基于原型桩基的钢管桩压—弯—剪荷载下受力特性的分析研究
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摘要
超长大直径钢管桩由于单桩承载力较高、抗弯能力良好、沉桩工艺简单、对土体扰动小而越来越广泛地应用于跨海大桥的桩基础中。钢管桩由钢管和内填的核心钢筋混凝土组成,其基本原理是利用钢管对核心混凝土产生的套箍约束作用,使核心混凝土处于三向受压状态,从而使核心混凝土具有更高的抗压强度和压缩变形能力,同时钢管也具有较强的承载力,二者结合得到的钢管桩具有较强的刚度。然而关于大直径钢管桩的研究仍十分不足,尤其是考虑承台、群桩效应及土体等因素的影响下钢管桩在压-弯-剪荷载作用下的受力特性基本没有研究资料。
针对这一现状,本文依托港珠澳跨海大桥桩基础工程,结合局部桩基模型试验、原型桩基数值模拟分析及理论计算等方法对比分析在压-弯-剪荷载作用下桩基原型中钢管桩的受力性能,得到以下结论：
(1)钢管桩竖向变形随着轴力增加而线性增大；水平位移随着剪力和弯矩的增大而呈线性增大,并且桩顶水平位移最大、桩端水平位移最小；原型桩基中6根钢管桩竖向变形和水平变形一致,但中桩受力约为角桩的1.3倍；
(2)轴线1处上端纵向压应变随工作荷载增加而增大、下端纵向压应变随工作荷载增加而减小,轴线3处上端纵向压应变随工作荷载增加而减小、下端纵向压应变随工作荷载增加而增大,轴线2处压应变沿桩身分布均匀、随工作荷载增加略微减小；总体上中桩纵向应变比角桩大约9%；
(3)本文中的压-弯-剪荷载作用下钢管应变大于核心混凝土,不符合平截面变形情况；
(4)钢管与核心混凝土应力比沿桩身均匀分布,应力比大小约为6左右,则钢管桩中钢管和核心混凝土的竖向荷载分担比约为1：3；
(5)由于原型桩基是端承式桩基础,中桩与角桩的侧摩阻力分布及大小基本相同；而中桩端阻力大于角桩、第一排桩端阻力大于第二排桩；
(6)局部桩基模型试验中单根钢管桩和原型桩基数值模拟中的中桩和角桩在压-弯-剪荷载作用下的竖向变形、水平变形及各轴线、各截面的纵向应变分布规律均一致,但相同条件下原型桩基中钢管桩的竖向变形、水平变形和纵向应变要小于局部桩基,其变形和应变的变化也更加规律、稳定。
The super-long and large diameter steel pipe piles are widely used in bridge pile foundation, because of the high bearing capacity, good flexural capacity, simple process and small soil disturbance. The steel pipe pile is composed of steel tube and core concrete filling in it. Its basic principle is the confinement effect on the core concrete made by steel tube, so that the core concrete is in the three state compression. The core concrete has high compressive strength and compressive deformation ability, and the steel tube has high carrying capacity, so that the combination of them has strong stiffness. However, research on the large diameter steel pipe pile is still very insufficient, especially the research of steel pipe pile in the pressure-bending-shear loads considering the influence of pile cap, the pile group effect and soil factors.
