基于桩侧阻力强化效应的嵌岩桩承载力计算
|
摘要
根据常法向刚度条件下结构面剪切力学特性研究嵌岩桩的荷载传递机制。考虑桩–岩界面胶结作用,提出完整的嵌岩桩桩–岩界面剪切机制,即包括胶结破坏、滑动剪胀及剪切滑移3部分;根据桩–岩界面不同剪切阶段的力学特性,建立完整的桩–岩界面剪切本构方程。基于结构面剪切力学特性,从理论上分析嵌岩桩桩侧阻力强化效应的产生机制。研究结果表明,桩侧阻力增强效应在整个桩侧都有发生,但在桩端附近桩侧最为明显。在机制分析的基础上,提出考虑桩侧阻力强化效应的嵌岩桩竖向承载力理论计算方法,该法计算模式明显有别于传统桩基规范算法。工程算例对比分析结果表明,该方法计算值比桩基规范传统算法计算值更接近于现场实测静载试验结果。这一算法可为嵌岩桩设计与应用提供新的思路。
Based on the shear mechanical properties of structural plane under condition of constant normal stiffness,the load transfer mechanism of rock-socketed pile was studied.Considering the bond strength of pile-rock interface,a complete shear mechanism of pile-rock interface of rock-socketed pile was proposed,including bond damage,sliding dilatancy and shear slipping.According to the mechanical properties of pile-rock interface in different shear stages,complete shear constitutive equations for pile-rock interface were put forward.On the basis of shear mechanical properties of pile-rock interface,the enhanced effect of skin friction was analyzed theoretically.The results show that the enhanced effect occurs at the whole pile side and is the most distinct in the vicinity of pile tip.Considering the enhanced effect of skin friction,the theoretical formula for vertical bearing capacity of rock-socketed pile was proposed,which is obviously different from the traditional method suggested by specifications.Comparative analysis of case study shows that the vertical bearing capacity calculated by the proposed method is much closer to the field static load test result than the value calculated by the specifications.It provides a new procedure for design and application of rock-socketed piles.
Based on the shear mechanical properties of structural plane under condition of constant normal stiffness,the load transfer mechanism of rock-socketed pile was studied.Considering the bond strength of pile-rock interface,a complete shear mechanism of pile-rock interface of rock-socketed pile was proposed,including bond damage,sliding dilatancy and shear slipping.According to the mechanical properties of pile-rock interface in different shear stages,complete shear constitutive equations for pile-rock interface were put forward.On the basis of shear mechanical properties of pile-rock interface,the enhanced effect of skin friction was analyzed theoretically.The results show that the enhanced effect occurs at the whole pile side and is the most distinct in the vicinity of pile tip.Considering the enhanced effect of skin friction,the theoretical formula for vertical bearing capacity of rock-socketed pile was proposed,which is obviously different from the traditional method suggested by specifications.Comparative analysis of case study shows that the vertical bearing capacity calculated by the proposed method is much closer to the field static load test result than the value calculated by the specifications.It provides a new procedure for design and application of rock-socketed piles.
引文
[1]吴兴序.桩的端阻和侧摩阻的相互作用及其工程应用价值[J].西南交通大学学报,1997,32(3):313–318.(WU Xingxu.Interactionbetween friction and tip resistance of piles and their significance inconstruction[J].Journal of Southwest Jiaotong University,1997,32(3):313–318.(in Chinese))
[2]刘利民,陈竹昌,李发明.桩侧阻力的强化效应[J].特种结构,1998,15(4):27–29.(LIU Limin,CHEN Zhuchang,LI Faming.Thepile siding resistance strengthening effect[J].Special Structures,1998,15(4):27–29.(in Chinese))
[3]辛公锋,张忠苗,夏唐代,等.高荷载水平下超长桩承载性状试验研究[J].岩石力学与工程学报,2005,24(13):2397–2402.(XINGongfeng,ZHANG Zhongmiao,XIA Tangdai,et al.Experimentalstudy on the bearing behaviors of overlength piles under heavy load[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(13):2 397–2 402.(in Chinese))
[4]黄生根,张晓炜,曹辉.后压浆钻孔灌注桩的荷载传递机制研究[J].岩土力学,2004,25(2):251–254.(HUANG Shenggen,ZHANGXiaowei,CAO Hui.Mechanism study of bored cast-in-place piles withpost-grouting technology[J].Rock and Soil Mechanics,2004,25(2):251–254.(in Chinese))
[5]杜海金,叶洪东,李燕,等.粉喷桩侧摩阻力强化效应分析[J].岩石力学与工程学报,2004,23(22):3775–3779.(DU Haijin,YEHongdong,LI Yan,et al.Analysis of strengthening effect of skinfriction of deep jetting mixing pile[J].Chinese Journal of Rock Mechanicsand Engineering,2004,23(22):3 775–3 779.(in Chinese))
[6]张建新,吴东云.桩端阻力与桩侧阻力相互作用研究[J].岩土力学,2008,29(2):541–544.(ZHANG Jianxin,WU Dongyun.Researchon interaction between resistance at pile and lateral resistance of pile[J].Rock and Soil Mechanics,2008,29(2):541–544.(in Chinese))
[7]蒋建平,高广运,章杨松.桩端岩土强度提高对超长桩桩身总侧阻力的强化效应研究[J].岩土力学,2009,30(9):2609–2615.(JIANG Jianping,GAO Guangyun,ZHANG Yangsong.Strengtheningeffect of total pile lateral friction by improving rock or soil strength atpile tip[J].Rock and Soil Mechanics,2009,30(9):2 609–2 615.(inChinese))
[8]董金荣.灌注桩侧阻力强化弱化效应研究[J].岩土工程学报,2009,31(5):658–662.(DONG Jinrong.Enhanced and weakened effect ofskin friction of cast-in-situ piles[J].Chinese Journal of GeotechnicalEngineering,2009,31(5):658–662.(in Chinese))
[9]JOHNSTON I W,LAM T S K,WILLIAMS A F.Constant normalstiffness direct shear testing for socketed pile design in weak rock[J].Geotechnique,1987,37(1):83–89.
