不同煤灰脏污程度下道砟宏观强度及细观颗粒转动特性分析  

Analysis of macroscopic strength and meso-scale particle rotation characteristics of railroad ballasts fouled by different levels of coal dust

作　　者：王萌 肖源杰 张冲冲[1] 杨涛 谭攀 卢明皎 WANG Meng;XIAO Yuanjie;ZHANG Chongchong;YANG Tao;TAN Pan;LU Mingjiao(School of Civil Engineering,Central South University,Changsha,Hunan 410075,China;MOE Key Laboratory of Engineering Structures of Heavy Haul Railway,Central South University,Changsha,Hunan 410075,China;School of Civil Engineering,Tongji University,Shanghai 200092,China)

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学重载铁路工程结构教育部重点实验室,湖南长沙410075 [3]同济大学土木工程学院,上海200092

出　　处：《岩石力学与工程学报》2024年第8期2027-2041,共15页Chinese Journal of Rock Mechanics and Engineering

基　　金：湖南省自然科学基金杰出青年基金项目(2024JJ2073);国家自然科学基金资助项目(52178443,51878673)。

摘　　要：道砟脏污易诱发有砟道床翻浆冒泥和差异沉降等病害,进而危及列车的平稳和安全运行。针对此工程难题,采用脏污指数(FI)配制不同煤灰脏污程度的道砟试样,开展室内大型单调加载三轴压缩试验,由试样内部不同位置处埋设的无线智能颗粒传感器(SmartRock)实时采集颗粒细观转动数据,分析不同煤灰脏污程度下道砟试样宏观剪切强度的变化规律及其与颗粒细观运动的关联机制。研究结果表明,煤灰脏污程度的增加在宏观上导致试样从应变硬化逐步过渡到应变软化;FI值为10%~15%时,试样峰值偏应力及似黏聚力值均最小;三轴试样内部道砟颗粒的转动主要表现为竖直面内的翻转,且清洁道砟试样内部颗粒在竖直面内的翻转随其距试样底部高度的下降而逐渐减弱,试样侧边缘对道砟颗粒运动的约束作用逐渐增强;当FI值达15%时,试样内部道砟颗粒的翻转无明显规律,或因颗粒间的传力骨架已逐渐被破坏;然而当FI值>15%时,试样内部道砟颗粒间的翻转运动差异性明显增大,致其力学稳定性降低;道砟颗粒转动的均匀性在一定程度上决定了其宏观强度性能,并可用于预估煤灰脏污程度。该研究成果或可为有砟道床煤灰脏污程度无损评定、清筛周期优化及智能养维提供理论依据和技术参考。Fouled ballast can commonly cause severe defects of ballasted trackbed including mud pumping and differential settlement,thus further endangering stable and safe operations of trains.To address this engineering challenge,ballast specimens with different fouling levels were prepared in the laboratory by adopting the classic fouling index(FI),and subsequently subjected to monotonic triaxial compression tests.The newly-invented wireless,self-powered and smart sensors(SmartRock)were placed at different positions inside ballast specimens to measure real-time particle rotation data.The macroscopic shear strength behaviors of ballast specimens with different fouling levels were analyzed comparatively and linked to meso-scale ballast particle movement.The results show that increasing coal dust fouling level could cause gradual transition of macroscopic behavior from strain hardening to strain softening.When the fouling index(FI)value ranges from 10%to 15%,both peak deviator stress at failure and apparent cohesion reach their minimums,respectively.The rotation of ballast particles inside the triaxial specimens mainly occurrs in the vertical planes,whereas the vertical-plane rotations of ballast particles located closer to the bottom of clean ballast triaxial specimens increasingly attenuate due to the increasing restraint of lateral boundaries on particle movement.When the FI value reaches 15%,no discernible rotation pattern is observed for ballast particles inside triaxial specimens,which may be attributable to the loss of inter-particle force-transferring skeleton.When the FI value further exceeds beyond 15%,ballast particle rotations exhibite significantly increasing differences,probably resulting in macroscopic mechanical instability.The uniformity of ballast particle rotations determines macroscopic shear strength behavior to a certain extent and thus can be employed to estimate the actual fouling level of ballast beds.The findings are expected to provide theoretical basis and technical reference for Non-destructive

关 键 词：路基工程 有砟道床 道砟脏污 单调加载三轴压缩试验 智能颗粒传感器 抗剪强度 颗粒转动 

分 类 号：U416[交通运输工程—道路与铁道工程]