黏性土中开口与闭口模型管桩受力性状试验研究
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摘要
为研究开口和闭口试桩在黏性土体静力沉桩过程中荷载传递规律及承载性能的差异性,采用桩身开槽预埋增敏微型光纤光栅传感器的方法,针对黏性地基土,开展两组不同桩端形式模型试桩承载性能对比试验,测得沉桩过程中压桩力、桩端阻力、桩侧摩阻力及桩身轴力发展变化规律。结果表明:光纤光栅传感器可实时监测沉桩过程中桩身受力状态;开口和闭口模型管桩的压桩力、桩端阻力等荷载均随着沉桩深度的增加呈增长趋势,而不同贯入深度下的桩身轴力却逐渐递减;黏性土中的静力压桩、开口管桩和闭口管桩的桩端阻力占比均超过50%;在桩侧摩阻力发挥上,双壁开口模型管桩外管是内管的3倍。当开口管桩贯入深度达到最大值90cm时,土塞高度稳定在33cm,此时,桩侧单位侧摩阻力的分布呈下大上小的形式。
In order to study the load transfer pattern and the bearing capacity difference between the open test pile and the closed test pile in the static pile sinking process in the cohesive soil,the method of preembedded sensitized micro-fiber grating sensor is adopted in this paper.In the foundation soil,a comparison test of the bearing capacity of the test piles in different pile end models was carried out.The variation of pile force,pile end resistance,pile side friction resistance and pile axial force was measured.The testing results show that the fiber Bragg grating sensor can monitor the pile body stress state in the pile sinking process in real time;the pile bearing capacity and pile end resistance of the open and closed model pipe piles all increase with pile depth,with differentmagnitudes.The axial force of the pile under the depth is gradually decreasing;the ratio of the pile end resistance of the open pipe pile and the closed pipe pile is more than 50%;the double-walled open-ended model pipe pile is used for the pile side friction resistance,of which the outer tube is 3 times as much as the inner tube..When the penetration depth of the open pipe pile reaches a maximum of 90 cm,the height of the soil plug is stable at 33 cm.Consequently,the distribution of the side frictional resistance of the pile side increase from the top to the bottom.
In order to study the load transfer pattern and the bearing capacity difference between the open test pile and the closed test pile in the static pile sinking process in the cohesive soil,the method of preembedded sensitized micro-fiber grating sensor is adopted in this paper.In the foundation soil,a comparison test of the bearing capacity of the test piles in different pile end models was carried out.The variation of pile force,pile end resistance,pile side friction resistance and pile axial force was measured.The testing results show that the fiber Bragg grating sensor can monitor the pile body stress state in the pile sinking process in real time;the pile bearing capacity and pile end resistance of the open and closed model pipe piles all increase with pile depth,with differentmagnitudes.The axial force of the pile under the depth is gradually decreasing;the ratio of the pile end resistance of the open pipe pile and the closed pipe pile is more than 50%;the double-walled open-ended model pipe pile is used for the pile side friction resistance,of which the outer tube is 3 times as much as the inner tube..When the penetration depth of the open pipe pile reaches a maximum of 90 cm,the height of the soil plug is stable at 33 cm.Consequently,the distribution of the side frictional resistance of the pile side increase from the top to the bottom.
引文
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[13]寇海磊，张明义，刘俊伟．基于光纤传感技术静压桩承载力时效性机理分析[J]．岩土力学，2013,34(4):1082-1088.KOU H L,ZHANG M Y,LIU J W.Analysis of timedependent mechanism of bearing capacity of static pressed pile based on optical fiber sensing technology[J]. Rock and Soil Mechanics,2013,34(4):1082-1088.
[14]CHAN T H T,YU L,TAM H Y,et al.Fiber bragg grating sensors for structural health monitoring of Tsing Ma bridge:Background and experimental observation[J].Engineering Structures,2006,28(5):648-659.
[15]土工试验方法标准：GB/T 50123—1999[S]．北京：中国计划出版社，1999.Geotechnical test method standards:GB/T 50123-1999[S].Beijing:China Planning Press,1999.
[16]建筑桩基技术规范：JGJ 94—2008[S]．北京：中国建筑工业出版社，2008.Technical Specifications for Building Pile Foundation:JGJ 94-2008[S].Beijing:China Architecture&Building Press,2008.
