A meso-scale study of the influence of particle shape on shear deformation of coarse-grained soil
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摘要:
颗粒形状是影响粗粒土密实度、力学与渗流等特性的主要因素之一。为了分析颗粒形状对粗粒土剪切特性的影响，采用离散元法生成4种不同形状的颗粒组，进行粗粒土直剪试验模拟与剪切宏细观响应研究，得出了颗粒形状对剪应力-剪位移、体应变-剪位移的影响，分析了粗粒土剪切应力、应变特性与剪胀特性。通过分析剪切带厚度、颗粒旋转量值、平均接触数、孔隙率及接触力系等宏细观参量的演化规律，研究颗粒形状在宏细观尺度上对粗粒土的影响。研究表明：异形颗粒间的咬合自锁作用大于纯圆颗粒，试样的抗剪强度有随形状系数的减小而增大的趋势。试样颗粒在外荷载作用下发生运动，应变主要表现在颗粒运动剧烈、剪胀幅度较大的剪切带内。颗粒形状系数F减小，试样的初始平均接触数增加，内摩擦角φ增大，剪切带内孔隙率增量越大，剪胀幅度越大。剪切过程中强力链聚集于剪切带内并起骨架作用，随着形状系数的减小，力链长度在0～5所占百分比呈增大趋势；剪切带内强力链的数目随着形状系数的减小而增加，峰值含量在30%～35%之间。
Abstract:Particle shape is one of the main factors that affect the compactness, mechanics and seepage of coarse-grained soil. In order to analyze the influence of particle shape on the shear characteristics of coarse-grained soil, the discrete element method is used to generate four different particle groups. The direct shear test simulation and macro-micro shear response research of coarse-grained soil are carried out. The influence of particle shape on shear stress-shear displacement and volume strain-shear displacement is obtained. The shear stress, strain characteristics and dilatancy characteristics of coarse-grained soil are analyzed. The influence of particle shape on coarse-grained soil on macro-micro scale is studied by analyzing the evolution law of macro-micro parameters such as shear zone thickness, particle rotation value, average contact number, porosity and contact force system. The results show that the self-locking effect of the special-shaped particles is greater than that of the pure round particles, and the shear strength of the sample tends to increase with the decreasing shape coefficient. The sample particles move under the action of external load, and the strain is mainly shown in the shear zone where the particles move violently and dilate greatly. The particle shape coefficient decreases, the initial average contact number of the sample increases, the internal friction angle "φ" increases, and the larger the increment of porosity in the shear band, the larger the dilatancy amplitude. During the shearing process, the strong chain gathers in the shearing zone and acts as a skeleton. With the decrease in the shape coefficient, the percentage of the force chain length in the range of 0 - 5 increases. The number of strong chains in the shear band increases with the decrease in the shape coefficient, and the peak value content ranges between 30% and 35%.
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Key words:
- coarse-grained soil /
- particle shape /
- shear deformation /
- discrete element /
- mechanics mechanism
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表 1 形状参数统计表
Table 1. Statistics of the shape coefficients
试样颗粒 F1 F2 F a 1.000 1.000 1.000 b 0.912 0.728 0.820 c 0.910 0.650 0.780 d 0.799 0.644 0.722 
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表 2 模型细观参数
Table 2. Mesoscopic parameters of the model
颗粒密度
ρs/（kg·m−3）初始孔隙率ns 颗粒法向
接触刚度
kn/（N·m−1）颗粒切向
接触刚度
kn/（N·m−1）粒间摩擦
系数fc墙体法向
接触刚度/
（N·m−1）2643 0.13 4.0×107 3.0×107 0.6 2×108
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[1] 丁瑜, 饶云康, 倪强, 等. 颗粒级配与孔隙比对粗粒土渗透系数的影响[J]. 水文地质工程地质,2019,46(3):108 − 116. [DING Yu, RAO Yunkang, NI Qiang, et al. Effects of gradation and void ratio on the coefficient of permeability of coarse-grained soil[J]. Hydrogeology & Engineering Geology,2019,46(3):108 − 116. (in Chinese with English abstract)
[2] 罗伟锦, 杨兰强, 熊署丹. 考虑颗粒破碎的无黏性粗粒料的剪胀模型研究[J]. 水文地质工程地质,2015,42(6):71 − 79. [LUO Weijin, YANG Lanqiang, XIONG Shudan. Dilatancy model including particle breakage for cohesion less coarse aggregates[J]. Hydrogeology & Engineering Geology,2015,42(6):71 − 79. (in Chinese with English abstract)
