基于多物理场耦合的双块式无砟轨道早期混凝土时变行为研究  

Time Varying Behavior of Early-age Concrete of Double-block Ballastless Track Based on Multi-physical Field Coupling

作　　者：李潇[1,2] 刘伟 任娟娟[1] 杨荣山[1] 刘学毅[1] LI Xiao;LIU Wei;REN Juanjuan;YANG Rongshan;LIU Xueyi(MOE Key Laboratory of High-speed Railway Engineering,Southwest Jiaotong University,Chengdu 610031,China;China MCC5 Group Corp.Ltd.,Chengdu 610063,China;School of Transportation Engineering,Tongji University,Shanghai 201804,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]中国五冶集团有限公司,四川成都610063 [3]同济大学交通运输工程学院,上海201804

出　　处：《铁道学报》2023年第5期91-102,共12页Journal of the China Railway Society

基　　金：国家重点研发计划(2021YFB2600900,2021YFF0502100);国家自然科学基金(52022085,52278461);四川省科技计划(2022JDTD0015)。

摘　　要：针对无砟轨道道床混凝土早期开裂问题,基于多物理场耦合理论,提出一种适用于浇筑早期的双块式无砟轨道水化-热-湿-力耦合计算模型,利用既有试验验证模型合理性,获取无砟轨道道床早期各物理场的时空分布规律,进行开裂风险预测。结果表明,与试验结果对比,本文模型对早期混凝土各物理场的模拟较为合理,尤其对表面干燥下的湿度场、复杂应力场的计算具有较强的适用性;道床水化速率先迅速增大后逐渐减,至第7 d基本停滞,最大水化速率出现在浇筑后约7 h,不同深度的水化度发展一致;受水化热影响,浇筑后24 h道床温度呈升高趋势,后受环境影响程度增大,随环境温度呈日周期变化;道床相对湿度及含水量呈垂向梯度分布,支承层对道床底部的干燥作用较为明显,水化耗水是导致道床内含水量降低的主要因素;道床早期应力及开裂风险呈周期性变化,最大开裂风险达到1.0,位于轨枕与道床的结合面处,并预测了道床早期开裂的3种主要形式。Aiming at the problem of early cracking of ballastless track bed concrete,based on the multi-physical field coupling theory,a calculation model of chemo-thermo-hygro-mechanical coupling for double-block ballastless track was proposed.The rationality of the model was verified by the existing tests,and the temporal and spatial distribution law of each physical field in the early stage of ballastless track bed was obtained to predict the cracking risk.The simulation results show that the model is reasonable for the physical field simulation of early-age concrete,especially for the calculation of moisture field under dry surface condition and stress field under complex stress state.The hydration rate of the track bed increases rapidly at first before decreasing gradually,until it basically stops on the 7th day.The maximum hydration rate occurs about 7 hours after pouring,and the development of hydration degree at different depths is consistent.Affected by the heat of hydration,the temperature of the track bed rises 24 hours after pouring,which is increasingly affecterd by the environment,and changes with the environment temperature in a daily cycle.The relative humidity and moisture content of the track bed are distributed in vertical gradient,with obvious drying effect of the supporting layer on the bottom of the track bed.The hydration water consumption is the main factor leading to the decrease of the moisture content of the track bed.The early-age stress and cracking risk of the track bed change periodically,with the maximum cracking risk reaching 1.0,which is located at the joint surface of the sleeper and the track bed.Three main forms of early-age cracking of the track bed are predicted.

关 键 词：无砟轨道 早期混凝土 开裂风险 时变行为 多物理场耦合 

分 类 号：U213.21[交通运输工程—道路与铁道工程]