[10]GHAZVINIAN A H,TAGHICHIAN A,HASHEMI M,et al.Theshear behavior of bedding planes of weakness between two differentrock types with high strength difference[J].Rock Mechanics and RockEngineering,2010,43(1):69–87.
[11]SEIDEL J P,HABERFIELD C M.Laboratory testing of concrete-rock joints in constant normal stiffness direct shear[J].GeotechnicalTesting Journal,2002,25(4):391–404.
[12]刘建刚,王建平.嵌岩桩的嵌固效应及载荷试验P-s曲线特征分析[J].工业建筑,1995,25(5):41–44.(LIU Jiangang,WANG Jianping.Analysis for embedding effect of rock-socketed pile and P-s curvefeatures of loading test[J].Industrial Construction,1995,25(5):41–44.(in Chinese))
[13]赵明华,雷勇,刘晓明.基于桩–岩结构面特性的嵌岩桩荷载传递分析[J].岩石力学与工程学报,2009,28(1):103–110.(ZHAOMinghua,LEI Yong,LIU Xiaoming.Analysis of load transfer ofrock-socketed piles based on characteristics of pile-rock structuralplane[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(1):103–110.(in Chinese))
[14]PATTON F D.Multiple modes of shear failure in rock[C]//Proceedingsof the 1st ISRM Congress.[S.l.]:[s.n.],1966:509–513.
[15]史佩栋,梁晋渝.嵌岩桩竖向承载力的研究[J].岩土工程学报,1994,16(4):32–39.(SHI Peidong,LIANG Jinyu.Vertical bearingcapacity of rock-socketed piles[J].Chinese Journal of GeotechnicalEngineering,1994,16(4):32–39.(in Chinese))
[16]中华人民共和国行业标准编写组.JGJ94—2008建筑桩基技术规范[S].北京:中国建筑工业出版社,2008.(The Professional StandardsCompilation Group of People s Republic of China.JGJ 94—2008Technical code for building pile foundation[S].Beijing:China Architectureand Building Press,2008.(in Chinese))
[17]彭柏兴,王星华,雷金山.湘浏盆地红层嵌岩桩荷载传递性状试验研究[J].工程地质学报,2009,17(3):401–407.(PENGBaixing,WANGXinghua,LEI Jinshan.Static loading study of bearing capabilitybehavior of rock-socket pile in red beds soft rock in Xiang—LiouBasin[J].Journal of Engineering Geology,2009,17(3):401–407.(inChinese))
[18]中华人民共和国行业标准编写组.TB10002.5—2005铁路桥涵地基和基础设计规范[S].北京:中国铁道出版社,2005.(The ProfessionalStandards Compilation Group of People s Republic of China.TB10002.5—2005 Code for design on subsoil and foundation of railwaybridge and culvert[S].Beijing:China Railway Publishing House,2005.(in Chinese))
[19]中华人民共和国行业标准编写组.JGJ72—2004高层建筑岩土工程勘察规程[S].北京:中国建筑工业出版社,2004.(The ProfessionalStandards Compilation Group of People s Republic of China.JGJ 72—2004 Specification for geotechnical investigation of tall buildings[S].Beijing:China Architecture and Building Press,2004.(in Chinese))
[2]刘利民,陈竹昌,李发明.桩侧阻力的强化效应[J].特种结构,1998,15(4):27–29.(LIU Limin,CHEN Zhuchang,LI Faming.Thepile siding resistance strengthening effect[J].Special Structures,1998,15(4):27–29.(in Chinese))
[3]辛公锋,张忠苗,夏唐代,等.高荷载水平下超长桩承载性状试验研究[J].岩石力学与工程学报,2005,24(13):2397–2402.(XINGongfeng,ZHANG Zhongmiao,XIA Tangdai,et al.Experimentalstudy on the bearing behaviors of overlength piles under heavy load[J].Chinese Journal of Rock Mechanics and Engineering,2005,24(13):2 397–2 402.(in Chinese))
[4]黄生根,张晓炜,曹辉.后压浆钻孔灌注桩的荷载传递机制研究[J].岩土力学,2004,25(2):251–254.(HUANG Shenggen,ZHANGXiaowei,CAO Hui.Mechanism study of bored cast-in-place piles withpost-grouting technology[J].Rock and Soil Mechanics,2004,25(2):251–254.(in Chinese))
[5]杜海金,叶洪东,李燕,等.粉喷桩侧摩阻力强化效应分析[J].岩石力学与工程学报,2004,23(22):3775–3779.(DU Haijin,YEHongdong,LI Yan,et al.Analysis of strengthening effect of skinfriction of deep jetting mixing pile[J].Chinese Journal of Rock Mechanicsand Engineering,2004,23(22):3 775–3 779.(in Chinese))