In view of this situation, this paper relies on the Hong Kong-Zhuhai-Macao Bridge Pile Foundation Engineering, combined with the model test of part foundation, the numerical simulation of prototype pile and calculation analysis to make comparison and analysis of prototype pile's mechanical characteristics in the pressure-bending-shear loads, and obtained the following conclusions:
(1) the vertical deformation increased linearly with the axial force; horizontal displacement increased linearly with the shearing force and moment, and the maximum horizontal displacement is in the top of the pile, the minimum one is in the bottom of pile; the vertical and horizontal deformation of this six steel pipe piles in the foundation are consistent, but the stress of the middle piles are about1.3times than the corner piles;
(2) The compressive strain in axis one increases at the upper and reduce at the bottom with the increase of work load, the compressive strain in axis three is in contrast with axis one, the compressive strain in axis two slightly decreased with the increase of work load; on the whole strain of the middle piles are9%greater than the corner piles;
(3) The compressive strain of steel tubes are greater than the core concrete, it doesn't accord with flat section deformation assumption;
(4) The stress ratio of the steel tube and the core concrete is about6, so that the vertical load ratio of the steel tube and the core concrete is about1:3;
(5) Because the prototype pile foundation is end bearing pile foundation, so that the pile side friction of the middle piles and the corner piles are basically the same; the resistance in the bottom of the middle piles are greater than the corner piles, and the resistance in the first row is greater than the second;
(6) The vertical deformation、horizontal deformation and longitudinal strain of the part pile foundation model test and the prototype pile foundation in the numerical simulation are consistent in the pressure-bending-shear loads. But the deformation and strain in the prototype pile foundation are less and more stable than the one in the part pile foundation.
针对这一现状,本文依托港珠澳跨海大桥桩基础工程,结合局部桩基模型试验、原型桩基数值模拟分析及理论计算等方法对比分析在压-弯-剪荷载作用下桩基原型中钢管桩的受力性能,得到以下结论：
(1)钢管桩竖向变形随着轴力增加而线性增大；水平位移随着剪力和弯矩的增大而呈线性增大,并且桩顶水平位移最大、桩端水平位移最小；原型桩基中6根钢管桩竖向变形和水平变形一致,但中桩受力约为角桩的1.3倍；
(2)轴线1处上端纵向压应变随工作荷载增加而增大、下端纵向压应变随工作荷载增加而减小,轴线3处上端纵向压应变随工作荷载增加而减小、下端纵向压应变随工作荷载增加而增大,轴线2处压应变沿桩身分布均匀、随工作荷载增加略微减小；总体上中桩纵向应变比角桩大约9%；
(3)本文中的压-弯-剪荷载作用下钢管应变大于核心混凝土,不符合平截面变形情况；
(4)钢管与核心混凝土应力比沿桩身均匀分布,应力比大小约为6左右,则钢管桩中钢管和核心混凝土的竖向荷载分担比约为1：3；
(5)由于原型桩基是端承式桩基础,中桩与角桩的侧摩阻力分布及大小基本相同；而中桩端阻力大于角桩、第一排桩端阻力大于第二排桩；
(6)局部桩基模型试验中单根钢管桩和原型桩基数值模拟中的中桩和角桩在压-弯-剪荷载作用下的竖向变形、水平变形及各轴线、各截面的纵向应变分布规律均一致,但相同条件下原型桩基中钢管桩的竖向变形、水平变形和纵向应变要小于局部桩基,其变形和应变的变化也更加规律、稳定。
The super-long and large diameter steel pipe piles are widely used in bridge pile foundation, because of the high bearing capacity, good flexural capacity, simple process and small soil disturbance. The steel pipe pile is composed of steel tube and core concrete filling in it. Its basic principle is the confinement effect on the core concrete made by steel tube, so that the core concrete is in the three state compression. The core concrete has high compressive strength and compressive deformation ability, and the steel tube has high carrying capacity, so that the combination of them has strong stiffness. However, research on the large diameter steel pipe pile is still very insufficient, especially the research of steel pipe pile in the pressure-bending-shear loads considering the influence of pile cap, the pile group effect and soil factors.
