温度效应下黏土-混凝土桩界面直剪试验研究
|
摘要
近年来,地热能源桩的应用越来越广,但在温度效应对桩土接触面力学特性的研究试验较少。文中介绍了一种能考虑温度效应的大型桩土接触面直剪仪,并对在温度、外荷载耦合作用下的黏土-混凝土接触面力学特性进行了直剪试验研究。试验研究表明,在升温时,黏土内部会形成固定的温度梯度,黏土层中的水分会随着该温度梯度的方向进行运移,并且随着法向压力的提升运移效果减弱。随着温度的升高,黏土-混凝土接触面抗剪强度下降,并随着法向压力的增大,抗剪强度下降的幅度降低,温度效应主要通过影响接触面的粘聚力,对摩擦角的影响较小。将干砂-混凝土接触面剪切应力-位移曲线分为"线性段"、"极限段"和"稳定段"。同一法向压力作用下,温度升高时,"线性段"界面剪切应力增速变慢,"极限段"界面剪切应力值变小,"稳定段"界面剪切应力受影响不大。界面升高相同温度梯度时,法向压力大小对最大剪切应力降低值影响相对较小。
In recent years, geothermal energy piles have been used more and more widely, but there are few studies on the mechanical properties of pile-soil interface under temperature effect. A large-scale direct shear apparatus for pile-soil interface is introduced, which can take temperature effect into account. Direct shear tests are carried out on the mechanical properties of soil-concrete interface under the coupling action of temperature and external loads. The experimental results show that a fixed temperature gradient is formed in the clay when the temperature rises, and the water in the clay layer migrates along the direction of the temperature gradient, and the migration effect weakenes with the increase of normal pressure. With the increase of temperature, the shear strength of clayconcrete interface decreases, and with the increase of normal pressure, the decline of shear strength decreases.Temperature effect mainly affects the cohesion of the interface, but has little effect on the friction angle. The dry sand-concrete interface shear stress-displacement curve is divided into "linear segment", "limit segment"and"stability segment". Under the same normal pressure, when the temperature rises, the shear stress increase rate of the"linear section"interface becomes slower, the shear stress value of the"limit section " interface becomes smaller, and the shear stress of the " stability section"interface is less affected. When the interface is raised by the same temperature gradient, the normal pressure has a relatively small effect on the maximum shear stress reduction value.
In recent years, geothermal energy piles have been used more and more widely, but there are few studies on the mechanical properties of pile-soil interface under temperature effect. A large-scale direct shear apparatus for pile-soil interface is introduced, which can take temperature effect into account. Direct shear tests are carried out on the mechanical properties of soil-concrete interface under the coupling action of temperature and external loads. The experimental results show that a fixed temperature gradient is formed in the clay when the temperature rises, and the water in the clay layer migrates along the direction of the temperature gradient, and the migration effect weakenes with the increase of normal pressure. With the increase of temperature, the shear strength of clayconcrete interface decreases, and with the increase of normal pressure, the decline of shear strength decreases.Temperature effect mainly affects the cohesion of the interface, but has little effect on the friction angle. The dry sand-concrete interface shear stress-displacement curve is divided into "linear segment", "limit segment"and"stability segment". Under the same normal pressure, when the temperature rises, the shear stress increase rate of the"linear section"interface becomes slower, the shear stress value of the"limit section " interface becomes smaller, and the shear stress of the " stability section"interface is less affected. When the interface is raised by the same temperature gradient, the normal pressure has a relatively small effect on the maximum shear stress reduction value.
引文
[1]BRANDL H.Energy foundations and other thermo-active ground structures[J].Geotechnique,2006,56(2):81-122.
[2]LIU H L,KONG G Q,NG C W W.Applications of energy piles and technical development of PCC energy piles[J].Chinese Journal of Geotechnical Engineering,2014,36(1):176-181.
[3]LU H W,JIANG G,WANG H,et al.In situ tests and analysis of mechanical-thermo bearing characteristic of drilled friction geothermal energy pile[J].Chinese journal of geotechnical engineering,2017,39(2):334-342.
[4]KRAMER C A,BASU P.Performance of a model geothermal pile in sand[C]//ICPMG-Physical Modelling in Geotechnics,2014.
[5]BOURNER-WEBB P,AMATYA B,SOGA K,et al.Energy pile test at Lambeth College,London:geotechnical and thermodynamic aspects of pile response to heat cycles[J].Geotechnique,2009,59(3):237-248.
[6]LALOUI L,NUTH M,VULLIET L.Experimental and numerical investigations of the behaviour of a heat exchanger pile[J].International journal for numerical&analytical methods in geomechanics,2006,30(8):763-781.
[7]WANG B,BOUAZZA A,HABERFIELD C.Preliminary observations from laboratory scale model geothermal pile subjected to thermal-mechanical loading[C]//Geo-Frontiers Congress,2011:430-439.
[8]MCCARTNEY J S,ROSENBERG J E.Impact of heat exchange on side shear in thermo-active foundations[C]//Geo-Frontiers Congress,2011:488-498.
[9]YAVARI N,TANG A M,PEREIRA J M,et al.Effect of temperature on the shear strength of soils and soil-structure interface[J].Can geotech,2016,53:1186-1194.