[6]张建新,吴东云.桩端阻力与桩侧阻力相互作用研究[J].岩土力学,2008,29(2):541–544.(ZHANG Jianxin,WU Dongyun.Researchon interaction between resistance at pile and lateral resistance of pile[J].Rock and Soil Mechanics,2008,29(2):541–544.(in Chinese))
[7]蒋建平,高广运,章杨松.桩端岩土强度提高对超长桩桩身总侧阻力的强化效应研究[J].岩土力学,2009,30(9):2609–2615.(JIANG Jianping,GAO Guangyun,ZHANG Yangsong.Strengtheningeffect of total pile lateral friction by improving rock or soil strength atpile tip[J].Rock and Soil Mechanics,2009,30(9):2 609–2 615.(inChinese))
[8]董金荣.灌注桩侧阻力强化弱化效应研究[J].岩土工程学报,2009,31(5):658–662.(DONG Jinrong.Enhanced and weakened effect ofskin friction of cast-in-situ piles[J].Chinese Journal of GeotechnicalEngineering,2009,31(5):658–662.(in Chinese))
[9]JOHNSTON I W,LAM T S K,WILLIAMS A F.Constant normalstiffness direct shear testing for socketed pile design in weak rock[J].Geotechnique,1987,37(1):83–89.
[10]GHAZVINIAN A H,TAGHICHIAN A,HASHEMI M,et al.Theshear behavior of bedding planes of weakness between two differentrock types with high strength difference[J].Rock Mechanics and RockEngineering,2010,43(1):69–87.
[11]SEIDEL J P,HABERFIELD C M.Laboratory testing of concrete-rock joints in constant normal stiffness direct shear[J].GeotechnicalTesting Journal,2002,25(4):391–404.
[12]刘建刚,王建平.嵌岩桩的嵌固效应及载荷试验P-s曲线特征分析[J].工业建筑,1995,25(5):41–44.(LIU Jiangang,WANG Jianping.Analysis for embedding effect of rock-socketed pile and P-s curvefeatures of loading test[J].Industrial Construction,1995,25(5):41–44.(in Chinese))
[13]赵明华,雷勇,刘晓明.基于桩–岩结构面特性的嵌岩桩荷载传递分析[J].岩石力学与工程学报,2009,28(1):103–110.(ZHAOMinghua,LEI Yong,LIU Xiaoming.Analysis of load transfer ofrock-socketed piles based on characteristics of pile-rock structuralplane[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(1):103–110.(in Chinese))
[14]PATTON F D.Multiple modes of shear failure in rock[C]//Proceedingsof the 1st ISRM Congress.[S.l.]:[s.n.],1966:509–513.
[15]史佩栋,梁晋渝.嵌岩桩竖向承载力的研究[J].岩土工程学报,1994,16(4):32–39.(SHI Peidong,LIANG Jinyu.Vertical bearingcapacity of rock-socketed piles[J].Chinese Journal of GeotechnicalEngineering,1994,16(4):32–39.(in Chinese))
[16]中华人民共和国行业标准编写组.JGJ94—2008建筑桩基技术规范[S].北京:中国建筑工业出版社,2008.(The Professional StandardsCompilation Group of People s Republic of China.JGJ 94—2008Technical code for building pile foundation[S].Beijing:China Architectureand Building Press,2008.(in Chinese))
[17]彭柏兴,王星华,雷金山.湘浏盆地红层嵌岩桩荷载传递性状试验研究[J].工程地质学报,2009,17(3):401–407.(PENGBaixing,WANGXinghua,LEI Jinshan.Static loading study of bearing capabilitybehavior of rock-socket pile in red beds soft rock in Xiang—LiouBasin[J].Journal of Engineering Geology,2009,17(3):401–407.(inChinese))
[18]中华人民共和国行业标准编写组.TB10002.5—2005铁路桥涵地基和基础设计规范[S].北京:中国铁道出版社,2005.(The ProfessionalStandards Compilation Group of People s Republic of China.TB10002.5—2005 Code for design on subsoil and foundation of railwaybridge and culvert[S].Beijing:China Railway Publishing House,2005.(in Chinese))
[19]中华人民共和国行业标准编写组.JGJ72—2004高层建筑岩土工程勘察规程[S].北京:中国建筑工业出版社,2004.(The ProfessionalStandards Compilation Group of People s Republic of China.JGJ 72—2004 Specification for geotechnical investigation of tall buildings[S].Beijing:China Architecture and Building Press,2004.(in Chinese))