In view of this situation, this paper relies on the Hong Kong-Zhuhai-Macao Bridge Pile Foundation Engineering, combined with the model test of part foundation, the numerical simulation of prototype pile and calculation analysis to make comparison and analysis of prototype pile's mechanical characteristics in the pressure-bending-shear loads, and obtained the following conclusions:
(1) the vertical deformation increased linearly with the axial force; horizontal displacement increased linearly with the shearing force and moment, and the maximum horizontal displacement is in the top of the pile, the minimum one is in the bottom of pile; the vertical and horizontal deformation of this six steel pipe piles in the foundation are consistent, but the stress of the middle piles are about1.3times than the corner piles;
(2) The compressive strain in axis one increases at the upper and reduce at the bottom with the increase of work load, the compressive strain in axis three is in contrast with axis one, the compressive strain in axis two slightly decreased with the increase of work load; on the whole strain of the middle piles are9%greater than the corner piles;
(3) The compressive strain of steel tubes are greater than the core concrete, it doesn't accord with flat section deformation assumption;
(4) The stress ratio of the steel tube and the core concrete is about6, so that the vertical load ratio of the steel tube and the core concrete is about1:3;
(5) Because the prototype pile foundation is end bearing pile foundation, so that the pile side friction of the middle piles and the corner piles are basically the same; the resistance in the bottom of the middle piles are greater than the corner piles, and the resistance in the first row is greater than the second;
(6) The vertical deformation、horizontal deformation and longitudinal strain of the part pile foundation model test and the prototype pile foundation in the numerical simulation are consistent in the pressure-bending-shear loads. But the deformation and strain in the prototype pile foundation are less and more stable than the one in the part pile foundation.
引文
[1]杨克已.实用桩基工程[M].北京：人民交通出版社,2004.
[2]阮长青.钢管桩设计中的若干问题探讨[J].地下空间,2003,23(1)：87-89.
[3]中国建筑科学研究院.《建筑桩基技术规范计规范》(JGJ94-94)[S].北京：中国建筑工业出版社,1995.
[4]Jiaqing Yu. An Exploration on the Organizational Structure Design of the Hong Kong-Zhuhai-Macao Bridge Authority :IE&EM 2012,中国湖南长沙,2012[C].
[5]Poulos H. G. Pile Foundation Analysis and Design[M]. Florida:Krieger Publishing,1991.
[6]李学民.开口钢管桩竖向承载力机理及计算探讨[J].桥梁建设,2005,38(4)：28-40.
[7]彭文韬.超长大直径钢管桩竖向承载特性试验分析与预测方法研究[D].武汉理工大学结构工程,2012.
[8]刘长健.洋山三期大型钢管桩试桩及大型钢管桩承载力研究[D].清华大学建设管理系,2008.
[9]王瑞丰.大直径钢管桩水平承载特性研究[D].天津大学岩土工程,2011.
[10]Poulos HG. Analysis of The Settlement of Pile Groups[J]. Geotechnique,1968,18(3):449-471.
[11]Kezdi A. The Bearing CaPaeity of Pile and Pile Group:ICSMFE, London,1957[C].
[12]Cooke R. W. Strains and Displacements around Friction Piles:ICSMF, Moscow,1973[C].
[13]M F RandolPh. Analysis of Deformation of Vertically Loaded Pile[J]. ASCE, 1979,104(12):1465-1488.
[14]Liu Run. Soil Plug Effect Prediction and Pile Driveability Analysis for Large-Diameter Steel Piles in Ocean Engineering[J]. China Ocean Engineering,2009,23(1):107-118.
[15]Bazant Zdenek P. Size Effect in Shear Gailure of Reinforce Concrete[J]. Journal of Engineering Mechanics,1997,12(123):1276-1286.
[16]冷曦晨.大型桥梁桩基承载力试验研究[D].中国地质大学地质工程,2005.
[17]Drivability of Steel Pipe Piles into Diatomaceous Mudstone in the construction of Notojima Brigde: Proc.Int.Symp.ON, San Francisco,1985[C].
[18]史佩栋.实用桩基工程手册[M].北京：中国建筑工业出版社,1999.
[19]中国人民共和国交通部.《港口工程桩基规范》(JTJ254-98)[S].北京：人民交通出版,2002.
[20]陈英琴.海上开口钢管桩荷载传递机理试验研究[D].武汉理工大学结构工程,2010.
[21]汪宏.钢管桩动测试验分析[J].安庆师范学院学报(自然科学版),1999,5(4)：32-36.
[22]刘世安.桩基动测技术研究现状及发展动向[J].资源环境与工程,2005,19(1)：61-64.
[23]Zongwei Deng. Study on monitoring technology of static and dynamic load test pile in situ:The 2nd International Conference on Environmental and Engineering Geophysics,中国湖北武汉,2006[C].
