADAN M.Reliability based load transfer characteristics of bored precast piles equipped with ground bulb in the pile toe region[J].Soils and Foundations,2004,44(3):57-68.
[19]中华人民共和国行业标准编写组.建筑桩基技术规范[S].北京:中国建筑工业出版社,1994.(The Professional Standards Compilation Group of People′s Republic of China.Technical code for building pile foundations[S].Beijing:China Architecture and Building Press,1994.(in Chinese))
[20]赵刚,李驰,斯日古楞.温度循环下桩土界面特性及桩侧摩阻力数值模拟[J].防灾减灾工程学报,2017,37(4):546-550.(ZHAOGang,LI Chi,Siriguleng.Friction characteristics of pile-soil interface under temperature cycles and numerical simulation of shaft resistance[J].Journal of Disaster Prevention and Mitigation Engineering,2017,37(4):546-550.(in Chinese))
[2]DESAI C S,DRUMM E C.Cyclic testing and modeling of interface[J].Journal of Geotechnical Engineering,1985,111(6):793-815.
[3]YIN Z Z,ZHU H,XU G H.A study of deformation in interface between soil and concrete[J].Computers and Geotechnics,1995,17(1):75-92.
[4]GóMEZ J E,FILZ G M,EBELING R M.Development of an improved numerical model for concrete-to-soil interfaces in soilstructure interaction analyses[R].Vicksburg:U.S.Army Engineer Research and Development Center,2000.
[5]SEED H B,REESE L C.The action of soft clay along friction piles[C]//Trans.Am.Soc.Civ.Engrs.,[S.l.]:[s.n.],1957(122):731-754.
[6]WONG K S,THE C I.Negative skin friction on piles in layered deposits[J].Journal of Geotechnical Engineering,ASCE,1995,121(6):457-465.
[7]RANDOLPH M F,WORTH C P.Analysis of deformation of vertically loaded piles[J].Journal of Geotechnical Engineering,ASCE,1978,104(2):1 465-1 488.
[8]陈仁朋,周万欢,曹卫平,等.改进的桩土界面荷载传递双曲线模型及其在单桩负摩阻力时间效应研究中的应用[J].岩土工程学报,2007,29(6):824-830.(CHEN Renpeng,ZHOU Wanhuan,CAOWeiping,et al.Improved hyperbolic model of load-transfer for pile-soil interface and its application in study of negative friction of single piles considering time effect[J].Chinese Journal of Geotechnical Engineering,2007,29(6):824-830.(in Chinese))
[9]曹卫平.桩土界面荷载传递双曲线模型的改进及其应用[J].岩石力学与工程学报,2009,28(1):144-151.(CAO Weiping.An improved load transfer hyperbolic model for pile-soil interface and its application[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(10):144-151.(in Chinese))
[10]WANG B,BOUAZZA A,HABERFILED C.Preliminary observations from laboratory scale model geothermal pile subjected to thermalmechanical loading[C]//Geo-Frontiers Congress.Dallas,Texas:ASCE,2011:488-489.
[11]刘干斌,谢琦峰,范高飞,等.饱和黏土中热交换桩承载力特性模型试验研究[J].岩石力学与工程学报,2017,36(10):2 535-2 543.(LIU Ganbin,XIE Qifeng,FAN Gaofei,et al.Model test on bearing capacity characteristics of heat exchanger piles in saturated clays[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(10):2 535-2 543.(in Chinese))
[12]路宏伟,蒋刚,王昊,等.摩擦型能源桩荷载-温度现场联合测试与承载性状分析[J].岩土工程学报,2017,39(2):334-342.(LUHongwei,JIANG Gang,WANG Hao,et al.In-situ tests and thermomechanical bearing characteristics of friction geothermal energy piles[J].Chinese Journal of Geotechnical Engineering,2017,39(2):334-342.(in Chinese))
[13]ALONSO E E,JOSA A,LEDESMA A.Negative skin friction on piles:A simplified analysis and prediction procedure[J].Geotechnique,1984,34(3):341-357.
[14]赵海丰,桂树强,唐荣彬,等.螺旋型埋管能源桩传热模型的适用性及其试验验证[J].长江科学院院报,2017,34(4):111-116.(ZHAO Haifeng,GUI Shuqiang,TANG Rongbin,et al.Applicability of heat transfer model of energy pile with buried spiral pipe and its experimental verification[J].Journal of Yangtze River Scientific Research Institute,2017,34(4):111-116.(in Chinese))
[15]SURYATRIYASTUTI M E,MROUEH H,BURLON S.A load transfer approach for studying the cyclic behavior of thermo-active piles[J].Computers and Geotechnics,2014,55:378-391.
[16]李维特,黄保海,毕仲波.热应力理论分析及应用[M].北京:中国电力出版社,2004:94-95.(LI Weite,HUANG Baohai,BI Zhongbo.Theoretical analysis and application of thermal stress[M].Beijing:China Electric Power Press,2004:94-95.(in Chinese))
[17]FELLENIUS B H.Results from long-term measurement in piles of drag load and down drag[J].Canadian Geotechnical Journal,2006,43(4):409-430.
[18]SHINICHI Y,MADAN M.Reliability based load transfer characteristics of bored precast piles equipped with ground bulb in the pile toe region[J].Soils and Foundations,2004,44(3):57-68.
[19]中华人民共和国行业标准编写组.建筑桩基技术规范[S].北京:中国建筑工业出版社,1994.(The Professional Standards Compilation Group of People′s Republic of China.Technical code for building pile foundations[S].Beijing:China Architecture and Building Press,1994.(in Chinese))
[20]赵刚,李驰,斯日古楞.温度循环下桩土界面特性及桩侧摩阻力数值模拟[J].防灾减灾工程学报,2017,37(4):546-550.(ZHAOGang,LI Chi,Siriguleng.Friction characteristics of pile-soil interface under temperature cycles and numerical simulation of shaft resistance[J].Journal of Disaster Prevention and Mitigation Engineering,2017,37(4):546-550.(in Chinese))