平均粒径对砂土剪切特性的影响及细观机理

doi:10.13278/j.cnki.jjuese.20190081

摘要/Abstract

摘要： 针对平均粒径对砂土剪切特性的影响作用，结合室内试验和离散元模拟方法对不同平均粒径砂土进行了细观研究。基于3种不同平均粒径砂土的直剪试验结果，通过建立反映砂土剪切试验特征的PFC（particle flow code）颗粒流模型，详细研究了不同粒径砂土在剪切过程中土样体积变化、力链网络、孔隙率和配位数等细观结构参数的变化特征和规律，并从细观角度分析了颗粒粒径对土样宏观剪切特性的影响机制。结果表明：具有不同平均粒径砂土的细观结构参数在剪切过程中存在显著差异，并且其细观参数差异主要集中体现在剪切带处；剪切力学特性的影响主要体现在抗剪强度和剪胀效应方面，砂土平均粒径越大，抗剪强度越高，剪胀效应越明显；具有不同平均粒径的砂土在剪切过程中土颗粒运动规律及剪切带形态变化特征存在一定的差异，平均粒径越大，剪切带内上跨式颗粒占比越大，剪切带厚度越大。

关键词: 砂土, 平均粒径, 直剪试验, 离散元, 剪切带

Abstract: In the view of the effect of average particle size on the shear behavior of sand, a meso-level research was carried out by indoor tests and discrete element simulation methods. Based on the results of three direct shear tests with different average particle size, the PFC (particle flow code) particle flow model reflecting the characteristics of sand shear test was established to study in detail the variation characteristics and laws of soil sample changes, force chain network, porosity, coordination number,and other microscopic structural parameters of sandy soil with different particle sizes during the shear process;And the effect of particle size on the macroscopic shear behavior was analyzed from the microscopic perspective. The research results demonstrate that there are significant differences in the sand shear meso-parameters with different average particle sizes, and the differences are mainly reflected in the shear zone. The effect of average particle size of sand on its shear mechanical properties is mainly reflected in its shear strength and dilatancy deformation. The larger the average particle size is, the higher the shear strength is,and the more obvious the dilatancy effect is. There is a certain difference between the soil particle movement law and the morphological change characteristics of the shear zone during the shearing process:the larger the average particle size is, the larger the proportion of up span particles in the shear band is, and the larger the thickness of the shear band is.

Key words: sand, average particle size, direct shear test, discrete element method, shear band

中图分类号:

洪勇, 李子睿, 唐少帅, 王陆阳, 李亮. 平均粒径对砂土剪切特性的影响及细观机理[J]. 吉林大学学报(地球科学版), 2020, 50(6): 1814-1822.

Hong Yong, Li Zirui, Tang Shaoshuai, Wang Luyang, Li Liang. Effect of Average Particle Size on Shear Properties of Sand and Its Mesomechanical Analysis[J]. Journal of Jilin University(Earth Science Edition), 2020, 50(6): 1814-1822.