[24]Raushe F. Dynamic Determination of Pile Capacity[J]. ASCE,1985,111(3):367-383.
[25]刘万恩.海上超长大钢管桩的高应变动力检测[J].工程勘察,2006(增刊)：249-252.
[26]董淑海.水下大直径桩的竖向承载特性研究[D].上海交通大学建筑与土木工程,2008.
[27]高明.大型钢管桩水平静动载荷现场试验及桩土相互作用分析[J].水利水运科学研究,1984(1)：1-22.
[28]潘林有.桩的动静态测试方法及存在的问题[J].宁波大学学报(理工版),1998,11(1)：96-99.
[29]龚维明.桩承载力自平衡测试法[J].岩土工程学报,2000,22(5)：532-536.
[30]Guoliang Dai. Application of bi-directional static loading test to deep foundations[J]. Journal of Rock Mechanics and Geotechnical Engineering,2012,4(3):269-275.
[31]李君.自平衡法在大直径钢管桩中的应用与浅析_李君[J].华南港工,2009(1):26-29.
[32]姚丽章.自平衡法测试钢管桩承载力的可靠性探讨_姚丽章[J].华南港工,2008(2)：70-74.
[33]冷曦晨.自平衡法桩基承载力测试中一些问题的探讨[J].地震工程与工程振动,2005,25(2)：160-164.
[34]方鹏飞.超长桩承载性状研究[D].浙江大学岩土工程,2003.
[35]中华人民共和国国家经济贸易委员会.《土工离心模型试验规程》(DL-T 5102-1999)[S].上海科学技术出版社,1999.
[36]何云勇.小直径钢管排桩加固边坡的理论分析与试验验证[D].西南交通大学岩土工程,2012.
[37]黄锋.不同受载方式下桩侧阻的渗水力模型试验研究[J].岩土工程学报,1998,20(2)：10-14.
[38]张振国.垂直受荷桩工作机制渗水力土工模型试验研究[D].清华大学,1990.
[39]端义青.渗水力土工模型试验研究不同长细比单桩荷载传递规律[D].清华大学,1994.
[40]Cohen S Frydman S. Hydraulic gradient models of driven piles in sand[J]. Physical Modelling in Geotechnics-ICPMG-02,2002.
[41]Davisson M. T. Model Study of Laterally Loaded Pile[J]. ASCE,1970,96(5):1605-1627.
[42]徐勋.微型钢管桩组合结构工作机理的模型试验研究[D].成都理工大学岩土工程,2012.
[43]郑俊杰.钢管桩与砂桩多元复合地基室内模型试验[J].华中科技大学学报(自然科学版),2008,36(9)：121-124.
[44]何立明.桩-土-承台非线性共同作用模型试验与数值分析[D].南京工业大学岩土工程,2004.
[45]Yingren Zheng. Strength reduction and step-loading finite element approaches in geotechnical engineering[J]. Journal of Rock Mechanics and Geotechnical Engineering,2009,1(1):21-30.
[46]张明远.基于FLAC-3D的超长大直径钢管桩竖向承载特性模拟[J].岩土力学,2011,32(9)：2856-2860.
[47]赵冉.湛江港大直径钢管桩的压桩试验及其数值模拟[J].水运工程,2013(1)：149-154.
[48]桩基工程手册编委会.桩基工程手册[M].北京：中国建筑工业出版社,1997.
[49]乔孟强.钢管桩承载力竖向性状浅析[J].桥梁工程：160-162.
[50]Y. Kikuchi M. Suzuki Y. Yoshinami. Code Calibration of Designing Open-type Wharf on Vertical Steel Pipe Piles Based on the Partial Factor Approach:ASCE,2006[C].
[51]冈部三郎.桩基计算方法[J].1951,3(25):32-35.
[52]B Broms B. Lateral Resistance of Piles in Cohesive Soils:ASCE,1964[C].
[53]Design of Laterally Loaded Piles:ASCE,1965[C].
[54]曾友金.桩基模型试验研究现状[J].岩十力学,2003,24(增刊)：674-680.
[55]吴国三.岩土工程数值模拟方法的发展_吴国三[J].科技信息,2009(30)：708-709.
