考虑侧阻与端阻影响的基桩水平承载力传递矩阵解
|
摘要
为研究桩侧竖向摩阻力、桩端竖向阻力及水平剪应力对基桩水平承载特性的影响,该文首先根据桩侧摩阻力三折线t-s曲线推导得出了附加弯矩-转角本构模型线性解析表达式。随后在四弹簧模型基础上结合该文所提出的桩侧、桩端附加弯矩以及桩端水平剪力本构关系进而建立桩身受力微分方程,并采用Laplace变换解得桩身弹性、塑性段的传递矩阵系数解析解。最后在给出的迭代求解方法基础上进而求得考虑侧阻与端阻影响的基桩水平承载力响应解。通过两组案例对比分析不但验证了该文推导的正确性,也证明了该文所提出的桩侧、桩端附加弯矩以及桩端水平剪力本构模型的合理性;同时结果也表明当地基土体较好、桩径较大时桩侧附加弯矩M_s、桩端附加弯矩Mb和剪力Fb对水平承载特性影响不可忽略。
To investigate the contributions of vertical skin friction, vertical end resistance and horizontal shear stress of pile tip to the lateral bearing capacity of a pile foundation, this work firstly deduces analytical expression of a linear constitutive model characterizing the relationship between additional moment and slope based on the trilinear τ-s curve model of pile shafts. Furthermore, combining the four-type spring model with the presented constitutive relations for additional moment of pile shafts and pile ends, as well as the shear force of pile tip, the differential equations for a pile section is established and the corresponding transfer matrix coefficients for piles in elastic and plastic stage are derived analytically by means of Laplace transformation. Finally, transfer matrix solutions for the lateral behavior of a pile foundation is obtained on the basis of a proposed iterative methodology. The agreement between test data and the calculated results by the proposed method is quite good, which verifies the correctness of the derivation and confirms the rationality of the produced constitutive relations for additional moment of pile shafts, as well as additional moment and shear force of pile tip. Moreover, the comparison also implies that the values of additional moment Ms of pile shafts, additional moment Mb and shear force Fb of pile ends have a significant influence on the lateral load-bearing capacity of piles when large-diameter piles are embedded in stiff materials.
To investigate the contributions of vertical skin friction, vertical end resistance and horizontal shear stress of pile tip to the lateral bearing capacity of a pile foundation, this work firstly deduces analytical expression of a linear constitutive model characterizing the relationship between additional moment and slope based on the trilinear τ-s curve model of pile shafts. Furthermore, combining the four-type spring model with the presented constitutive relations for additional moment of pile shafts and pile ends, as well as the shear force of pile tip, the differential equations for a pile section is established and the corresponding transfer matrix coefficients for piles in elastic and plastic stage are derived analytically by means of Laplace transformation. Finally, transfer matrix solutions for the lateral behavior of a pile foundation is obtained on the basis of a proposed iterative methodology. The agreement between test data and the calculated results by the proposed method is quite good, which verifies the correctness of the derivation and confirms the rationality of the produced constitutive relations for additional moment of pile shafts, as well as additional moment and shear force of pile tip. Moreover, the comparison also implies that the values of additional moment Ms of pile shafts, additional moment Mb and shear force Fb of pile ends have a significant influence on the lateral load-bearing capacity of piles when large-diameter piles are embedded in stiff materials.
引文
[1]Basu D.Analysis of laterally loaded pile in layered soil[D].West Lafayette:Purdue University,2006:10―14.
[2]Dodds A M,Martin G R.Modeling pile behavior in large pile groups under lateral loading[R].Buffalo:Multidisciplinary Center for Earthquake Engineering Research,2007:56―58.
[3]Lam I P,Martin G R.Seismic Design of Highway Bridge Foundations[R].Virginia:Department of Transportation,Federal Highway Administration,1986:44―45.
[4]Mcvay M C,Niraula L.Development of P-Y curves for large diameter piles/drilled shafts in limestone for FBPIER[R].Florida:Civil and Coastal Engineering Dept,University of Florida,2004.
[5]王伯惠,上官兴.中国钻孔灌注桩新发展[M].北京:人民交通出版社,1999:89―90.Wang Bohui,Shangbuan Xing.New development for bored pile in China[M].Beijing:China Communication Press,1999:89―90.(in Chinese)
[6]Ashour M,Helal A.Contribution of vertical skin friction to the lateral resistance of large-diameter shafts[J].Journal of Bridge Engineering,2014,19(2):289―302.
