(1. Key Laboratory for Health Monitoring and Control of Large Structures in Hebei Province，Shijiazhuang Tiedao University，Shijiazhuang，Hebei 050043，China；2. State Key Laboratory of Frozen Soil Engineering，Cold and Arid Regions Environmental and Engineering Research Institute，Chinese Academy of Sciences，Lanzhou，Gansu 730000，China；3. School of Civil Engineering，Shijiazhuang Tiedao University，Shijiazhuang，Hebei 050043，China)
Abstract：An experimental apparatus was developed to study the water-heat-vapor migration characteristics of unsaturated coarse-grained filling of high-speed railway subgrade under freezing and thawing cycles，and a fluorescein tracer was used to trace the rising height and intake behavior of liquid water. A series of key technological experiments were conducted to validate the utility of the test method and the reliability of the apparatus，and freeze and thaw tests were performed to investigate the water-heat-vapor migration characteristics of unsaturated coarse-grained filling in a process of thrice freezing and twice thawing with 72 hours of the freezing time and 12 hours of the thawing time. The results indicate that under a constant temperature freezing mode，the frost penetration increases with increasing the freezing numbers. The external water infiltrates mainly in the form of vapor into the soil sample during freezing and the internal water comes out during thawing. The second freezing provides the maximum water intake. The ice accumulates on the top base pedestal and the increasing range of the water content in the frozen zone is relatively even at the end of the test. The water-vapor migration and phase change of the coarse-grained filling induced by freezing and thawing cycles could lead to an ice layer formation and a change in the strength of the high-speed railway subgrade.
[1] 李 强，姚仰平，韩黎明，等. 土体的“锅盖效应”[J]. 工业建筑，2014，44(2)：69–71.(LI Qiang，YAO Yangping，HAN Liming，et al. Pot-cover effect of soil[J]. Industrial Construction，2014，44(2)：69–71.(in Chinese))
[2] 姚仰平，王 琳，王乃东，等. 锅盖效应的形成机制及其防治[J]. 工业建筑，2016，46(9)：1–5.(YAO Yangping，WANG Lin，WANG Naidong，et al. Mechanism forming pot-cover effect and its prevention[J]. Industrial Construction，2016，46(9)：1–5.(in Chinese))
[3] NIU F J，LI A，LUO J，et al. Soil moisture，ground temperatures，and deformation of a high-speed railway embankment in Northeast China[J]. Cold Regions Science and Technology，2017，133：7–14.
[4] 张玉芝，杜彦良，孙宝臣. 季节性冻土地区高速铁路路桥过渡段路基变形特征分析[J]. 中国铁道科学，2016，37(1)：39–45.(ZHANG Yuzhi，DU Yanliang，SUN Baochen. Roadbed deformation characteristics of roadbed-bridge transition section for high speed railway in seasonal frozen soil region[J]. China Railway Science，2016，37(1)：39–45.(in Chinese))
[5] 张 升，贺佐跃，滕继东，等. 非饱和土水汽迁移与相变:两类“锅盖效应”的试验研究[J]. 岩土工程学报，2017，39(5)：961–968. (ZHANG Sheng，HE Zuoyue，TENG Jidong，et al. Water vapor transfer and phase change in unsaturated soils：experimental study on two types of canopy effect[J]. Chinese Journal of Geotechnical Engineering，2017，39(5)：961–968.(in Chinese))
[6] 徐敩祖. 国外对冻土中水分迁移课题的研究[J]. 冰川冻土，1982，4(3)：97–103.(XU Xiaozu. Research in the question of water migration in the permafrost abroad[J]. Journal of Glaciology and Cryopedology，1982，4(3)：97–103.(in Chinese))
[7] BOUYOUCOS G J. Effect of temperature on the movement of water vapor and capillary moisture in soils[J]. Journal of Agricultural Research，1915，5(4)：141–172.
[8] PHILIP J，VRIES D D. Moisture movement in porous materials under temperature gradients[J]. Transactions American Geophysical Unionbanner，1957，38(2)：222–232.
[9] 毛卫南，刘建坤. 冻土斜坡路基温度水分分布特性分析[J]. 铁道学报，2015，37(6)：88–94.(MAO Weinan，LIU Jiankun. Analysis of temperature and water content distribution of slope embankment in Permafrost regions[J]. Journal of the China Railway Society，2015，37(6)：88–94.(in Chinese))
[10] 李 杨，王 清，王坛华. 冻土水热耦合模型数值求解及结果检验[J]. 吉林大学学报：地球科学版，2015，45(1)：207–213.(LI Yang，WANG Qing，WANG Tanhua. Numerical solution and test of results for a hydrothermal coupled model about frozen soil[J]. Journal of Jilin University：Earth Science，2015，45(1)：207–213.(in Chinese))
[11] TENG J，SHAN F，HE Z，et al. Experimental study of ice accumulation in unsaturated clean sand[J]. Geotechnique，2019，69(3)：251–259.
[12] GAO J，LAI Y，ZHANG M，et al. Experimental study on the water-heat-vapor behavior in a freezing coarse-grained soil[J]. Applied Thermal Engineering，2018，128：956–965.
[13] BAI R，LAI Y，ZHANG M，et al. Water-vapor-heat behavior in a freezing unsaturated coarse-grained soil with a closed top [J]. Cold Regions Science and Technology，2018，155：120–126.
[14] ZHOU Z，MA W，ZHANG S，et al. Effect of freeze-thaw cycles in mechanical behaviors of frozen loess[J]. Cold Regions Science and Technology，2018，146：9–18.
[15] 穆彦虎，马 巍，李国玉，等. 冻融作用对压实黄土结构影响的微观定量研究[J]. 岩土工程学报，2011，33(12)：1 919–1 925.(MU Yanhu，MA Wei，LI Guoyu，et al. Quantitative analysis of impacts of freeze-thaw cycles upon microstructure of compacted loess[J]. Chinese Journal of Geotechnical Engineering，2011，33(12)：1 919–1 925.(in Chinese))
[16] EIGENBROD K D，KENNEPOHL G J A. Moisture accumulation and pore water pressures at base of pavements[J]. Transportation Research Record：Journal of the Transportation Research Board，1996，1546：151–161.
[17] 中华人民共和国行业标准编写组. TB 10001—2016铁路路基设计规范[S]. 北京：中国铁道出版社，2017.(The Professional Standards Compilation Group of the People′s Republic of China. TB 10001—2016 Code for design of railway earth structure[S]. Beijing：China Railway Publishing House，2017.(in Chinese))
[18] 中华人民共和国行业标准编写组. TB 10102—2010铁路工程土工试验规程[S]. 北京：中国铁道出版社，2010.(The Professional Standards Compilation Group of the People′s Republic of China. TB 10102—2010 Codes for soil test of railway engineering[S]. Beijing：China Railway Publishing House，2010.(in Chinese))
[19] 吴 镇，岳祖润，王天亮. 哈齐客专细圆砾土冻结温度测试分析[J]. 石家庄铁道大学学报：自然科学版，2013，26(1)：37–40.(WU Zhen，YUE Zurun，WANG Tianliang. Test analysis on freezing temperature of fine round gravel soil in Harbin-Qiqihaer Railway[J]. Journal of Shijiazhuang Tiedao University：Natural Science，2013，26(1)：37–40.(in Chinese))
[20] ARENSON L U，SEGO D C. The effect of salinity on the freezing of coarsegrained sands[J]. Canadian Geotechnical Journal，2006，43(3)：325–337.
2020, Vol. 39 
