基于大型动三轴试验和图形分析法的有砟道床劣化特性研究  

Degradation Mechanism of Railway Ballast by Large-scale Cyclic Triaxial Test and Image Analysis Method

作　　者：常建梅[1] 李晓慧 张伏光[1] 梁世川 冯怀平[1] CHANG Jianmei;LI Xiaohui;ZHANG Fuguang;LIANG Shichuan;FENG Huaiping(State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures,Shijiazhuang Tiedao University,Shijiazhuang 050043,China;HeBei Townhoo Road&Bridge Engineering Co.,Ltd.,Xingtai 054000,China)

机构地区：[1]石家庄铁道大学省部共建交通工程结构力学行为与系统安全国家重点实验室,河北石家庄050043 [2]河北通昊路桥工程有限公司,河北邢台054000

出　　处：《铁道学报》2022年第7期107-116,共10页Journal of the China Railway Society

基　　金：国家自然科学基金(51478279);中央引导地方科技发展资金(216Z1805G);国家重点实验室自主课题(ZZ2020-11);省部共建交通工程结构力学行为与系统安全国家重点实验室科研启动费(SKLQN2022-3);省部共建交通工程结构力学行为与系统安全国家重点实验室引导性课题(SKLYD2022-3)。

摘　　要：为揭示列车长期动荷载作用下有砟道床劣化规律,开展大型动三轴试验,研究道砟试样在循环荷载作用下的累积应变、滞回圈、动弹性模量以及阻尼比等宏观力学行为演变规律。同时,采用三维激光扫描仪并结合图形分析法从细观尺度分析动荷载作用下道砟颗粒劣化规律。研究结果表明:道砟试样永久变形行为符合塑性安定和棘轮行为特征;随循环次数增加,试样应变硬化现象逐渐增强且增长趋势变缓,动弹性模量表现出先增加、后减小、再增加最终趋于稳定的变化规律,阻尼比则先缓慢上升随后急剧下降,并从细观尺度对其劣化现象进行解释。分析试验结束后发生明显劣化的道砟形态可以看出,主要劣化形式为尖角折断,发生尖角折断的道砟会导致其棱角性减弱,试验后道砟形状更接近球形;相对于立方状道砟,片状和针状道砟更易发生劣化;道砟粒径越大,越容易发生劣化。相比于洛杉矶磨耗试验,动三轴试验由于更贴近道砟实际受力条件而更能揭示道砟劣化进程。In order to investigate the degradation mechanism of railway ballast subjected to dynamic loading,a large-scale triaxial test was conducted,and the evolution law of macroscopic mechanical behavior such as cumulative strain,hysteretic loop,dynamic elastic modulus and damping ratio of ballast under cyclic load was studied.In addition,by using a three-dimensional laser scanner combined with image analysis method,the change of ballast particle geometry under cyclic load was obtained at the micro scale.The test results show that the ballast specimen exhibits deformation behavior of plastic shakedown and ratcheting.As cyclic number increases,the strain-hardening behavior is more distinguished,and the dynamic elastic modulus presents increase-decrease-increase trend and finally remains almost constant.As for the damping ratio,it firstly increases and then abruptly decreases with increase of cyclic number.The aforementioned macroscopic behavior can be related to microscopic responses.By analyzing the obviously degraded ballasts,the main form of ballast degradation is breakage of angular corners.At the end of test,for each ballast particle undergoing corner loss,its angularity degree decreases and its shape tend to a sphere.Compared with cubic ballast particles,flaky and elongated ballast particles are more prone to degradation.The larger the size of ballast particle,the more prone to degradation.In comparing with Los Angeles abrasion test,the cyclic triaxial test can reveal more clearly the deterioration process of ballast because it is closer to the actual loading condition of ballast.

关 键 词：道砟劣化 大型动三轴试验 宏细观分析 三维激光扫描 图形分析法 

分 类 号：U213.722[交通运输工程—道路与铁道工程]