[3] 李涛, 付宏渊, 周功科, 等. 降雨入渗条件下粗粒土路堤暂态饱和区发展规律及稳定性研究[J]. 水文地质工程地质,2013,40(5):74 − 80. [LI Tao, FU Hongyuan, ZHOU Gongke, et al. A study of development law and stability of transient saturated areas of coarse-grained soil embankment under rainfall infiltration[J]. Hydrogeology & Engineering Geology,2013,40(5):74 − 80. (in Chinese with English abstract)
[4] 史乃伟, 李飒, 刘小龙, 等. 粗砂直剪试验与离散元细观机理分析[J]. 科学技术与工程,2019,19(5):261 − 266. [SHI Naiwei, LI Sa, LIU Xiaolong, et al. Critical state test and meso mechanism of sand[J]. Science Technology and Engineering,2019,19(5):261 − 266. (in Chinese with English abstract) doi: 10.3969/j.issn.1671-1815.2019.05.040
[5] 刘洋, 吴顺川, 周健. 单调荷载下砂土变形过程数值模拟及细观机制研究[J]. 岩土力学,2008,29(12):3199 − 3204. [LIU Yang, WU Shunchuan, ZHOU Jian. Numerical simulation of sand deformation under monotonic loading and mesomechanical analysis[J]. Rock and Soil Mechanics,2008,29(12):3199 − 3204. (in Chinese with English abstract) doi: 10.3969/j.issn.1000-7598.2008.12.004
[6] GUO Y G. Influence of normal stress and grain shape on granular friction: Results of discrete element simulations[J]. Journal of Geophysical Research Atmospheres,2004,109(B12):B12305. doi: 10.1029/2004JB003044
[7] MORGAN J K, BOETTCHER M S. Numerical simulations of granular shear zones using the distinct element method: 1. Shear zone kinematics and the micromechanics of localization[J]. Journal of Geophysical Research: Solid Earth,1999,104(B2):2703 − 2719. doi: 10.1029/1998JB900056
[8] ROTHENBURG L, BATHURST R J. Analytical study of induced anisotropy in idealized granular materials[J]. Géotechnique,1989,39(4):601 − 614. doi: 10.1680/geot.1989.39.4.601
[9] 朱泽奇, 盛谦, 程红战, 等. 基于直接生成法的土石混合体三维随机模型构建与数值仿真研究[J]. 岩土力学,2017,38(4):1188 − 1194. [ZHU Zeqi, SHENG Qian, CHENG Hongzhan, et al. 3D stochastic model and numerical simulation of soil-rock mixture based on direct method[J]. Rock and Soil Mechanics,2017,38(4):1188 − 1194. (in Chinese with English abstract)
[10] 杨贵, 许建宝, 孙欣, 等. 颗粒形状对人工模拟堆石料强度和变形特性影响的试验研究[J]. 岩土力学,2017,38(11):3113 − 3118. [YANG Gui, XU Jianbao, SUN Xin, et al. Experimental study of influence of particle shape on strength and deformation for artificial rockfill materials[J]. Rock and Soil Mechanics,2017,38(11):3113 − 3118. (in Chinese with English abstract)
[11] 王鹏程, 刘建坤. 颗粒形状对不良级配碎石集料剪切特性的影响[J]. 岩土力学,2017,38(8):2198 − 2202. [WANG Pengcheng, LIU Jiankun. Effect of particle shape on the shear behavior of open-graded crushed aggregate[J]. Rock and Soil Mechanics,2017,38(8):2198 − 2202. (in Chinese with English abstract)
[12] 张程林, 周小文. 砂土颗粒三维形状模拟离散元算法研究[J]. 岩土工程学报,2015,37(增刊1):115 − 119. [ZHANG Chenglin, ZHOU Xiaowen. Algorithm for modelling three-dimensional shape of sand based on discrete element method[J]. Chinese Journal of Geotechnical Engineering,2015,37(Sup1):115 − 119. (in Chinese with English abstract)
[13] 刘广, 荣冠, 彭俊, 等. 矿物颗粒形状的岩石力学特性效应分析[J]. 岩土工程学报,2013,35(3):540 − 550. [LIU Guang, RONG Guan, PENG Jun, et al. Mechanical behaviors of rock affected by mineral particle shapes[J]. Chinese Journal of Geotechnical Engineering,2013,35(3):540 − 550. (in Chinese with English abstract)
[14] 何亮, 魏玉峰, 潘远阳, 等. 基于能量耗散机制的粗粒土圆度损伤特性分析[J]. 水文地质工程地质,2019,46(5):120 − 126. [HE Liang, WEI Yufeng, PAN Yuanyang Y, et al. Analyses of roundness damage characteristics of coarse-grained soil based on energy dissipation mechanism[J]. Hydrogeology & Engineering Geology,2019,46(5):120 − 126. (in Chinese with English abstract)
[15] DODDS J S. Particle shape and stiffness-effects on soil behavior[D]. Atlanta: Georgia Institute of Technology, 2003.
[16] 刘清秉,项伟, LEHANE B M, 等. 颗粒形状对砂土抗剪强度及桩端阻力影响机制试验研究[J]. 岩石力学与工程学报, 2011, 30(2): 400−409.
