三维离散元大尺度模拟中变粒径方法的优化及其应用  

Refinement and application of variable particle-size methods in 3D discrete element modelling for large-scale problems

作　　者：邓益兵[1] 杨彦骋 史旦达[1] 刘文白[1] 

机构地区：[1]上海海事大学海洋科学与工程学院,上海201306 [2]中交上海航道勘察设计研究院有限公司,上海200120

出　　处：《岩土工程学报》2017年第1期62-70,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金青年基金项目(51208294);上海市教委一流学科建设项目;上海市教委科研创新项目(15ZZ081);2013年上海市研究生教育创新计划实施项目(20131129);上海海事大学学术创新团队(A2-0201150404)

摘　　要：在已有的变粒径建模方法基础上,针对不同粒径区宏观弹性不一致和界面区大小颗粒互相渗入两个问题进行优化。通过在近场核心区域采用小粒径颗粒模拟真实土颗粒,远场边界区域逐级放大颗粒粒径,不同粒径之间采用相同密实度的混合粒径模拟,实现三维大尺度离散元模拟,以减少模拟颗粒数量提升运算速度。基于宏观弹性一致条件,建立静力条件下几何上等比例放大颗粒体系的颗粒材料参数尺度关系,并满足应力、应变和应变能一致性,通过三轴模拟验证了宏观弹性一致性。在变粒径交界处设置密实度与均一颗粒区一致的混合层有效防止大小颗粒互相渗入,变形特性与均一颗粒区趋于一致,并提出了两种粒径颗粒混合生成特定密实度的方法。最后,通过模拟静力触探试验(CPT),表明该方法的有效性。该方法可为三维离散元模拟工程大尺度问题提供新途径。A refinement method is proposed to solve the difference in the macroscopic elasticity and the interpenetration in interface area between different particle-size areas in the DEM. In simulations of 3D DEM large-scale problems, small balls are used in the near field core area to simulate the real soil, while the far field boundary regions are filled with larger balls. In addition, a mixed area is set between different particle-size areas with the same relative density. The number of particles in the model can be reduced enormously, which improves largely the calculation efficiency. For scaling particle systems, the scale relationship is established on the static condition by the identical macro elasticity of uniform granules. The relationship satisfies the consistency of stress, strain and strain energy. The results of a series of triaxial test simulations verify the uniformity of macro elasticity. A method to generate a certain density mixture with two different particle sizes is proposed. The results of DEM simulations illustrate that the deformation property of mixed area is consistent with that of the uniform particles. Finally, the results of cone penetration test simulations show that the proposed method is effective. This study may provide a new approach to the application of 3D discrete element modelling in the large-scale geoteehnical engineering.

关 键 词：离散元模拟 变粒径 弹性常数 尺度关系 相对密实度 静力触探 

分 类 号：TU43[建筑科学—岩土工程]