[7]Alikhanlou F.A discrete model for the analysis of short pier foundations in clays[D].Lubbock:Texas Technology University,1981.
[8]Gerolymos N,Gazetas G.Winkler model for lateral response of rigid caisson foundations in linear soil[J].Soil Dynamics and Earthquake Engineering,2006,26(5):347―361.
[9]Varun,Assimaki D,Gazetas G.A simplified model for lateral response of large diameter caisson foundationsLinear elastic formulation[J].Soil Dynamics and Earthquake Engineering,2009,29:268―291.
[10]肖宏彬.竖向荷载作用下大直径桩的荷载传递理论及应用研究[D].长沙:中南大学,2005.Xiao Hongbin.Theoretical and application research on load transfer of vertically loading large diameter piles[D].Changsha:Central South University,2005.(in Chinese)
[11]李灿.大直径钢管桩水平承载特性研究[D].大连:大连理工大学,2012.Li Can.A study on bearing capacity performance of large-diameter monopile foundation under lateral loads[D].Dalian:Dalian University of Technology,2012.(in Chinese)
[12]Gerolymos N,Gazetas G.Static and dynamic response of massive caisson foundations with soil and interface nonlinearities-validation and results[J].Soil Dynamics and Earthquake Engineering,2006,26(5):377-394.
[13]JTG D63―2007,公路桥涵地基与基础设计规范[S].北京:人民交通出版社,2007.JTG D63―2007,Code for design of ground base and foundation of highway bridges and culverts[S].Beijing:China Communication Press,2007.(in Chinese)
[14]Gerolymos N,Gazetas G.Development of Winkler model for static and dynamic response of caisson foundations with soil and interface nonlinearities[J].Soil Dynamics and Earthquake Engineering,2006,26:363―376.
[15]Karapiperis K,Gerolymos N.Combined loading of caisson foundation in cohesive soil:finite element versus Winkler modeling[J].Computers and Geotechnics,2014,56:100―120.
[16]Salgado R.The engineering of foundations[M].New York:Mc Graw-Hill,2008:582―583.
[17]费康.ABAQUS在岩土工程中的应用[M].北京:中国水利水电出版社,2010.Fei Kang.The application of ABAQUS in geotechnical engineering[M].Beijing:China Water&Power Press,2010.(in Chinese)
[18]Zhu M,Zhang Y,Gong W,et al.Generalized solutions for axially and laterally loaded piles in multilayered soil deposits with transfer matrix method[J].International Journal of Geomechanics,2017,17(4):04016104.
[19]竺明星.组合荷载作用下被动桩承载机理研究[D].南京:东南大学,2016.Zhu Mingxing.Research on bearing mechanism of passive pile under combined loads[D].Nanjing:Southeast University,2016.(in Chinese)
[20]竺明星,龚维明,何小元.成层地基土中水平受荷桩桩身响应的矩阵传递解[J].岩土工程学报,2015,37(增刊2):46―50.Zhu Mingxing,Gong Weiming,He Xiaoyuan.Transfer matrix solutions for responses of laterally loaded piles in multilayered soil deposits[J].Chinese Journal of Geotechnical Engineering,2015,37(Suppl 2):46―50.(in Chinese)
[21]王友凯,龚耀清.任意荷载作用下层状横观各向同性弹性地基的直角坐标解[J].工程力学,2006,23(5):9―13.Wang Youkai,Gong Yaoqing.Analytical solution of transversely isotropic elastic multilayered subgrade under arbitrary loading in rectangular coordinates[J].Engineering Mechanics,2016,237(5):9―13.(in Chinese)
[22]Bhushan K,Fong P T,Haley S C.Lateral load tests on drilled piers in stiff clays[J].Journal of the Geotechnical Engineering Division,1979,105(8):969―985.
[23]American Petroleum Institute.Recommended practice for planning,designing and constructing fixed offshore platforms-working stress design[S].Washington:API Recommended Practice 2A-WSD(RP 2AWSD),2000.
[2]Dodds A M,Martin G R.Modeling pile behavior in large pile groups under lateral loading[R].Buffalo:Multidisciplinary Center for Earthquake Engineering Research,2007:56―58.
[3]Lam I P,Martin G R.Seismic Design of Highway Bridge Foundations[R].Virginia:Department of Transportation,Federal Highway Administration,1986:44―45.
[4]Mcvay M C,Niraula L.Development of P-Y curves for large diameter piles/drilled shafts in limestone for FBPIER[R].Florida:Civil and Coastal Engineering Dept,University of Florida,2004.
