疲劳荷载作用下无砟轨道混凝土钙溶蚀特性  

Calcium Dissolution Properties of Ballastless Track Concrete under Fatigue Load

作　　者：杨荣山[1,2] 仪皓楠 康维新 曹世豪[1,2] YANG Rongshan;YI Haonan;KANG Weixin;CAO Shihao(Key Laboratory of High-speed Railway Engineering of Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学高速铁路线路工程教育部重点实验室,四川成都610031 [2]西南交通大学土木工程学院,四川成都610031

出　　处：《铁道学报》2025年第2期160-171,共12页Journal of the China Railway Society

基　　金：国家自然科学基金(52272442,52278459)。

摘　　要：无砟轨道结构在多雨地区或排水不畅地段会出现混凝土层间冒浆现象,该现象主要由力学损伤与化学溶蚀共同引起,其中钙溶蚀是化学溶蚀的主要形式之一。通过对现场冒浆采集物进行化学成分测定,证实水环境下混凝土的钙溶蚀现象,开展疲劳荷载下的无砟轨道混凝土钙溶蚀试验,采用原子吸收分光光度计测试混凝土溶蚀过程中的钙离子溶出量,采用钨灯丝电镜(SEM)结合面扫描能谱仪(EDS)测定混凝土微观结构分布与钙元素占比,基于钙离子溶出量与氧化钙含量计算试件的溶蚀率和溶蚀深度。测试溶蚀后混凝土表面平均强度,分析钙溶蚀深度对混凝土表面强度的影响。结果表明:疲劳荷载不改变C15、C40混凝土的溶蚀模式,但会加快钙溶蚀的发展速率;对于C15混凝土,累计钙溶出量与时间成正比,疲劳荷载作用下溶蚀速率提升了127.5%,对于C40混凝土,累计钙溶出量与时间平方根成正比,疲劳荷载作用下溶蚀速率提升了68.9%;钙溶蚀会明显削弱混凝土表面的抗压强度,C15混凝土在有、无疲劳荷载作用下加速溶蚀7 d后,平均表面抗压强度损失分别为57.5%、40.6%,C40在有、无疲劳荷载作用下加速溶蚀7 d后,混凝土平均表面抗压强度损失分别为56.2%、43.9%。Ballastless track structures are subject to concrete interlayer mud-pumping under the long-term effects of train loads and environmental factors,which is mainly caused by mechanical damage and chemical dissolution,with calcium dissolution being one of the main forms of the chemical dissolution.The chemical composition of mud-pumping collected from the site was determined to confirm the calcium dissolution in concrete under water environment.Calcium dissolution tests were carried out on ballastless track concrete under fatigue loading.Calcium ion dissolution during concrete dissolution was measure using an atomic absorption spectrophotometer.The microstructural distribution of concrete and the proportion of calcium elements were determined using a scanning electron microscope(SEM)combined with an energy dispersive spectrometer(EDS).The dissolution rate and depth of dissolution of the specimens were calculated on the basis of calcium ion dissolution and calcium oxide content.With the average strength of the concrete surface after dissolution being tested,the effect of the depth of calcium dissolution on the concrete surface strength was analyzed.The results show that fatigue loading does not change the dissolution pattern of C15 and C40 concrete,but accelerates the rate of development of calcium dissolution.For C15 concrete,the cumulative calcium leaching is proportional to time,with the rate of leaching increasing by 127.5%under fatigue loading.For C40 concrete,the cumulative calcium leaching is proportional to the square root of time,with the rate of leaching increasing by 68.9%under fatigue loading.Calcium leaching significantly weakens the compressive strength of the concrete surface,with average surface compressive strength losses of 57.5%and 40.6%for C15 concrete after 7 d of leaching with and without fatigue loading,and 56.2%and 43.9%for C40 concrete after 7 d of leaching with and without fatigue loading,respectively.

关 键 词：无砟轨道 列车荷载 冒浆 钙溶蚀 

分 类 号：U213.244[交通运输工程—道路与铁道工程]