[17]张涛．地下结构振动台试验刚性模型箱边界效应研究[D]．成都：西南交通大学，2018.ZHANG T.Study on boundary effect of rigid model box for shaking table test of underground structure[D].Chengdu:Southwest Jiaotong University,2018.
[18]LEHANE B M,GAVIN K G.Base resistance of jacked pipe piles in sand[J].Journal of Geotechnical and Geoenvironmental Engineering, 2001, 127(6):473-480.
[19]YASUFUKU N,OCHIAI H,OHNO S.Pile endbearing capacity of sand related to soil compressibility[J].Soils and Foundations,2001,41(4):59-71.
[20]COOKE R W,PRICE G,TARR K.Jacked piles in London Clay:a study of load transfer and settlement under working conditions[J].Géotechnique,1979,29(2):113-147.
[21]李雨浓，李镜培，赵仲芳，等．基于静力触探试验的静压桩沉桩阻力估算[J]．路基工程，2010(3):67-69.LI Y N,LI J P,ZHAO Z F,et al.Estimation of resistance of static pressure pile sinking based on cone penetration test[J].Subgrade Engineering,2010(3):67-69.(in Chinese)
[22]储王应，王能民．静力压桩沉桩阻力分析与估算[J]．岩土工程技术，2000,14(1):25-28.CHU W Y,WANG N M.Analysis and estimation of resistance of piles in static piles[J].Geotechnical Engineering Technology,2000,14(1):25-28,46.(in Chinese)
[23]董光辉，张明义，杨敏，等．考虑侧阻退化的静压桩沉桩阻力的计算公式及工程应用[J]．结构工程师，2008,24(3):113-116,125.DONG G H,ZHANG M Y,YANG M,et al.Study on penetration resistance of jacked piles considering friction fatigue[J].Structural Engineers,2008,24(3):113-116,125.(in Chinese)
[2]MURTHY D S,ROBINSON R G,RAJAGOPAL K.Formation of soil plug in open-ended pipe piles in sandy soils[J]. International Journal of Geotechnical Engineering,2018:1-11.
[3]张明义，邓安福．预制桩静力贯入层状地基的试验研究[J]．岩土工程学报，2000,22(4):490-492.ZHANG M Y,DENG A F.Experimental study on static penetration of prefabricated pile into layered soil[J].Chinese Journal of Geotechnical Engineering,2000,22(4):490-492.(in Chinese)
[4]马海龙．开口桩与闭口桩承载力时效的试验研究[J]．岩石力学与工程学报，2008,27(Sup2):3349-3353.MA H L.Field test on time effect of bearing capacity on end-open pile and end-closed pile[J].Chinese Journal of Rock Mechanics and Engineering,2008,27(Sup2):3349-3353.(in Chinese)
[5]PAIK K,SALGADO R.Determination of bearing capacity of open-ended piles in sand[J].Journal of Geotechnical and Geoenvironmental Engineering,2003,129(1):46-57.