参考文献

[1] 郑颖人,孔亮. 岩土塑性力学[M]. 北京:中国建筑出版社,2010:11-14. Zheng Yingren, Kong Liang.Geotechnical Plastic Mechanics[M]. Beijing:China Construction Industry Press, 2010:11-14.
[2] 周杰,周国庆,赵光思,等. 高应力下剪切速率对砂土抗剪强度影响研究[J].岩土力学,2010,31(9):2806-2809. Zhou Jie, Zhou Guoqing, Zhao Guangsi, et al. Effect of Shear Rate on Shear Strength of Sand Under High Stress[J]. Geotechnical Mechanics, 2010, 31(9):2806-2809.
[3] 洪勇,周蓉,郑孝玉. 不同排水条件下饱和砂土快速大剪切力学特性[J].吉林大学学报(地球科学版),2018,48(5):1417-1426. Hong Yong, Zhou Rong, Zheng Xiaoyu. Fast Shear Mechanical Properties of Saturated Sand Under Different Drainage Conditions[J]. Journal of Jilin University (Earth Science Edition), 2018, 48(5):1417-1426.
[4] 孔亮,季亮亮,曹杰峰. 应力路径和颗粒级配对砂土变形影响的细观机制[J].岩石力学与工程学报,2013,32(11):2334-2341. Kong Liang, Ji Liangliang, Cao Jiefeng. Mechanical Mechanism of Stress Path and Particle Size Matching Sand Deformation[J]. Chinese Journal of Rock Mechanics and Engineering, 2013, 32(11):2334-2341.
[5] 孙其诚,王光谦. 颗粒物质力学导论[M]. 北京:科学出版社,2009:1-19. Sun Qicheng, Wang Guangqian. Introduction to Granular Matter Mechanics[M]. Beijing:Science Press, 2009:1-19.
[6] 李爽,刘洋,吴可嘉. 砂土直剪试验离散元数值模拟与细观变形机理研究[J].长江科学院院报,2017,34(4):104-110. Li Shuang, Liu Yang, Wu Kejia. Exploring Mesoscopic Deformation Mechanism of Sand in Direct Shear Test by Numverical Simulation Using Discrete Element Method[J]. Journal of Yangtze River Scientific Research Institute, 2017,34(4):104-110.
[7] Alshibli K, Stuer S. Shear Band Formation in Plane Strain Experiment of Sand[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2000, 126(6):456-503.
[8] Masson S, Martsuoka H. On the Interface Friction in Direct Shear Test[J]. Computers and Geotechnics, 2005, 32(5):317-325.
[9] Jiang M J, Yu H S, Harris D. Kinematic Variables Bridging Discrete and Continuum Granular Mechanics[J]. Mechanics Research Communications, 2006, 33:651-666.
[10] 曾远,周健. 砂土的细观参数对宏观特性的影响研究[J]. 地下空间与工程学报,2008,4(3):499-503. Zeng Yuan, Zhou Jian. Influence of Micro Parameters of Sandy Soil on Its Macro Properties[J]. Chinese Journal of Underground Space and Engineering, 2008,4(3):499-503.
[11] Sitharam T G, Nimbkar M S. Micromechanical Modeling of Granular Materials:Effect of Particle Size and Gradation[J]. Geotechnical and Geological Engineering, 2000, 18(2):91-117.
[12] 周健,池毓蔚,池永,等. 砂土双轴试验的颗粒流模拟[J]. 岩土工程学报,2000,22(6):701-704. Zhou Jian, Chi Yuwei, Chi Yong, et al. Simulation of Particle Flow in Sand-Soil Biaxial Test[J]. Journal of Geotechnical Engineering, 2000,22(6):701-704.
[13] Mishra B K, Meherotra S P. Modeling of Particle Stratification in Jigs by the Discrete Element Method[J]. Minerals Engineering, 1998, 11(6):511-522.
[14] 尹小涛,郑亚娜,马双科. 基于颗粒流数值试验的岩土材料内尺度比研究[J]. 岩土力学,2011, 32(4):1211-1215. Yin Xiaotao, Zheng Yana, Ma Shuangke. Study of Inner Scale Ratio of Rock and Soil Material Based on Numerical Tests of Particle Flow Code[J]. Rock and Soil Mechanics,2011, 32(4):1211-1215.
[15] 刘海涛,程晓辉. 粗粒土尺寸效应的离散元分析[J]. 岩土力学,2009,30(增刊1):287-292. Liu Haitao, Cheng Xiaohui. Discrete Element Analysis for Size Effects of Coarse-Grained Soils[J]. Rock and Soil Mechanics,2009, 30(Sup.1):287-292.
[16] 史旦达,周健,刘文白,等. 砂土直剪力学性状的非圆颗粒模拟与宏细观机理研究[J]. 岩土工程学报,2010,32(10):1557-1565. Shi Danda, Zhou Jian, Liu Wenbai, et al. Exploring Macro- and Micro-Scale Responses of Sand in Direct Shear Tests by Numerical Simulations Using Non-Circular Particles[J]. Chinese Journal of Geotechnical Engineering, 2010, 32(10):1557-1565.
[17] 石崇,张强,王盛年. 颗粒流(PFC5.0)数值模拟技术及应用[M]. 北京:中国建筑工业出版社,2018:246-247. Shi Chong, Zhang Qiang, Wang Shengnian. Numerical Simulation Technology and Application with Particle Flow Code(PFC5.0)[M]. Beijing:China Architecture & Building Press, 2018:246-247.
[18] Dresche A, Vardoulakis I G, Han C. A Biaxial Apparatus for Testing Soils[J]. Geotechnical Testing Journal, 1990, 13(3):226-234.
[19] Finno R J, Harris W W, Mooney M A, et al. Strain Localization and Undrained Steady State of Sand[J]. Journal of Geotechnical Engineering, 1991, 122(6):462-473.

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