考虑水平摩阻力和大变形的刚性桩网复合地基桩土应力比计算方法
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摘要
为了研究水平摩阻力对加筋垫层挠度和复合地基桩土应力比的影响,以单桩处理范围内的刚性桩网复合地基为研究对象,考虑加筋垫层的大变形效应和三维尺寸效应,运用大挠度薄板理论对加筋垫层荷载传递特性进行分析,建立其挠度控制微分方程,并结合真实边界条件和桩土相互作用,将荷载传递过程分为假定状态和实际状态,运用伽辽金法和功能原理对其挠度进行分步求解.在此基础之上,利用Winkler地基梁理论对桩土应力比进行计算.采用室内足尺试验对计算方法进行验证,并综合分析土体基床系数、桩间距、桩径和界面摩擦刚度等因素对桩土应力比的影响.研究表明:理论计算结果与试验结果较为吻合,桩土应力比随桩间土基床系数和桩径的增大而减小,随桩间距、界面摩擦刚度和桩体基床系数的增大而增大,成果可为工程实践提供参考.
To study the influence of horizontal friction resistance on the deflection of reinforced cushion layer and the stress ratio of pile-soil in composite foundation,the rigid pile-net composite foundation in the effect area of single pile was taken as the research object.Considering the large deflection effect and three-dimensional effect of reinforced cushion,load transfer characteristics were analyzed using large deflection thin plate theory,and the governing differential equation of geogrid flexure deformation was established.Combined with the true three-dimensional boundary conditions and pile-soil interactions,the load transfer process was divided into assumed and actual states.The corresponding solution was deduced by Galerkin method and the principle of function.Based on the deformation of the reinforced cushion layer,the pile-soil stress ratio of rigid pile-net composite foundation was calculated by Winkler foundation beam method.The calculation method was validated by indoor full scale tests.The factors that affect pilesoil stress ratio,such as soil bed coefficient,pile spacing,pile diameter and interface frictional stiffness,were systematically analyzed.It is shown that the analytical solutions show good agreement with the measured data.The pile-soil ratio decreases with the increase of soil bed coefficient and pile diameter,while it increases with the increase of pile spacing,interface friction stiffness and Winkler modulus of pile.The proposed method can be applied in engineering practices.
To study the influence of horizontal friction resistance on the deflection of reinforced cushion layer and the stress ratio of pile-soil in composite foundation,the rigid pile-net composite foundation in the effect area of single pile was taken as the research object.Considering the large deflection effect and three-dimensional effect of reinforced cushion,load transfer characteristics were analyzed using large deflection thin plate theory,and the governing differential equation of geogrid flexure deformation was established.Combined with the true three-dimensional boundary conditions and pile-soil interactions,the load transfer process was divided into assumed and actual states.The corresponding solution was deduced by Galerkin method and the principle of function.Based on the deformation of the reinforced cushion layer,the pile-soil stress ratio of rigid pile-net composite foundation was calculated by Winkler foundation beam method.The calculation method was validated by indoor full scale tests.The factors that affect pilesoil stress ratio,such as soil bed coefficient,pile spacing,pile diameter and interface frictional stiffness,were systematically analyzed.It is shown that the analytical solutions show good agreement with the measured data.The pile-soil ratio decreases with the increase of soil bed coefficient and pile diameter,while it increases with the increase of pile spacing,interface friction stiffness and Winkler modulus of pile.The proposed method can be applied in engineering practices.
引文
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[9]饶为国,江辉煌,侯庆华.桩-网复合地基工后沉降的薄板理论解[J].水利学报,2002(4):23-27.Rao Weiguo,Jiang Huihuang,Hou Qinghua.Deformation of sheet plate due to residual settlement of pile-net composite foundation[J].Journal of Hydraulic Engineering,2002(4):23-27(in Chinese).
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[12]刘鸿文.板壳理论[M].杭州:浙江大学出版社,1987:196-197.Liu Hongwen.Theory of Plates and Shells[M].Hangzhou:Zhejiang University Press,1987:196-197(in Chinese).
[13]闫澍旺,郎瑞卿,孙立强,等.基于薄板理论的刚性桩网复合地基桩土应力比计算[J].岩石力学与工程学报,2017,36(8):2051-2060.Yan Shuwang,Lang Ruiqing,Sun Liqiang,et al.Calculation of pile-soil stress ratio of rigid pile-net composite foundation based on plate theory[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(8):2051-2060(in Chinese).
[14]赵明华,贺炜,曹文贵.基桩负摩阻力计算方法初探[J].岩土力学,2004,25(9):1442-1446.Zhao Minghua,He Wei,Cao Wengui.Study on calculation of negative skin friction resistance on piles[J].Rock and Soil Mechanics,2004,25(9):1442-1446(in Chinese).
[15]谭慧明,刘芝平,丁选明,等.加筋褥垫层对PCC桩复合地基承载特性影响足尺试验研究[J].岩石力学与工程学报,2014(12):2531-2538.Tan Huiming,Liu Zhiping,Ding Xuanming,et al.Full scale model test on effect of reinforced cushion on load transmission behavior of composite foundation of PCC piles[J].Chinese Journal of Rock Mechanics and Engineering,2014(12):2531-2538(in Chinese).
