多围压下三轴压缩试验与不可破裂颗粒离散元法分析

采用大型三轴试验仪器对道砟散体材料进行试验,重点研究不同围压条件下三轴试验力学特性与影响规律。同时基于离散单元法(DEM),采用非破裂不规则颗粒簇,在伺服条件下建立道砟三轴试验散粒体模型,对道砟颗粒在不同围压下进行相关数值三轴模拟,探讨偏应力、体应变、围压、体积应变与轴应变之间的关系,反映道砟基本力学特性。研究结果表明：采用离散单元方法进行数值模拟与室内三轴试验得到的一系列应力-应变规律基本一致,验证了离散单元法在道砟研究中的可行性与可靠性。同时,围压对道砟散体变形、最大偏应力、偏应力比值具有影响,其中随着围压提高道砟变形降低,因此在有砟道床设计和养护维修中,增大道床围压可降低道床沉降与变形。

BALLAST TRIAXIAL TESTS AND NON-BREAKABLE PARTICLE DISCRETE ELEMENT METHOD ANALYSIS UNDER DIFFERENT CONFINING PRESSURES

Large-scale triaxial tests were employed to investigate mechanical properties of railway ballast under different confining pressures. Meanwhile, the discrete element method (DEM) was applied to investigate the micro-characteristics of the ballast triaxial tests, in which the ballast particles were considered irregular non-breakable particles. The servo system was incorporated in the triaxial tests DEM simulation, and the relationships between the deviator stress, volume strain, confining pressure and the axial strain were analyzed. The DEM simulation results agreed well with the triaxial tests which validated the feasibility and reliability of DEM. Meanwhile, both the test and simulation results showed a strong influence of the confining pressure on the deformation and the maximum value and ratio of deviator stressby. The increase in the confining pressure leads to a decrease in ballast deformation. This information can be used in ballasted track design and maintenance.