[5]王伯惠,上官兴.中国钻孔灌注桩新发展[M].北京:人民交通出版社,1999:89―90.Wang Bohui,Shangbuan Xing.New development for bored pile in China[M].Beijing:China Communication Press,1999:89―90.(in Chinese)
[6]Ashour M,Helal A.Contribution of vertical skin friction to the lateral resistance of large-diameter shafts[J].Journal of Bridge Engineering,2014,19(2):289―302.
[7]Alikhanlou F.A discrete model for the analysis of short pier foundations in clays[D].Lubbock:Texas Technology University,1981.
[8]Gerolymos N,Gazetas G.Winkler model for lateral response of rigid caisson foundations in linear soil[J].Soil Dynamics and Earthquake Engineering,2006,26(5):347―361.
[9]Varun,Assimaki D,Gazetas G.A simplified model for lateral response of large diameter caisson foundationsLinear elastic formulation[J].Soil Dynamics and Earthquake Engineering,2009,29:268―291.
[10]肖宏彬.竖向荷载作用下大直径桩的荷载传递理论及应用研究[D].长沙:中南大学,2005.Xiao Hongbin.Theoretical and application research on load transfer of vertically loading large diameter piles[D].Changsha:Central South University,2005.(in Chinese)
[11]李灿.大直径钢管桩水平承载特性研究[D].大连:大连理工大学,2012.Li Can.A study on bearing capacity performance of large-diameter monopile foundation under lateral loads[D].Dalian:Dalian University of Technology,2012.(in Chinese)
[12]Gerolymos N,Gazetas G.Static and dynamic response of massive caisson foundations with soil and interface nonlinearities-validation and results[J].Soil Dynamics and Earthquake Engineering,2006,26(5):377-394.
[13]JTG D63―2007,公路桥涵地基与基础设计规范[S].北京:人民交通出版社,2007.JTG D63―2007,Code for design of ground base and foundation of highway bridges and culverts[S].Beijing:China Communication Press,2007.(in Chinese)
[14]Gerolymos N,Gazetas G.Development of Winkler model for static and dynamic response of caisson foundations with soil and interface nonlinearities[J].Soil Dynamics and Earthquake Engineering,2006,26:363―376.
[15]Karapiperis K,Gerolymos N.Combined loading of caisson foundation in cohesive soil:finite element versus Winkler modeling[J].Computers and Geotechnics,2014,56:100―120.
[16]Salgado R.The engineering of foundations[M].New York:Mc Graw-Hill,2008:582―583.
[17]费康.ABAQUS在岩土工程中的应用[M].北京:中国水利水电出版社,2010.Fei Kang.The application of ABAQUS in geotechnical engineering[M].Beijing:China Water&Power Press,2010.(in Chinese)
[18]Zhu M,Zhang Y,Gong W,et al.Generalized solutions for axially and laterally loaded piles in multilayered soil deposits with transfer matrix method[J].International Journal of Geomechanics,2017,17(4):04016104.
[19]竺明星.组合荷载作用下被动桩承载机理研究[D].南京:东南大学,2016.Zhu Mingxing.Research on bearing mechanism of passive pile under combined loads[D].Nanjing:Southeast University,2016.(in Chinese)
[20]竺明星,龚维明,何小元.成层地基土中水平受荷桩桩身响应的矩阵传递解[J].岩土工程学报,2015,37(增刊2):46―50.Zhu Mingxing,Gong Weiming,He Xiaoyuan.Transfer matrix solutions for responses of laterally loaded piles in multilayered soil deposits[J].Chinese Journal of Geotechnical Engineering,2015,37(Suppl 2):46―50.(in Chinese)
[21]王友凯,龚耀清.任意荷载作用下层状横观各向同性弹性地基的直角坐标解[J].工程力学,2006,23(5):9―13.Wang Youkai,Gong Yaoqing.Analytical solution of transversely isotropic elastic multilayered subgrade under arbitrary loading in rectangular coordinates[J].Engineering Mechanics,2016,237(5):9―13.(in Chinese)
[22]Bhushan K,Fong P T,Haley S C.Lateral load tests on drilled piers in stiff clays[J].Journal of the Geotechnical Engineering Division,1979,105(8):969―985.
[23]American Petroleum Institute.Recommended practice for planning,designing and constructing fixed offshore platforms-working stress design[S].Washington:API Recommended Practice 2A-WSD(RP 2AWSD),2000.