基于离散元-有限差分耦合的轨枕垫对有砟道床横向阻力的影响机制  

Mechanism of under-sleeper pads influencing lateral resistance of ballasted trackbed based on coupled discrete element-finite difference method(DEM-FDM)simulations

作　　者：谭攀 肖源杰 姜钰 王萌 王小明 张冲冲 TUTUMLUER Erol TAN Pan;XIAO Yuanjie;JIANG Yu;WANG Meng;WANG Xiaoming;ZHANG Chongchong;TUTUMLUER Erol(School of Civil Engineering,Central South University,Changsha 410075,China;MOE Key Laboratory of Engineering Structures of Heavy Haul Railway,Central South University,Changsha 410075,China;University of Illinois at Urbana−Champaign,Urbana 61801,America)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]重载铁路工程结构教育部重点实验室(中南大学),湖南长沙410075 [3]伊利诺伊大学香槟分校,香槟61801,美国

出　　处：《中南大学学报（自然科学版）》2024年第2期457-472,共16页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(U1934209,52178443,51878673);中国铁道科学研究院科技研究开发计划重大课题(2020YJ022,2019YJ026);重载铁路工程结构教育部重点实验室(中南大学)开放课题(2021JZZ01,2021JZZ02,2022JZZ03)。

摘　　要：轨枕垫(USP)因其良好的减震性能已广泛应用于铁路轨道结构,现有研究大多集中于USP对轨道结构刚度和振动响应的影响,但对有砟道床横向阻力影响的研究很少。为深入分析USP对道床横向阻力的影响并揭示其作用机理,建立轨枕-USP-有砟道床-路基三维系统的精细化离散元-有限差分(DEM-FDM)耦合数值模型,采用典型重载铁路有砟道床横向阻力现场实测结果对模型进行标定和验证,进而模拟分析不同工况组合下USP对轨枕不同位置处(枕底、枕侧和枕端)的横向阻力、道砟颗粒运动和粒间接触力等宏微观指标的影响机制。研究结果表明:在相同的轨枕横向位移下,相较于无USP的轨枕,带USP的轨枕其枕底道砟颗粒运动范围更大,横向阻力也更大,且横向阻力增加部分主要来源于枕底USP的不平整性;USP刚度越大,道床横向阻力也越大;采用USP可增加枕底的横向剪应力和最大法向接触力,且两者数值均随USP刚度的增大而增大。The under-sleeper pad(USP)is extensively used in railway track structures due to its desired damping performance.The impact of USP on the stiffness and dynamic responses of track structures is well documented in the majority of the existing studies.However,few studies focus on its influence on the lateral resistance of ballast bed.To address this deficiency and further disclose its governing mechanisms,a refined numerical model coupling discrete element-finite difference methods(DEM-FDM)was established for the three-dimensional(3D)sleeper-USP-ballast bed-subgrade system.The numerical model was subsequently calibrated and verified by using field-measured lateral resistance results of the ballast bed of a typical heavy-haul railroad.The influencing mechanisms of USP on the multiscale performance indicators including lateral resistance of different parts(i.e.,the bottom,side,and end)of the loaded rail sleeper,ballast particle motion and inter-particle contact forces were simulated and analyzed from a variety of numerical simulation scenarios.The results show that at the same level of lateral sleeper displacement,the mobilized ballast particles under the rail sleeper with USP are located in a greater depth than those under the rail sleeper without USP,thus resulting in greater lateral resistance of the rail sleeper.The unevenness of the USP surface is a major contributing factor of the increase in lateral sleeper resistance.Greater USP stiffness results in higher lateral sleeper resistance.The use of the USP can increase the lateral shear stress and the maximum normal contact forces within the ballast bed underneath the rail sleeper,both of which increase with the increase of the USP stiffness.

关 键 词：铁路轨道 有砟道床 道砟 轨枕垫 横向阻力 离散元-有限差分耦合 

分 类 号：TU45[建筑科学—岩土工程]