[6]刘锟，赵春风．不同桩端土承压钻孔灌注桩模型试验研究[J]．岩土工程学报，2011,33(3):490-495.LIU K,ZHAO C F.Model test study of bored piles under different pile end soils[J].Chinese Journal of Geotechnical Engineering,2011,33(3):490-495.(in Chinese)
[7]李镜培，操小兵，李林，等．静压沉桩与CPTU贯入离心模型试验及机制研究[J]．岩土力学，2018,39(12):4305-4312.LI J P,CAO X B,LI L,et al.Centrifugal model test and mechanism study of jacked pile and CPTU penetration[J].Rock and Soil Mechanics,2018,39(12):4305-4312.(in Chinese)
[8]刘清秉，项伟，LEHANE B M，等．颗粒形状对砂土抗剪强度及桩端阻力影响机制试验研究[J]．岩石力学与工程学报，2011,30(2):400-410.LIU Q B, XIANG W, LEHANE B M,et al.Experimental study of effect of particle shapes on shear strength of sand and tip resistance of driven piles[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(2):400-410.(in Chinese)
[9]蒋跃楠，黄广龙．砂土中静压桩的桩端作用效应分析[J]．建筑科学，2016,32(11):74-82.JIANG Y N,HUANG G L.Analysis of the effect of pile ends in static pressure piles in sand[J].Journal of Building Science,2016,32(11):74-82.(in Chinese)
[10]李雨浓，李镜培，赵仲芳，等．层状地基静压桩贯入过程机理试验[J]．吉林大学学报（地球科学版），2010,40(6):1409-1414.LI Y N,LI J P,ZHAO Z F,et al.Model test research on penetration process of jacked pile in layered soil[J].Journal of Jilin University(Earth Science Edition),2010,40(6):1409-1414.(in Chinese)
[11]钱峰，刘干斌，齐昌广，等．饱和黏土中静压沉桩模型试验及数值模拟研究[J]．水文地质工程地质，2016,43(5):56-61,69.QIAN F,LIU G B,QI C G,et al.Static pressure pilesinking model tests and numerical simulation on saturated clay[J]. Hydrogeology and Engineering Geology,2016,43(5):56-61,69.(in Chinese)
[12]鲁嘉，喻军，陈金祥，等．砂土中成桩工艺对桩基承载性能影响的室内模型试验研究[J]．岩石力学与工程学报，2012,31(5):1055-1063.LU J,YU J,CHEN J X.Laboratory model test research on influence of piling techniques on bearing performance of pile foundations in sand[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(5):1055-1063.(in Chinese)
[13]寇海磊，张明义，刘俊伟．基于光纤传感技术静压桩承载力时效性机理分析[J]．岩土力学，2013,34(4):1082-1088.KOU H L,ZHANG M Y,LIU J W.Analysis of timedependent mechanism of bearing capacity of static pressed pile based on optical fiber sensing technology[J]. Rock and Soil Mechanics,2013,34(4):1082-1088.
[14]CHAN T H T,YU L,TAM H Y,et al.Fiber bragg grating sensors for structural health monitoring of Tsing Ma bridge:Background and experimental observation[J].Engineering Structures,2006,28(5):648-659.
[15]土工试验方法标准：GB/T 50123—1999[S]．北京：中国计划出版社，1999.Geotechnical test method standards:GB/T 50123-1999[S].Beijing:China Planning Press,1999.
[16]建筑桩基技术规范：JGJ 94—2008[S]．北京：中国建筑工业出版社，2008.Technical Specifications for Building Pile Foundation:JGJ 94-2008[S].Beijing:China Architecture&Building Press,2008.
[17]张涛．地下结构振动台试验刚性模型箱边界效应研究[D]．成都：西南交通大学，2018.ZHANG T.Study on boundary effect of rigid model box for shaking table test of underground structure[D].Chengdu:Southwest Jiaotong University,2018.
[18]LEHANE B M,GAVIN K G.Base resistance of jacked pipe piles in sand[J].Journal of Geotechnical and Geoenvironmental Engineering, 2001, 127(6):473-480.
[19]YASUFUKU N,OCHIAI H,OHNO S.Pile endbearing capacity of sand related to soil compressibility[J].Soils and Foundations,2001,41(4):59-71.
[20]COOKE R W,PRICE G,TARR K.Jacked piles in London Clay:a study of load transfer and settlement under working conditions[J].Géotechnique,1979,29(2):113-147.
[21]李雨浓，李镜培，赵仲芳，等．基于静力触探试验的静压桩沉桩阻力估算[J]．路基工程，2010(3):67-69.LI Y N,LI J P,ZHAO Z F,et al.Estimation of resistance of static pressure pile sinking based on cone penetration test[J].Subgrade Engineering,2010(3):67-69.(in Chinese)
[22]储王应，王能民．静力压桩沉桩阻力分析与估算[J]．岩土工程技术，2000,14(1):25-28.CHU W Y,WANG N M.Analysis and estimation of resistance of piles in static piles[J].Geotechnical Engineering Technology,2000,14(1):25-28,46.(in Chinese)
[23]董光辉，张明义，杨敏，等．考虑侧阻退化的静压桩沉桩阻力的计算公式及工程应用[J]．结构工程师，2008,24(3):113-116,125.DONG G H,ZHANG M Y,YANG M,et al.Study on penetration resistance of jacked piles considering friction fatigue[J].Structural Engineers,2008,24(3):113-116,125.(in Chinese)