[16]Mylonakis G.Winkler modulus for axially loaded piles[J].Géotechnique,2001,51(5):455-461.
[2]赵明华,张玲,马缤辉.基于文克尔假定的土工格室加筋体受力分析[J].水利学报,2018(6):697-702.Zhao Minghua,Zhang Ling,Ma Binhui.Deformation analysis of geocell reinforcement based on Winkler model[J].Journal of Hydraulic Engineering,2018(6):697-702(in Chinese).
[3]赵明华,张玲,曹文贵,等.基于弹性地基梁理论的土工格室加筋体变形分析[J].岩土力学,2009,30(12):3695-3699.Zhao Minghua,Zhang Ling,Cao Wengui,et al.Deformation analysis of geocell reinforcement based on theory for beam on elastic foundation[J].Rock and Soil Mechanics,2009,30(12):3695-3699(in Chinese).
[4]Zhang Ling,Zhao Minghua,Zou Xiaowei,et al.Analysis of geocell-reinforced mattress with consideration of horizontal-vertical coupling[J].Computers&Geotechnics,2010,37(6):748-756.
[5]张玲.双向增强复合地基承载机理及其设计计算理论研究[D].长沙:湖南大学土木工程学院,2012.Zhang Ling.Working Mechanism of Bidirectional Reinforced Composite Foundation and Its Design Method[D].Changsha:School of Civil Engineering,Hunan University,2012(in Chinese).
[6]马缤辉.土工格室+碎石桩双向增强复合地基承载特性及沉降计算研究[D].长沙:湖南大学土木工程学院,2011.Ma Binhui.The Research on Bearing Characteristic and Settlement of Composite Foundation Bidirectionally Reinforced by Stone Columns and Geocell[D].Changsha:School of Civil Engineering,Hunan University,2011(in Chinese).
[7]赵明华,刘猛,龙军,等.双向增强复合地基土工格室加筋体变形分析[J].中国公路学报,2014,27(5):97-104.Zhao Minghua,Liu Meng,Long Jun,et al.Deformation analysis of geocell-reinforcement in bidirectional reinforced composite foundation[J].China Journal of Highway and Transport,2014,27(5):97-104(in Chinese).
[8]刘猛.“土工格室+碎石桩”复合地基承载特性及变形计算研究[D].长沙:湖南大学土木工程学院,2016.Liu Meng.The Research on Bearing Characteristic and Settlement of Composite Foundation Bidirectionally Re-inforced by Stone Columns and Geocell[D].Changsha:School of Civil Engineering,Hunan University,2011(in Chinese).
[9]饶为国,江辉煌,侯庆华.桩-网复合地基工后沉降的薄板理论解[J].水利学报,2002(4):23-27.Rao Weiguo,Jiang Huihuang,Hou Qinghua.Deformation of sheet plate due to residual settlement of pile-net composite foundation[J].Journal of Hydraulic Engineering,2002(4):23-27(in Chinese).
[10]郑俊杰,张军,马强,等.双向增强体复合地基桩土应力比三维分析[J].华中科技大学学报:自然科学版,2010,38(2):83-86.Zheng Junjie,Zhang Jun,Ma Qiang,et al.Three dimensional analysis of pile-earth stress ratio of biaxial reinforcement composite foundation[J].Journal of Huazhong University of Science and Technology:Natural Science Edition,2010,38(2):83-86(in Chinese).
[11]张军,郑俊杰,马强.路堤荷载下双向增强体复合地基受力机理分析[J].岩土工程学报,2010,28(9):1392-1398.Zhang Jun,Zheng Junjie,Ma Qiang.Mechanical performance of biaxial reinforcement composite foundation under embankment loads[J].Chinese Journal of Geotechnical Engineering,2010,28(9):1392-1398(in Chinese).
[12]刘鸿文.板壳理论[M].杭州:浙江大学出版社,1987:196-197.Liu Hongwen.Theory of Plates and Shells[M].Hangzhou:Zhejiang University Press,1987:196-197(in Chinese).
[13]闫澍旺,郎瑞卿,孙立强,等.基于薄板理论的刚性桩网复合地基桩土应力比计算[J].岩石力学与工程学报,2017,36(8):2051-2060.Yan Shuwang,Lang Ruiqing,Sun Liqiang,et al.Calculation of pile-soil stress ratio of rigid pile-net composite foundation based on plate theory[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(8):2051-2060(in Chinese).
[14]赵明华,贺炜,曹文贵.基桩负摩阻力计算方法初探[J].岩土力学,2004,25(9):1442-1446.Zhao Minghua,He Wei,Cao Wengui.Study on calculation of negative skin friction resistance on piles[J].Rock and Soil Mechanics,2004,25(9):1442-1446(in Chinese).
[15]谭慧明,刘芝平,丁选明,等.加筋褥垫层对PCC桩复合地基承载特性影响足尺试验研究[J].岩石力学与工程学报,2014(12):2531-2538.Tan Huiming,Liu Zhiping,Ding Xuanming,et al.Full scale model test on effect of reinforced cushion on load transmission behavior of composite foundation of PCC piles[J].Chinese Journal of Rock Mechanics and Engineering,2014(12):2531-2538(in Chinese).
[16]Mylonakis G.Winkler modulus for axially loaded piles[J].Géotechnique,2001,51(5):455-461.