MACRO-AND MESO-MECHANISM STUDY OF STRAIN LOCALIZATION IN GRANULAR MATERIAL
YANG Han1,XU Wenjie1,ZHANG Qibin2
(1. State Key Laboratory of Hydroscience and Hydraulic Engineering,Tsinghua University,Beijing 100084,China;2. Tianjin Municipal Engineering Design and Research Institute,Tianjin 300051,China)
Abstract:The strain localization in granular material due to its internal fabric under external load is a popular topic in the field of geotechnical engineering. However,current studies have focused on the analysis of statistical parameters,while the intrinsic link between the macroscopic phenomena and the mesoscopic mechanism has been ignored. The macroscopic and mesoscopic mechanical characteristics and the mechanism of deformation failure in the direct shear tests were systematically analyzed with the discrete element method(DEM). According to the development of shear stress ratio under the different normal stresses during the shearing process,anti-friction properties of granular material were discussed from the perspective of particle movement. A synchronic development between the anisotropic parameters of fabric and the macro-scale stress ratio was found. Through the statistical analysis of particle rotation,the friction between particles was revealed to be an important factor to maintain the relative stability of the mesoscopic structure. The morphological analysis of the networks of force chains revealed an agreement between the direction of principle stress and the principle direction of anisotropy. The decrease of the force chain intensity and the increase of porosity during the shearing tests were discovered. Two main mechanical models of force chain structures under different normal stresses were proposed. The fluctuation of macro-scale mechanical parameters was explained with the stability of system and the cumulative release of energy,showing the microscopic mechanism of deformation localization and dilatancy.
刘 洋. 砂土的各向异性强度准则: 应力诱发各向异性[J]. 岩土工程学报,2013,35(3):460-468.(LIU Yang. Anisotropic strength criteria of sand:Stress-induced anisotropy[J]. Chinese Journal of Geotechnical Engineering,2013,35(3):460-468.(in Chinese))
[19]
BOSKO J T,TORDESILLAS A. Evolution of Contact Forces,Fabric,and their Collective Behavior in Granular Media under Deformation:A DEM Study[C]// Earth and Space 2006@ sEngineering,Construction,and Operations in Challenging Environment. ASCE,2006:1-8.
Your browse does not support frame!