Advertisement

Journal of Central South University

, Volume 20, Issue 4, pp 1094–1102 | Cite as

Mesomechanical simulation of direct shear test on outwash deposits with granular discrete element method

  • Chong Shi (石崇)
  • Sheng-nian Wang (王盛年)Email author
  • Lin Liu (刘琳)
  • Qing-xiang Meng (孟庆祥)
  • Qiang Zhang (张强)
Article

Abstract

The mechanical properties of outwash deposits which are taken as unconsolidated geo-materials with the characteristics of non-uniformity, heterogeneity and multiphase have attracted much attention in engineering. According to the results of laboratory direct shear test on the remolded samples, the soil particle parameters of numerical model based on in-situ particle size cumulative curves and 3D granular discrete element method were determined. Then, numerical experiments on different lithology, stone content and gradation composition were conducted. The results show that it is not a flat surface but a shear band that yields in the sample. The curve of particle velocity vs distance from the designed shear surface of test model that is taken as a datum plane in the vertical section of sample shows in “S” shape. The shear disturbance area is about twice the maximum diameter of stone blocks. The greater the stiffness of stone is, the rougher the shear surface is. The shear strength of outwash deposits is largely controlled by lithology and stone content, and the bite force between stone blocks is the root reason of larger friction angle. It is also shown that strain hardening and low shear dilatancy occur under high confining pressure as well as possibility of shear shrinkage. But it is easy to behave shear dilatation and strain softening under low confining pressure. The relationship between particle frictional coefficient and stone content presents an approximately quadratic parabola increase. The strain energy first increases and then drops with the increase of frictional energy. The cohesion increases with soil stiffness increasing but decreases with stone stiffness increasing. Numerical results are consistent with the laboratory test results of remolded samples, which indicate that this method can be a beneficial supplement to determine the parameters of engineering deposit bodies.

Key words

outwash deposit direct shear test granular discrete element mesomechanics 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. [1]
    TU Guo-xiang. Study on the engineering properties and stability of typical ancient outwash congeries in southwestern valley [D]. Chengdu: Chengdu University of Technology, 2010. (in Chinese)Google Scholar
  2. [2]
    XU Wen-jie, HU Rui-lin. Conception, classification and significations of soil-rock mixture [J]. Hydrogeology & Engineering Geology, 2009, 4: 50–56. (in Chinese).Google Scholar
  3. [3]
    HOLTZ W G, GIBBS H J. Triaxial shear tests on pervious gravelly soils [J]. Journal of the Soil Mechanics and Foundations division, ASCE, 1956, 82: 1–19.Google Scholar
  4. [4]
    CHANDLER R J. The inclination of talus, arctic talus terraces, and other slopes composed of granular materials [J]. Journal of Geology, 1973, 81: 1–14.CrossRefGoogle Scholar
  5. [5]
    LINDQUIST E S, GOODMAN R E. Strength and deformation properties of a physical model [C]// Proceedings of the 1st North American Rock Mechanics Conference (NARMS). Rotterdam: A. A. Balkema, 1994: 843–850.Google Scholar
  6. [6]
    LINDQUIST E S. The strength and deformation properties of mé lange [D]. Berkeley, CA: University of California at Berkeley, 1994.Google Scholar
  7. [7]
    YOU Xin-hua, TANG Jin-song. Research on horizontal push-shear in-situ test of soil and rock-mixture [J]. Chinese Journal of Stone Mechanics and Engineering, 2002, 21(10): 1537–1540. (in Chinese).Google Scholar
  8. [8]
    WU Min-shuo, LI Xiao, HE Jian-ming. In-situ direct-shear test on rock-soil aggregate [J]. Geotechnical Engineering Technique, 2007, 21(4): 184–189. (in Chinese).Google Scholar
  9. [9]
    LI Xiao, LIAO Qiu-lin, HE Jian-ming, CHEN Jian. Study on in situ tests of mechanical characteristics on soil-rock aggregate [J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 26(12): 2377–2384. (in Chinese).Google Scholar
  10. [10]
    DONG Yun. Experimental study on intensity character of rock-soil aggregate mixture [J]. Rock and Soil Mechanics, 2007, 28(6): 1269–1274. (in Chinese).Google Scholar
  11. [11]
    ZHAO Chuan, SHI Jin-xu, TANG Hong-mei. Test and research on influence law of soil-rock ratio in Three Gorges Reservoir Region on soil strength parameters [J]. Highway, 2006, 11: 32–35. (in Chinese).Google Scholar
  12. [12]
    XU Wen-jie, HU Rui-lin, YUE Z Q, ZHANG Rui, WANG Guo-liang. Research on relationship between rock block proportion and shear strength of soil-rock mixtures based on digital image analysis and large direct shear [J]. Chinese Journal of Rock Mechanics and Engineering, 2008, 27(5): 996–1007. (in Chinese).Google Scholar
  13. [13]
    XU Wen-jie, HU Rui-lin, YUE Zhong-qi, TAN Ru-jiao. Mesostructural character and numerical simulation of mechanical properties of soil-rock mixtures [J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 26(2): 300–311. (in Chinese)).Google Scholar
  14. [14]
    HE Jian-ming, LI Xiao, WU Jian-bo, et al. Modeling method of the rock-soil aggregate and its numerical test [J]. Mining and Metallurgical Engineering, 2009, 29(3): 1–4. (in Chinese).Google Scholar
  15. [15]
    YOU Xin-hua. Stochastic structural model of the earth-rock aggregate and its application [D]. Beijing: Beijing Jiaotong University, 2001. (in Chinese)Google Scholar
  16. [16]
    JIA Xue-ming, CHAI He-jun, ZHENG Ying-ren. Mesomechanics research of large direct shear test on soil and rock aggregate mixture with particle flow code simulation [J]. Rock and Soil Mechanics, 2010, 31(9): 2695–2703. (in Chinese)Google Scholar
  17. [17]
    HE Jian-ming, LI Xiao, LI Shou-ding, GU Jin-lue. Numerical study of rock-soil aggregate by discrete element modeling [C]// FSKD 2009. Sixth International Conference on Fuzzy Systems and Knowledge Discovery. Tianjin, China: IEEE Computer Society, 2009: 565–569.CrossRefGoogle Scholar
  18. [18]
    MAIR K, HAZZARD J F. Nature of stress accommodation in sheared granular material: Insights from 3D numerical modeling [J]. Earth and Planetary Science Letters, 2007: 259, 469–485.CrossRefGoogle Scholar
  19. [19]
    MEDLEY E, LINDQUIST E S. The engineering significance of the scale-independence of some Franciscan melanges in California, USA [C]// DAEMEN J K, SCHILTZ R A ed. Proceeding of the 35th US Rock Mechanics Symposium. Rotterdam: A. A. Balkema, 1995: 907–914.Google Scholar

Copyright information

© Central South University Press and Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Chong Shi (石崇)
    • 1
    • 2
  • Sheng-nian Wang (王盛年)
    • 1
    • 2
    Email author
  • Lin Liu (刘琳)
    • 1
    • 2
  • Qing-xiang Meng (孟庆祥)
    • 1
    • 2
  • Qiang Zhang (张强)
    • 1
    • 2
  1. 1.Key Laboratory of Ministry of Education for Geomechanics and Embankment EngineeringHohai UniversityNanjingChina
  2. 2.Institute of Geotechnical EngineeringHohai UniversityNanjingChina

Personalised recommendations