[56]费康ABAQUS在岩土工程中的应用[M].中国水利水电出版社,2010.
[57]郑刚.成层土中倾斜荷载作用下桩承载力有限元分析[J].岩土力学,2009,30(3)：680-687.
[58]钱晓丽.大直径桩基极限承载力的计算机模拟与统计分析[D].辽宁工程技术大学岩土工程,2001.
[59]孙训芳.《材料力学》[M].第四版.北京：高等教育出版社,2002.
[2]阮长青.钢管桩设计中的若干问题探讨[J].地下空间,2003,23(1)：87-89.
[3]中国建筑科学研究院.《建筑桩基技术规范计规范》(JGJ94-94)[S].北京：中国建筑工业出版社,1995.
[4]Jiaqing Yu. An Exploration on the Organizational Structure Design of the Hong Kong-Zhuhai-Macao Bridge Authority :IE&EM 2012,中国湖南长沙,2012[C].
[5]Poulos H. G. Pile Foundation Analysis and Design[M]. Florida:Krieger Publishing,1991.
[6]李学民.开口钢管桩竖向承载力机理及计算探讨[J].桥梁建设,2005,38(4)：28-40.
[7]彭文韬.超长大直径钢管桩竖向承载特性试验分析与预测方法研究[D].武汉理工大学结构工程,2012.
[8]刘长健.洋山三期大型钢管桩试桩及大型钢管桩承载力研究[D].清华大学建设管理系,2008.
[9]王瑞丰.大直径钢管桩水平承载特性研究[D].天津大学岩土工程,2011.
[10]Poulos HG. Analysis of The Settlement of Pile Groups[J]. Geotechnique,1968,18(3):449-471.
[11]Kezdi A. The Bearing CaPaeity of Pile and Pile Group:ICSMFE, London,1957[C].
[12]Cooke R. W. Strains and Displacements around Friction Piles:ICSMF, Moscow,1973[C].
[13]M F RandolPh. Analysis of Deformation of Vertically Loaded Pile[J]. ASCE, 1979,104(12):1465-1488.
[14]Liu Run. Soil Plug Effect Prediction and Pile Driveability Analysis for Large-Diameter Steel Piles in Ocean Engineering[J]. China Ocean Engineering,2009,23(1):107-118.
[15]Bazant Zdenek P. Size Effect in Shear Gailure of Reinforce Concrete[J]. Journal of Engineering Mechanics,1997,12(123):1276-1286.
[16]冷曦晨.大型桥梁桩基承载力试验研究[D].中国地质大学地质工程,2005.
[17]Drivability of Steel Pipe Piles into Diatomaceous Mudstone in the construction of Notojima Brigde: Proc.Int.Symp.ON, San Francisco,1985[C].
[18]史佩栋.实用桩基工程手册[M].北京：中国建筑工业出版社,1999.
[19]中国人民共和国交通部.《港口工程桩基规范》(JTJ254-98)[S].北京：人民交通出版,2002.
[20]陈英琴.海上开口钢管桩荷载传递机理试验研究[D].武汉理工大学结构工程,2010.
[21]汪宏.钢管桩动测试验分析[J].安庆师范学院学报(自然科学版),1999,5(4)：32-36.
[22]刘世安.桩基动测技术研究现状及发展动向[J].资源环境与工程,2005,19(1)：61-64.
[23]Zongwei Deng. Study on monitoring technology of static and dynamic load test pile in situ:The 2nd International Conference on Environmental and Engineering Geophysics,中国湖北武汉,2006[C].
[24]Raushe F. Dynamic Determination of Pile Capacity[J]. ASCE,1985,111(3):367-383.
[25]刘万恩.海上超长大钢管桩的高应变动力检测[J].工程勘察,2006(增刊)：249-252.
[26]董淑海.水下大直径桩的竖向承载特性研究[D].上海交通大学建筑与土木工程,2008.
[27]高明.大型钢管桩水平静动载荷现场试验及桩土相互作用分析[J].水利水运科学研究,1984(1)：1-22.
