动态空心圆柱扭剪试验的离散元模拟研究  

Research on discrete element simulation technology for dynamic hollow cylinder torsional shear test

作　　者：崔新壮[1] 包振昊 郝建文 杜业峰 李向阳 CUI Xinzhuang;BAO Zhenhao;HAO Jianwen;DU Yefeng;LI Xiangyang(School of Civil Engineering,Shandong University,Jinan 250061,China)

机构地区：[1]山东大学土建与水利学院,山东济南250012

出　　处：《中南大学学报（自然科学版）》2024年第10期3921-3932,共12页Journal of Central South University:Science and Technology

基　　金：国家重点研发计划项目(2022YFB2601900);国家自然科学基金资助项目(52027813,52178429,51778346);山东省自然科学基金资助项目(ZR2020ME242)。

摘　　要：为了揭示应力主轴旋转效应对土体宏细观动力特性的影响,提出土体动态空心圆柱扭剪试验的数值模拟方法,该方法采用FDM-DEM耦合技术模拟物理试验中的完全柔性边界条件,并基于动态伺服原理实现柔性约束下循环动剪应力的精确加载。以重载列车荷载为例,建立“心形”复杂应力路径下重载铁路路基土体动态空心圆柱扭剪的数值试验模型,并通过物理试验验证数值模拟方法的正确性,分析应力主轴旋转效应对土体颗粒的运动状态、局部孔隙率、平均配位数、组构等细观特性的影响。研究结果表明,重载列车荷载引起的应力主轴旋转效应加剧了表征土体细观结构各项参数的变化程度,并加快了重载铁路路基土体竖向塑性累积变形的发展。此研究实现了复杂应力路径下空心圆柱试样的动态加载数值模拟,可为阐明土体在复杂应力路径下的宏细观动力特性演化规律提供参考。In order to reveal the influence of the effect of the principal stress rotation on the macroscopic and microscopic of dynamic soil characteristics,a numerical simulation method for the dynamic hollow cylinder torsional shear test of soil was proposed.The fully flexible boundary conditions in physical experiments were simulated using FDM-DEM and the precise loading of cyclic dynamic shear stress under flexible constraints was realized based on dynamic servo principle.Taking heavy-haul train load as an example,a numerical model of dynamic hollow cylinder torsional shear test of heavy-haul railway subgrade soil under complex stress path of"heart shape"was established.The correction of this numerical simulation method was verified through physical tests,and the effect of the principal stress rotation on the mesoscopic characteristics of soil particles,such as the particle movement,local porosity,average coordination number,and fabric,was analyzed.The results indicate that the effect of the principal stress rotation caused by heavy-haul train load enlarges the changes in various parameters characterizing the microstructure of soil and accelerates the development of vertical plastic cumulative deformation of the heavy-haul railway subgrade soil.The numerical simulation of dynamic loading of hollow cylindrical test with complex stress paths is achieved which provides reference for the evolution laws of macroscopic and microscopic dynamic characteristics of soil with complex stress paths.

关 键 词：离散元 动态空心圆柱扭剪试验 重载列车荷载 应力主轴旋转 重载铁路路基 

分 类 号：TU411[建筑科学—岩土工程]