Numerical Simulation of Particle Flow Characteristics of Jacked Pile Penetration in Laminated Clay Soil
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摘要:
为深入探讨层状黏性土中静压桩的贯入机制,结合离散元PFC2D软件在处理大变形、非线性等问题的优势,考虑到接触黏结模型对模拟土体的优越性,建立了静压桩贯入层状黏土中的离散元模型,实现了离散元中静压桩的贯入过程;探讨了静压桩贯入过程中压桩力、桩端阻力、桩侧摩阻力以及桩侧径向压力随贯入深度的变化规律,从细观层次上分析了不同桩径的静压桩贯入层状土中土体接触力链的分布特征,明确了沉桩过程中土体位移的变化规律. 试验结果表明:随着桩径的增大,土层的变化对压桩力的影响逐渐减小;桩侧摩阻力和桩侧径向土压力的变化规律相似,在同一贯入深度处均出现明显的退化现象;不同土层接触力链的表现形式不同,桩端位于粉质黏土层时,桩端的影响范围约为7
D (D 为桩径),桩端位于粉土层时,桩端的影响范围约为9D ;粉质黏土中土颗粒主要以径向位移为主,而在粉土层中土颗粒位移受其上下土层的软硬程度制约.Abstract:To investigate the penetration mechanism of jacked piles in laminated clay and utilize the advantages of discrete element PFC2D software in dealing with large deformation and nonlinearity, given that the contact bonding model excels in soil simulation, a discrete element model for jacked pile penetration in laminated clay is established. The penetration process of jacked piles is realized in discrete element software. It is explored about how the pile force, pile end resistance, friction resistance and radial pressure at pile sides change with penetration depth in jacked pile penetration. The distribution characteristics of soil contact force chain are analyzed in the microscopic level for jacked pile penetration of different pile diameters. The variation law of soil displacement in jacking process is clarified. The test results show that, with the increase in pile diameter, the influence of soil layer on pile pressure decreases gradually. The friction resistance and radial earth pressure at pile sides are similar, and there is obvious degeneration at the given depth. Soil layers vary in the forms of contact force chains. When the pile end is located in the silty clay, the influence range of the pile end is about 7
D (D is pile diameter); when the pile end is located in the silty soil, it is about 9D . The clay particles in silty clay mainly show radial displacement. The displacement of soil particles in the silty soil is restricted by the hardness of the upper and lower soil layers.-
Key words:
- PFC2D /
- numerical simulation /
- jacked pile /
- laminated clay soil
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表 1 土层细观参数
Table 1. Soil microscopic parameters
土层 土层名称 土层厚度/
cm密度/
(kg•m−3)法向接触刚度/
(×107 N•m−1)切向接触刚度/
(×107 N•m−1)法向黏结强度/N 切向黏结强度/N 摩擦系数 1 回填土(深黄色) 5 2720 1 1 500 250 0.270 2 粉土(深红色) 5 2710 5 5 500 250 0.756 3 粉质黏土(深蓝色) 5 2720 1 1 1000 500 0.320 4 粉质黏土(深棕色) 5 2720 1 1 1000 500 0.460 5 粉土(深灰色) 5 2710 5 5 500 250 0.790 6 粉质黏土(绿色) 5 2720 1 1 1000 500 0.502 7 粉土(黑色) 5 2710 5 5 500 250 0.780 8~12 砂土(橙色、紫色、青色、浅灰色、浅黄色) 25 2650 80 80 0.500 -
[1] CHOPRA M B, DARGUSH G F. Finite-element analysis of time-dependent large-deformation pro- blems[J]. International Journal for Numerical and Analytical Methods in Geomechanics, 1992, 16(2): 101-130. [2] VAN BAARS S, VAN NIEKERK W J. Numerical modelling of tension piles[M]//Beyond 2000 in Computational Geotechnics. [S.l.]: Routledge, 2019: 237-246. [3] 张明义,邓安福,干腾君. 静力压桩数值模拟的位移贯入法[J]. 岩土力学,2003,24(1): 113-117. doi: 10.3969/j.issn.1000-7598.2003.01.020ZHANG Mingyi, DENG Anfu, GAN Tengjun. Displacement penetration method used for numerical simulation to jacked pile[J]. Rock and Soil Mechanics, 2003, 24(1): 113-117. doi: 10.3969/j.issn.1000-7598.2003.01.020 [4] 鹿群,龚晓南,崔武文,等. 饱和成层地基中静压单桩挤土效应的有限元模拟[J]. 岩土力学,2008,29(11): 3017-3020. doi: 10.3969/j.issn.1000-7598.2008.11.022LU Qun, GONG Xiaonan, CUI Wuwen, et al. Squeezing effects of jacked pile in layered soil[J]. Rock and Soil Mechanics, 2008, 29(11): 3017-3020. doi: 10.3969/j.issn.1000-7598.2008.11.022 [5] 寇海磊,张明义,张吉坤. 层状粘性土及砂土地基中静力压桩连续贯入的数值模拟[J]. 工程力学,2012,29(12): 175-181. doi: 10.6052/j.issn.1000-4750.2011.04.0252KOU Hailei, ZHANG Mingyi, ZHANG Jikun. Numerical simulation of the successive penetration of jacked pile in layered cohesive soil and sand[J]. Engineering Mechanics, 2012, 29(12): 175-181. doi: 10.6052/j.issn.1000-4750.2011.04.0252 [6] 雷华阳,李肖,陆培毅,等. 管桩挤土效应的现场试验和数值模拟[J]. 岩土力学,2012,33(4): 1006-1012. doi: 10.3969/j.issn.1000-7598.2012.04.007LEI Huayang, LI Xiao, LU Peiyi, et al. Field test and numerical simulation of squeezing effect of pipe pile[J]. Rock and Soil Mechanics, 2012, 33(4): 1006-1012. doi: 10.3969/j.issn.1000-7598.2012.04.007 [7] 马哲,吴承霞,肖昭然. 静压桩在砂土沉桩过程中桩周土应力-位移场变化规律的颗粒流数值模拟[J]. 建筑结构,2009,39(9): 117-120.MA Zhe, WU Chengxia, XIAO Zhaoran. Numerical simulation of particle flow code for stress-displacement field to jacked pile down in sand soil[J]. Building Structure, 2009, 39(9): 117-120. [8] LI L C, WU W B, HESHAM EL NAGGAR M, et al. DEM analysis of the sand plug behavior during the installation process of open-ended pile[J]. Computers and Geotechnics, 2019, 109: 23-33. doi: 10.1016/j.compgeo.2019.01.014 [9] 雷华阳,李宸元,刘景锦,等. 交替式真空预压法加固吹填超软土试验及数值模拟研究[J]. 岩石力学与工程学报,2019,38(10): 2112-2125.LEI Huayang, LI Chenyuan, LIU Jingjin, et al. Experimental study and numerical simulation of an alternating vacuum preloading method for strengthening hydraulic fill super soft soils[J]. Chinese Journal of Rock Mechanics and Engineering, 2019, 38(10): 2112-2125. [10] 蒋明镜,付昌,刘静德,等. 不同沉积方向各向异性结构性砂土离散元力学特性分析[J]. 岩土工程学报,2016,38(1): 138-146. doi: 10.11779/CJGE201601015JIANG Mingjing, FU Chang, LIU Jingde, et al. DEM simulations of anisotropic structured sand with different deposit directions[J]. Chinese Journal of Geotechnical Engineering, 2016, 38(1): 138-146. doi: 10.11779/CJGE201601015 [11] 孔亮,苏强,王燕昌,等. 慢速往复荷载下砂土的细观力学与耗能机理探讨[J]. 地下空间与工程学报,2012,8(2): 268-273,300.KONG Liang, SU Qiang, WANG Yanchang, et al. Mesoscopic mechanics and energy dissipation analysis of sand deformation under slow cyclic loading[J]. Chinese Journal of Underground Space and Engineering, 2012, 8(2): 268-273,300. [12] ESPOSITO R G, VELLOSO R Q, VARGAS JR E, et al. Multi-scale sensitivity analysis of pile installation using DEM[J]. Computational Particle Mechanics, 2018, 5(3): 375-386. doi: 10.1007/s40571-017-0175-2 [13] JIANG M J, DAI Y S, CUI L, et al. Investigating mechanism of inclined CPT in granular ground using DEM[J]. Granular Matter, 2014, 16(5): 785-796. doi: 10.1007/s10035-014-0508-2 [14] 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,2010,39(4): 622-626.MA Zhe, WU Chengxia, XIAO Zhaoran. Numerical simulation of particle flow code for pile tip and lateral resistance of jacked pile[J]. Journal of China University of Mining and Technology, 2010, 39(4): 622-626. [15] 周健,高冰,郭建军,等. 不同刺入深度下桩端受力模型试验及数值模拟[J]. 同济大学学报(自然科学版),2012,40(3): 379-384.ZHOU Jian, GAO Bing, GUO Jianjun, et al. Model test and numerical simulation of pile tip resistance under different penetration depths[J]. Journal of Tongji University (Natural Science), 2012, 40(3): 379-384. [16] 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,2009,31(4): 501-507. doi: 10.3321/j.issn:1000-4548.2009.04.002ZHOU Jian, DENG Yibing, YE Jianzhong, et al. Experimental and numerical analysis of jacked piles during installation in sand[J]. Chinese Journal of Geotechnical Engineering, 2009, 31(4): 501-507. doi: 10.3321/j.issn:1000-4548.2009.04.002 [17] 周健,陈小亮,王冠英,等. 开口管桩沉桩过程试验研究与颗粒流模拟[J]. 同济大学学报(自然科学版),2012,40(2): 173-178.ZHOU Jian, CHEN Xiaoliang, WANG Guanying, et al. Experimental and numerical analysis of open-ended pipe piles during jacking into sand[J]. Journal of Tongji University (Natural Science), 2012, 40(2): 173-178. [18] 周健, 陈小亮, 周凯敏, 等. 静压开口管桩沉桩过程模型试验及数值模拟[J]. 岩石力学与工程学报, 2010, 29(增刊2): 3839-3846.ZHOU Jian, CHEN Xiaoliang, ZHOU Kaimin, et al. Model test and numerical simulation of driving process of open-ended jacked pipe piles[J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(S2): 3839-3846. [19] 詹永祥,姚海林,董启朋,等. 砂土中开口管桩沉桩过程的颗粒流模拟研究[J]. 岩土力学,2013,34(1): 283-289.ZHAN Yongxiang, YAO Hailin, DONG Qipeng, et al. Study of process of open-ended pipe pile driven into sand soil by particle flow simulation[J]. Rock and Soil Mechanics, 2013, 34(1): 283-289. [20] LIU J W, DUAN N, CUI L, et al. DEM investigation of installation responses of jacked open-ended piles[J]. Acta Geotechnica, 2019, 14(6): 1805-1819. doi: 10.1007/s11440-019-00817-7 [21] 周健,李魁星,郭建军,等. 分层介质中桩端刺入的室内模型试验及颗粒流数值模拟[J]. 岩石力学与工程学报,2012,31(2): 375-381. doi: 10.3969/j.issn.1000-6915.2012.02.017ZHOU Jian, LI Kuixing, GUO Jianjun, et al. Laboratory model tests and particle flow code numerical simulation of pile tip penetration in layered medium[J]. Chinese Journal of Rock Mechanics and Engineering, 2012, 31(2): 375-381. doi: 10.3969/j.issn.1000-6915.2012.02.017 [22] 李阳, 朱洪昌, 徐金明. 成层土中桩土相互作用的颗粒流模拟[J]. 工程地质学报, 2015, 23(增刊1): 115-120.LI Yang, ZHU Hongchang, XU Jinming, et al. Numerical simulation of pile-soil interaction processes in layered soil using particle flow simulation[J]. Journal of Engineering Geology, 2015, 23(S1): 115-120. [23] DUAN N, CHENG Y P. A modified method of generating specimens for a 2D DEM centrifuge model[C]//Geo-Chicago 2016. Chicago: American Society of Civil Engineers, 2016: 610-620. [24] 周健,王家全,曾远,等. 土坡稳定分析的颗粒流模拟[J]. 