[28]潘林有.桩的动静态测试方法及存在的问题[J].宁波大学学报(理工版),1998,11(1)：96-99.
[29]龚维明.桩承载力自平衡测试法[J].岩土工程学报,2000,22(5)：532-536.
[30]Guoliang Dai. Application of bi-directional static loading test to deep foundations[J]. Journal of Rock Mechanics and Geotechnical Engineering,2012,4(3):269-275.
[31]李君.自平衡法在大直径钢管桩中的应用与浅析_李君[J].华南港工,2009(1):26-29.
[32]姚丽章.自平衡法测试钢管桩承载力的可靠性探讨_姚丽章[J].华南港工,2008(2)：70-74.
[33]冷曦晨.自平衡法桩基承载力测试中一些问题的探讨[J].地震工程与工程振动,2005,25(2)：160-164.
[34]方鹏飞.超长桩承载性状研究[D].浙江大学岩土工程,2003.
[35]中华人民共和国国家经济贸易委员会.《土工离心模型试验规程》(DL-T 5102-1999)[S].上海科学技术出版社,1999.
[36]何云勇.小直径钢管排桩加固边坡的理论分析与试验验证[D].西南交通大学岩土工程,2012.
[37]黄锋.不同受载方式下桩侧阻的渗水力模型试验研究[J].岩土工程学报,1998,20(2)：10-14.
[38]张振国.垂直受荷桩工作机制渗水力土工模型试验研究[D].清华大学,1990.
[39]端义青.渗水力土工模型试验研究不同长细比单桩荷载传递规律[D].清华大学,1994.
[40]Cohen S Frydman S. Hydraulic gradient models of driven piles in sand[J]. Physical Modelling in Geotechnics-ICPMG-02,2002.
[41]Davisson M. T. Model Study of Laterally Loaded Pile[J]. ASCE,1970,96(5):1605-1627.
[42]徐勋.微型钢管桩组合结构工作机理的模型试验研究[D].成都理工大学岩土工程,2012.
[43]郑俊杰.钢管桩与砂桩多元复合地基室内模型试验[J].华中科技大学学报(自然科学版),2008,36(9)：121-124.
[44]何立明.桩-土-承台非线性共同作用模型试验与数值分析[D].南京工业大学岩土工程,2004.
[45]Yingren Zheng. Strength reduction and step-loading finite element approaches in geotechnical engineering[J]. Journal of Rock Mechanics and Geotechnical Engineering,2009,1(1):21-30.
[46]张明远.基于FLAC-3D的超长大直径钢管桩竖向承载特性模拟[J].岩土力学,2011,32(9)：2856-2860.
[47]赵冉.湛江港大直径钢管桩的压桩试验及其数值模拟[J].水运工程,2013(1)：149-154.
[48]桩基工程手册编委会.桩基工程手册[M].北京：中国建筑工业出版社,1997.
[49]乔孟强.钢管桩承载力竖向性状浅析[J].桥梁工程：160-162.
[50]Y. Kikuchi M. Suzuki Y. Yoshinami. Code Calibration of Designing Open-type Wharf on Vertical Steel Pipe Piles Based on the Partial Factor Approach:ASCE,2006[C].
[51]冈部三郎.桩基计算方法[J].1951,3(25):32-35.
[52]B Broms B. Lateral Resistance of Piles in Cohesive Soils:ASCE,1964[C].
[53]Design of Laterally Loaded Piles:ASCE,1965[C].
[54]曾友金.桩基模型试验研究现状[J].岩十力学,2003,24(增刊)：674-680.
[55]吴国三.岩土工程数值模拟方法的发展_吴国三[J].科技信息,2009(30)：708-709.
[56]费康ABAQUS在岩土工程中的应用[M].中国水利水电出版社,2010.
[57]郑刚.成层土中倾斜荷载作用下桩承载力有限元分析[J].岩土力学,2009,30(3)：680-687.
[58]钱晓丽.大直径桩基极限承载力的计算机模拟与统计分析[D].辽宁工程技术大学岩土工程,2001.
[59]孙训芳.《材料力学》[M].第四版.北京：高等教育出版社,2002.