LIU Qingbing, XIANG Wei, LEHANE B M, et al. Experimental study of effect of particle shapes on shear strength of sand and tip resistance of driven piles[J]. Chinese Journal of Rock Mechanics and Engineering, 2011, 30(2): 400−409. (in Chinese with English abstract)
[17] 史旦达, 周健, 刘文白, 等. 砂土单调剪切特性的非圆颗粒模拟[J]. 岩土工程学报,2008,30(9):1361 − 1366. [SHI Danda, ZHOU Jian, LIU Wenbai, et al. Numerical simulation for behaviors of sand with non-circular particles under monotonic shear loading[J]. Chinese Journal of Geotechnical Engineering,2008,30(9):1361 − 1366. (in Chinese with English abstract) doi: 10.3321/j.issn:1000-4548.2008.09.017
[18] 孔亮, 彭仁. 颗粒形状对类砂土力学性质影响的颗粒流模拟[J]. 岩石力学与工程学报,2011,30(10):2113 − 2119. [KONG Liang, PENG Ren. Particle flow simulation of influence of particle shape on mechanical properties of quasi-sands[J]. Chinese Journal of Rock Mechanics and Engineering,2011,30(10):2113 − 2119. (in Chinese with English abstract)
[19] 张翀, 舒赣平. 颗粒形状对颗粒流模拟双轴压缩试验的影响研究[J]. 岩土工程学报,2009,31(8):1281 − 1286. [ZHANG Chong, SHU Ganping. Effect of particle shape on biaxial tests simulated by particle flow code[J]. Chinese Journal of Geotechnical Engineering,2009,31(8):1281 − 1286. (in Chinese with English abstract) doi: 10.3321/j.issn:1000-4548.2009.08.020
[20] 任树林, 曾亚武, 赵凯. 颗粒形状对断层摩擦强度影响的数值试验研究[J]. 水利与建筑工程学报,2019,17(3):42 − 47. [REN Shulin, ZENG Yawu, ZHAO Kai. Numerical experiments on the effects of particle shape on frictional strength of faults[J]. Journal of Water Resources and Architectural Engineering,2019,17(3):42 − 47. (in Chinese with English abstract) doi: 10.3969/j.issn.1672-1144.2019.03.007
[21] 郑俊杰, 赖汉江, 董友扣, 等. 桩承式路堤承载特性颗粒流细观模拟[J]. 华中科技大学学报(自然科学版),2012,40(11):43 − 47. [ZHENG Junjie, LAI Hanjiang, DONG Youkou, et al. Mesomechanical analysis of bearing characteristics of pile-supported embankment with particle flow code[J]. Journal of Huazhong University of Science and Technology(Natural Science Edition),2012,40(11):43 − 47. (in Chinese with English abstract)
[22] WANG J, DOVE J E, GUTIERREZ M S. Discrete-continuum analysis of shear banding in the direct shear test[J]. Géotechnique,2007,57(6):513 − 526. doi: 10.1680/geot.2007.57.6.513
[23] 蒋明镜, 王富周, 朱合华. 单粒组密砂剪切带的直剪试验离散元数值分析[J]. 岩土力学,2010,31(1):253 − 257. [JIANG Mingjing, WANG Fuzhou, ZHU Hehua. Shear band formation in ideal dense sand in direct shear test by discrete element analysis[J]. Rock and Soil Mechanics,2010,31(1):253 − 257. (in Chinese with English abstract) doi: 10.3969/j.issn.1000-7598.2010.01.043
[24] ODA M, KAZAMA H, KONISHI J. Effects of induced anisotropy on the development of shear bands in granular materials[J]. Mechanics of Materials,1998,28(1/2/3/4):103 − 111.
[25] 周伦伦. 颗粒破碎与形状对颗粒材料力学性质影响的离散元研究[D]. 武汉: 武汉大学, 2017.
ZHOU Lunlun. Dem investigation of influence of particle breakage and shape on the mechanical behaviors of granular materials[D]. Wuhan: Wuhan University, 2017.(in Chinese with English abstract)
[26] IWASHITA K, ODA M. Rolling resistance at contacts in simulation of shear band development by DEM[J]. Journal of Engineering Mechanics,1998,124(3):285 − 292. doi: 10.1061/(ASCE)0733-9399(1998)124:3(285)
[27] ESTRADA N, AZÉMA E, RADJAI F, et al. Identification of rolling resistance as a shape parameter in sheared granular media[J]. Physical Review E,2011,84:011306. doi: 10.1103/PhysRevE.84.011306
[28] ODA M. Co-ordination number and its relation to shear strength of granular material[J]. Soils and Foundations,1977,17(2):29 − 42. doi: 10.3208/sandf1972.17.2_29
[29] 孙其诚, 金峰, 王光谦, 等. 二维颗粒体系单轴压缩形成的力链结构[J]. 物理学报, 2010, 59(1): 30−37.
SUN Qicheng, JIN Feng, WANG Guangqian, et al. Force chains in a uniaxially compressed static granular matter in 2D[J]. Acta Physica Sinica, 2010, 59(1): 30−37. (in Chinese with English abstract)
[30] 孙其诚, 辛海丽, 刘建国, 等. 颗粒体系中的骨架及力链网络[J]. 岩土力学,2009,30(增刊1):83 − 87. [SUN Qicheng, XIN Haili, LIU Jianguo, et al. Skeleton and force chain network in static granular material[J]. Rock and Soil Mechanics,2009,30(Sup1):83 − 87. (in Chinese with English abstract)
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