岩土力学,2009,30(1): 86-90. doi: 10.3969/j.issn.1000-7598.2009.01.013ZHOU Jian, WANG Jiaquan, ZENG Yuan, et al. Simulation of slope stability analysis by particle flow code[J]. Rock and Soil Mechanics, 2009, 30(1): 86-90. doi: 10.3969/j.issn.1000-7598.2009.01.013 [25] 周博,汪华斌,赵文锋,等. 黏性材料细观与宏观力学参数相关性研究[J]. 岩土力学,2012,33(10): 3171-3175,3177.ZHOU Bo, WANG Huabin, ZHAO Wenfeng, et al. Analysis of relationship between particle mesoscopic and macroscopic mechanical parameters of cohesive materials[J]. Rock and Soil Mechanics, 2012, 33(10): 3171-3175,3177. [26] 陈建峰,李辉利,周健. 黏性土宏细观参数相关性研究[J]. 力学季刊,2010,31(2): 304-309.CHEN Jianfeng, LI Huili, ZHOU Jian. Study on the relevance of macro-micro parameters for clays[J]. Chinese Quarterly of Mechanics, 2010, 31(2): 304-309. [27] 罗勇. 土工问题的颗粒流数值模拟及应用研究[D]. 杭州: 浙江大学, 2007. [28] 宁孝梁. 黏性土的细观三轴模拟与微观结构研究[D]. 杭州: 浙江大学, 2017. [29] 雷华阳,王铁英,张志鹏,等. 高黏性新近吹填淤泥真空预压试验颗粒流宏微观分析[J]. 吉林大学学报(地球科学版),2017,47(6): 1784-1794.LEI Huayang, WANG Tieying, ZHANG Zhipeng, et al. Macro-and meso-analysis of newly formed highly viscous dredger fill under vacuum preloading using particle flow theory[J]. Journal of Jilin University (Earth Science Edition), 2017, 47(6): 1784-1794. [30] 张明义,邓安福. 预制桩静力贯入层状地基的试验研究[J]. 岩土工程学报,2000,22(4): 490-492. doi: 10.3321/j.issn:1000-4548.2000.04.021ZHANG Mingyi, DENG Anfu. Experimental study on jacked precast piles in layered soil[J]. Chinese Journal of Geotechnical Engineering, 2000, 22(4): 490-492. doi: 10.3321/j.issn:1000-4548.2000.04.021 [31] 李广信, 张丙印, 于玉贞. 土力学[M]. 北京: 清华大学出版社, 2014. [32] 李雨浓,李镜培,赵仲芳,等. 层状地基静压桩贯入过程机理试验[J]. 吉林大学学报(地球科学版),2010,40(6): 1409-1414.LI Yunong, LI Jingpei, ZHAO Zhongfang, et al. Model test research on penetration process of jacked pile in layered soil[J]. Journal of Jilin University (Earth Science Edition), 2010, 40(6): 1409-1414. [33] 叶建忠,周健. 关于桩端阻力问题的分析与研究现状[J]. 建筑科学,2006,22(2): 64-68. doi: 10.3969/j.issn.1002-8528.2006.02.015YE Jianzhong, ZHOU Jian. Analysis and review of research on the issue of pile end bearing capacity[J]. Building Science, 2006, 22(2): 64-68. doi: 10.3969/j.issn.1002-8528.2006.02.015 [34] 王永洪,张明义,白晓宇,等. 基于光纤光栅传感技术的静压沉桩贯入特性及影响因素研究[J]. 岩土力学,2019,40(12): 4801-4812.WANG Yonghong, ZHANG Mingyi, BAI Xiaoyu, et al. Study of penetration characteristics and influence factor of jacked pile based on fiber Bragg grating sensing technology[J]. Rock and Soil Mechanics, 2019, 40(12): 4801-4812. [35] HEEREMA E P, DE JONG A. An advanced wave equation computer program which simulates dynamic pile plugging through a coupled mass-spring system[M]//Numerical Methods in Offshore Piling. [S.l.]: Thomas Telford Publishing, 1980: 37-42. [36] BOND A J, JARDINE R J. Effects of installing displacement piles in a high OCR clay[J]. Géotechnique, 1991, 41(3): 341-363. [37] 王腾,张哲. 粉土界面恒刚度循环剪切试验研究[J]. 岩土工程学报,2019,41(10): 1921-1927.WANG Teng, ZHANG Zhe. Experimental studies on cyclic shear behavior of steel-silt interface under constant normal stiffness[J]. Chinese Journal of Geotechnical Engineering, 2019, 41(10): 1921-1927.