[10]LI CH H,KONG G Q,CHE P,et al.Laboratory experimental on interface mechanical properties of energy pile-soil[J].Building energy efficiency,2016,44(3);99-105,114.
[11]ZHAO G,LI C,SI G G L.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):548-553.
[12]DESAI C S.Cyclic Testing and modeling of interfaces[J].Journal of geotechnical engineering,1985,111(6):793-815.
[13]ZHANG G,ZHANG J M.Development and application of cyclic shear apparatus for soil-structure interface[J].Chinese Journal of geotechnical engineering,2003,25(2):149-153.
[14]CAI Z Y,MAO J F,FU H,et al.Development of NHRI-4000 high performance with large contact surface direct shear apparatus[J].Chinesejournalofgeotechnicalengineering,2010,28(9):1319-1322.
[15]ZHAO L Z,YANG P,WANG H B.Development and application of large-scale multi-functional frozen soil-structure interface cycle-shearing system[J].Chinese journal of geotechnical engineering,2013,47(4):707-713.
[16]刘汉龙,孔纲强,吴宏伟.能量桩工程应用研究进展及PCC能量桩技术开发[J].岩土工程学报,2014,36(1):176-181.
[17]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.
[18]李春红,孔纲强,车平,等.能量桩桩-土接触面力学特性室内试验研究[J].建筑节能,2016,44(3):99-105,114.
[19]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):548-553.
[20]张嘎,张建民.大型土与结构接触面循环加载剪切仪的研制及应用[J].岩土工程学报,2003,25(2):149-153.
[21]蔡正银,茅加峰,傅华,等.NHRI-4000型高性能大接触面直剪仪的研制[J].岩土工程学报,2010,28(9):1319-1322.
[22]赵联桢,杨平,王海波.大型多功能冻土-结构接触面循环直剪系统研制及应用[J].岩土工程学报,2013,47(4):707-713.
[2]LIU H L,KONG G Q,NG C W W.Applications of energy piles and technical development of PCC energy piles[J].Chinese Journal of Geotechnical Engineering,2014,36(1):176-181.
[3]LU H W,JIANG G,WANG H,et al.In situ tests and analysis of mechanical-thermo bearing characteristic of drilled friction geothermal energy pile[J].Chinese journal of geotechnical engineering,2017,39(2):334-342.
[4]KRAMER C A,BASU P.Performance of a model geothermal pile in sand[C]//ICPMG-Physical Modelling in Geotechnics,2014.
[5]BOURNER-WEBB P,AMATYA B,SOGA K,et al.Energy pile test at Lambeth College,London:geotechnical and thermodynamic aspects of pile response to heat cycles[J].Geotechnique,2009,59(3):237-248.
[6]LALOUI L,NUTH M,VULLIET L.Experimental and numerical investigations of the behaviour of a heat exchanger pile[J].International journal for numerical&analytical methods in geomechanics,2006,30(8):763-781.
[7]WANG B,BOUAZZA A,HABERFIELD C.Preliminary observations from laboratory scale model geothermal pile subjected to thermal-mechanical loading[C]//Geo-Frontiers Congress,2011:430-439.
[8]MCCARTNEY J S,ROSENBERG J E.Impact of heat exchange on side shear in thermo-active foundations[C]//Geo-Frontiers Congress,2011:488-498.
[9]YAVARI N,TANG A M,PEREIRA J M,et al.Effect of temperature on the shear strength of soils and soil-structure interface[J].Can geotech,2016,53:1186-1194.
[10]LI CH H,KONG G Q,CHE P,et al.Laboratory experimental on interface mechanical properties of energy pile-soil[J].Building energy efficiency,2016,44(3);99-105,114.
[11]ZHAO G,LI C,SI G G L.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):548-553.
[12]DESAI C S.Cyclic Testing and modeling of interfaces[J].Journal of geotechnical engineering,1985,111(6):793-815.
[13]ZHANG G,ZHANG J M.Development and application of cyclic shear apparatus for soil-structure interface[J].Chinese Journal of geotechnical engineering,2003,25(2):149-153.
[14]CAI Z Y,MAO J F,FU H,et al.Development of NHRI-4000 high performance with large contact surface direct shear apparatus[J].Chinesejournalofgeotechnicalengineering,2010,28(9):1319-1322.
[15]ZHAO L Z,YANG P,WANG H B.Development and application of large-scale multi-functional frozen soil-structure interface cycle-shearing system[J].Chinese journal of geotechnical engineering,2013,47(4):707-713.
[16]刘汉龙,孔纲强,吴宏伟.能量桩工程应用研究进展及PCC能量桩技术开发[J].岩土工程学报,2014,36(1):176-181.
[17]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.
[18]李春红,孔纲强,车平,等.能量桩桩-土接触面力学特性室内试验研究[J].建筑节能,2016,44(3):99-105,114.
[19]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):548-553.
[20]张嘎,张建民.大型土与结构接触面循环加载剪切仪的研制及应用[J].岩土工程学报,2003,25(2):149-153.
[21]蔡正银,茅加峰,傅华,等.NHRI-4000型高性能大接触面直剪仪的研制[J].岩土工程学报,2010,28(9):1319-1322.
[22]赵联桢,杨平,王海波.大型多功能冻土-结构接触面循环直剪系统研制及应用[J].岩土工程学报,2013,47(4):707-713.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |