李飞,杨俊杰,宋琦,孙涛

• 1:中国海洋大学海洋环境与生态教育部重点实验室
• 2:中国海洋大学环境科学与工程学院
• 3:山东科技大学地球科学与工程学院

摘要(Abstract)：

利用室内半模试验和颗粒流数值模拟,揭示多层砂土地基扩底桩单桩抗压承载特性及变形特征。结果表明,通过对比分析极限承载力与H_h/D(持力层厚度与扩大头直径之比)的关系可以看出,单桩的抗压极限承载力随H_h/D逐渐增加,当H_h/D超过2.0时,极限承载力基本不再增加,此时的单桩抗压极限承载力稳定在300.01～303.25 N,是H_h/D=0.5时极限承载力(183.83 N)的1.65倍。扩大头下部土体发生局部压缩—剪切破坏,破坏面从扩大头底面边缘向斜下方扩展,在水平方向影响范围达到最大后逐渐向桩内侧收缩;荷载作用越大,地基破坏区域越大,相应的极限抗压承载力也越大;持力层厚度增加,扩大头分担的荷载比例增大,分担的荷载达到稳定需要的桩顶位移也越大,H_h=0.5 D试验扩大头分担的荷载比例稳定时为60%,对应的桩顶位移约为29 mm;桩顶位移达到33 mm后,H_h=1.0～3.0 D试验稳定在63%～65%之间;通过细观颗粒流理论对砂土移动特性的研究发现,持力层厚度从0.5 D增大至2.0 D,破坏面的起始扩展角度从31°增大至42°。数值模拟研究结果与模型试验数据吻合效果良好,证明该方法分析多层砂土地基扩底桩单桩抗压荷载传递机理是可行的。

关键词(KeyWords)： 扩底单桩;竖向承载特性;多层砂土地基;颗粒流

Abstract:

Keywords:

基金项目(Foundation): 国家自然科学基金项目(51779235);国家自然科学基金青年项目(41602322);; 山东科技大学人才引进科研启动基金项目(2015RCJJ010)资助~~

作者(Author): 李飞,杨俊杰,宋琦,孙涛

DOI: 10.16441/j.cnki.hdxb.20190048

参考文献(References)：

• [1] 蒋建平,高广运,顾宝和.扩底桩、楔形桩、等直径桩对比试验研究[J].岩土工程学报,2003(6):764-766.Jiang Jianping,Gao Guangyun,Gu Baohe.Experimental study on comparison of expanded piles,wedge-shaped piles and equal-diameter piles[J].Chinese Journal of Geotechnical Engineering,2003(6):764-766.
• [2] Ayothiraman.Experimental studies on behavior of single pile under combined uplift and lateral loading[J].Journal of Geotechnical andGeoenviron-mental Engineering,2015,141(1):1-10.
• [3] Whitaker T.The Design of Piled Foundations[M].[s.l.]:Pergamon Press,1976.
• [4] 高广运,蒋建平,顾宝和.两种静载试验确定大直径扩底桩竖向承载力[J].地下空间,2003(3):272-276.Gao Guangyun,Jiang Jianping,Gu Baohe.Two static load tests determine the vertical bearing capacity of large diameter bottom Piles[J].Underground Space,2003(3):272-276.
• [5] 孔纲强,顾红伟,车平,等.桩侧截面形式对扩底桩竖向抗压特性影响分析[J].岩土力学,2017(2):361-367.KONG Gang-qiang,GU Hong-wei,CHE Ping,et al.Analysis of influence of pile side section form on vertical compression resistance of expanded pile[J].Rock and Soil Mechanics,2017(2):361-367.
• [6] 李艳婷,顾欢达,殷志文.扩大支盘桩群桩抗拔特性的有限元分析[J].苏州科技学院学报(工程技术版),2013(2):36-40.Li Yanting,Gu Huanda,Yin Zhiwen.Finite element analysis of the uplift characteristics of pile groups with expanded piles[J].Journal of Suzhou University of Science and Technology(Engineering Technology Edition),2013(2):36-40.
• [7] 熊昊,刘润,徐余.抗拔桩承载特性研究与三维数值仿真分析[J].工程地质学报,2013(3):400-407.Xiong Wei,Liu Run,Xu Yu.Research on bearing characteristics of uplift piles and 3D numerical simulation analysis[J].Journal of Engineering Geology,2013(3):400-407.
• [8] DONG ZHANG H X.Algorithms for generating three-dimensional aggregates and asphalt mixture samples by the discrete element method[J].Journal of Computing in Civil Engineering,2013,27(2):111-117.
• [9] 柴浩,郑刚,尹金凤.扩径桩抗压性能的颗粒流数值模拟[J].工业建筑,2007(5):57-60.Chai Hao,Zheng Gang,Yin Jinfeng.Numerical simulation of particle flow of compressive performance of expanded piles[J].Industrial Construction,2007(5):57-60.
• [10] 叶建忠,周健,韩冰.基于离散元理论的静压沉桩过程颗粒流数值模拟[J].岩石力学与工程学报,2007(S1):3058-3064.Ye Jianzhong,Zhou Jian,Han Bing.Numerical simulation of particle flow in static pressure pile sinking process based on discrete element theory[J].Chinese Journal of Rock Mechanics and Engineering,2007(S1):3058-3064.
• [11] 付茹,周博,李小青.基于颗粒离散元的桩侧摩阻力增强效应研究[J].水电能源科学,2015(5):127-131.FU Ru,ZHOU Bo,LI Xiao-qing.Research on enhancement effect of pile side friction resistance based on particle discrete element[J].Hydropower Science,2015(5):127-131.
• [12] 陈亚东,陈思,于艳.长短桩组合桩基宏细观工作性状研究[J].地下空间与工程学报,2015(3):700-705.Chen Yadong,Chen Si,Yu Yan.Research on macroscopic and microscopic working behavior of long-short pile composite pile foundation[J].Chinese Journal of Underground Space and Engineering,2015(3):700-705.
• [13] 许崧,阎长虹,许宝田.砂土地层中桩基受力特征试验分析[J].工程地质学报,2013(4):577-582.XU Wei,YAN Changhong,XU Baotian.Experimental analysis of stress characters of pile found in sand soil[J].Journal of Engineering Geology,2013(4):577-582.
• [14] 向先超,张华,蒋国盛,等.基于颗粒流的抗滑桩土拱效应研究[J].岩土工程学报,2011(3):386-391.Xiang Xianchao,Zhang Hua,Jiang Guosheng,et al.Study on soil arching effect of anti-slide pile based on particle flow[J].Chinese Journal of Geotechnical Engineering,2011(3):386-391.
• [15] 马哲,吴承霞,肖昭然.静压桩端阻力和侧阻力的颗粒流数值模拟[J].中国矿业大学学报,2010(4):622-626.Ma Zhe,Wu Chengxia,Xiao Zhaoran.Numerical simulation of particle flow in static pressure pile side resistance and side resistance[J].Journal of China University of Mining & Technology,2010(4):622-626.
• [16] 刘文白,刘兹胜,周健.砂土中等截面桩的上拔机制分析[J].岩土力学,2009(S1):201-205.LIU Wen-bai,LIU Zi-sheng,ZHOU Jian.Analysis of uplift mechanism of medium-section piles in sand[J].Rock and Soil Mechanics,2009(S1):201-205.
• [17] 郑刚,焦莹,柴浩,等.扩径桩抗压抗拔性能的颗粒流数值模拟[J].天津大学学报,2008(1):78-84.ZHENG Gang,JIAO Ying,CHAI Hao,et al.Numerical simulation of particle flow in compressive and pull-out performance of expanded piles[J].Journal of Tianjin University,2008(1):78-84.
• [18] Scherfler.Modeling of cutting tool soil interaction part II[J].Macromechanical Model and Upscaling,2005,36(5):343-359.
• [19] Wiuiam Powrie.Numerical modeling of plane strain tests on sands using a particulate approach[J].Geotechnique,2005,55(4):297-306.
• [20] GEO.Foundation Design and Construction[M].[s.l.]:Geotechnical Engineering Office,2006.
• [21] EN B.Geotechnical Design-Part 1:General Rules[M].British:British Standards Institution,2004.
• [22] 朱洪昌,徐金明,黄大勇.考虑成层土分布和试桩结果的桩土相互作用细观特征研究[J].水文地质工程地质,2016(3):106-112.Zhu Hongchang,Xu Jinming,Huang Dayong.Microscopic characteristics of pile-soil interaction considering layered soil distribution and test pile results[J].Hydrogeology and Engineering Geology,2016(3):106-112.
• [23] 周健,邓益兵,叶建忠,等.砂土中静压桩沉桩过程试验研究与颗粒流模拟[J].岩土工程学报,2009(4):501-507.ZHOU Jian,DENG Yi-bing,YE Jian-zhong,et al.Experimental study and particle flow simulation of static piles in sandy soils[J].Chinese Journal of Geotechnical Engineering,2009(4):501-507.
• [24] 周健,郭建军,张昭,等.砂土中单桩静载室内模型试验及颗粒流数值模拟[J].岩土力学,2010(6):1763-1768.ZHOU Jian,GUO Jian-jun,ZHANG Zhao,et al.Model test of single pile static load in sand and numerical simulation of particle flow[J].Rock and Soil Mechanics,2010(6):1763-1768.
• [25] 王浩,周健,邓志辉.砂土中桩端阻力随位移发挥的内在机理研究[J].岩土工程学报,2006(5):587-593.WANG Hao,ZHOU Jian,DENG Zhihui.Intrinsic mechanism of pile end resistance with displacement in sand[J].Chinese Journal of Geotechnical Engineering,2006(5):587-593.
• [26] 宋琦,杨俊杰,孙涛,等.扩底抗拔桩动态变形全过程承载特性模型试验研究[J].中国海洋大学学报(自然科学版),2018,52(3):2022.Song Q,Yang J J,Sun T,et al.Model tests on bearing behavior of dynamic deformation process of uplift piles with enlarged base[J].Periodical of Ocean University of China,2018,52(3):2022.
• [27] 楊俊傑,豊澤康男.遠心力載荷装置を用いた補強砂地盤の支持力実験[J].土と基礎,2003(51):47-49.YANG Junjie,Toyosawa Yasuo.Bearing capacity of reinforced sandy ground using centrifuge tests[J].Soil Mechanics and Foundation Engineering,2003,51:47-49.
• [28] 马险峰,孔令刚,方薇,等.砂雨法试样制备平行试验研究[J].岩土工程学报,2014(10):1791-1801.Ma Xianfeng,Kong Linggang,Fang Wei,et al.Parallel test study on sample preparation by sand rain method[J].Chinese Journal of Geotechnical Engineering,2014(10):1791-1801.
• [29] Bhandri A H J W F.DEM analysis of stresses and deformations of geogrid-reinforced embank-ments over piles[J].International Journal of Geomechanics,2014,12(4):340-350.
• [30] 石崇.颗粒流数值模拟技巧与实践[M].第一版.北京:中国建筑工业出版社,2015.Shi Chong.Numerical Simulation Skills and Practice of Particle Flow[M].First Edition.Beijing:China Building Industry Press,2015.
• [31] Wang Z R A.A new suggestion for determining 2D porosities in DEM studies[J].Geomechanics and Engineering,2014,6(7):665-678.
• [32] 姜光成,胡乃联,林成浩,等.岩体力学参数确定的GA-FLAC～(3D)位移反演方法[J].金属矿山,2017(11):37-41.JIANG Guang-cheng,HU Nai-lian,LIN Cheng-hao,et al.GA-FLAC～(3D) displacement inversion method for determining rock mechanics parameters[J].Metal Mine,2017(11):37-41.
• [33] J Y,H O.A study on bearing capacity of geogrid-reinforced foundation ground[J].Proceedings of Geotextile Symposium,1991(6):15-23.

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