高铁路基水泥粉煤灰填料冻融特性研究  

Study on freeze-thaw characteristics of cement fly ash filler for high-speed railway subgrade

作　　者：崔宏环 闫利[2] 赵嘉 CUI Honghuan;YAN Li;ZHAO Jia(Hebei Key Laboratory of Civil Engineering Diagnosis,Reconstruction and Disaster Resistance,Zhangjiakou 075000,China;Hebei University of Civil Engineering and Architecture,Zhangjiakou 075000,China)

机构地区：[1]河北省土木工程诊断、改造与抗灾重点实验室,河北张家口075000 [2]河北建筑工程学院,河北张家口075000

出　　处：《铁道科学与工程学报》2022年第10期2785-2793,共9页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(51878242);河北省教育厅重点资助项目(ZD2020325)。

摘　　要：为了研究高铁路基改良粗颗粒填料的冻融特性,采用粗粒土单向冻融试验装置开展高铁路基改良填料单向冻融试验。研究改良填料在冻融过程中受改良剂种类和改良剂掺量等因素影响,其内部温度、水分迁移、水分重分布和冻胀变形的变化规律,分析采用水泥和水泥粉煤灰改良后的粗颗粒填料的冻胀机理。试验结果表明:在单向冻结过程中,通过填料内部冻结深度变化可将填料冻结过程分为快速冻结、缓慢冻结和稳定冻结3个阶段,填料内部不同深度处的温度变化滞后于顶板温度变化;粉煤灰的掺入对水泥改良填料内部温度变化过程影响较小,但会减小填料的冻结深度;外部环境形成的温度梯度是填料内部水分迁移的驱动因素,2类填料冻结过程中内部水分向冻结锋面产生迁移,3次冻融循环后,冻结锋面所处深度含水率最高,距离冻结锋面越远,水分迁移作用越弱,体积含水率波动范围越小;水泥粉煤灰填料的毛细作用会导致填料持水能力增强,致使水泥粉煤灰填料在冻融过程中水分重分布现象较弱;2类改良后的填料均属于不冻胀类材料,其最大冻胀率均未出现在第1次冻结过程中,粉煤灰颗粒的存在会增大填料的冻胀敏感性,导致水泥粉煤灰填料的冻胀变形量高于水泥改良填料,且粉煤灰掺量越大,填料冻胀变形量越大。In order to study the freezing and thawing characteristics of coarse-grained filler for high-speed railway subgrade improvement,the unidirectional frost heaving test of high-speed railway subgrade improved filler was carried out by using the unidirectional frost heaving test device of coarse-grained soil.The change laws of internal temperature,water migration,water redistribution and frost heaving deformation of modified filler affected by the type and amount of modifier during freeze-thaw were studied,and the frost heaving mechanism of coarse-grained filler improved by cement and cement fly ash was analyzed.The test results show that in the unidirectional freezing process,the filling freezing process can be divided into three stages:rapid freezing,slow freezing and stable freezing through the change of freezing depth inside the filling.The temperature change at different depths inside the filling lags behind the temperature change of the roof;The addition of fly ash has little effect on the internal temperature change process of cement improved filler,but it will reduce the freezing depth of filler;The temperature gradient formed by the external environment is the driving factor for the internal water migration of the fillers.During the freezing process of the two types of fillers,the internal water migrates to the freezing front.After three freeze-thaw cycles,the depth moisture content of the freezing front is the highest.The farther away from the freezing front,the weaker the role of water migration and the smaller fluctuation range of volume moisture content;The capillary action of cement fly ash filler enhances the water holding capacity of the filler,resulting in the weak water redistribution of cement fly ash filler in the process of freeze-thaw;The two kinds of improved fillers belong to non frost heaving materials,and their maximum frost heaving rate does not appear in the first freezing process.The existence of fly ash particles increases the frost heaving sensitivity of fillers,resulting in the frost h

关 键 词：高铁路基 改良填料 温度场 水分迁移 水分重分布 冻融变形 

分 类 号：U214.11[交通运输工程—道路与铁道工程]