摘要
寒旱区封闭结构层工程构筑物在大温差作用下,水分在不透水面层底部聚集形成覆盖效应后加剧路基冻胀、融沉病害,但对长期时变环境作用下覆盖效应引起的路基内部水分累积过程、液态水与水汽输运规律,以及其与路基变形的关系尚不清楚。首先通过室内试验,验证了时变环境下季节冻土覆盖效应确实存在;然后基于非饱和土冻融过程中的液态水与水汽运移、相变过程和能量传递过程,建立了水汽热耦合分析理论模型;最后将验证后的模型应用于寒旱区某高等级公路宽幅路基,并对其内部水热输运进行了分析。结果表明:(1)室内冻融循环作用下,粉质黏土在冻深范围内含水率会随冻融循环次数的增加而增大,含水量的迁移量达6%;(2)季节温度变化导致水分向路基面层底部3 m范围内聚集,最大累积量达12%;(3)冻结期路基内部液态水和气态水向上迁移,导致路基上部的含水率增大,融化期则相反;(4)季节温度变化下,12月至次年的3月在路基上部1.5 m范围聚集的水分冻结成冰,最大冰含量可达16%,极易诱发路基冻胀破坏。
In the cold and arid regions, because of the effect of large temperature difference on the structures with closed structural layer, moisture accumulates at the bottom of impervious layer to form covering effect, which aggravates frost heaving and thawing settlement of subgrade. However, under the long-term time-varying environment, the relationship between the effect of large temperature difference and the process of moisture accumulation in subgrade, the law of liquid water and water vapor transport and the deformation of subgrade caused by covering effect is still unclear. In this paper, first of all, the existence of the cover effect of seasonal frozen soil under the time-varying environment is verified through indoor experiments. Then, a verified water-vapor-heat coupling theoretical model is established based on the transport, phase transition and energy transfer processes of liquid water and water vapor during the freezing and thawing process of unsaturated soil. Finally, the internal water and heat transports of a high-grade wide roadbed in a cold and arid area are analyzed by utilizing the verified water-vapor-heat coupling theoretical model.The results show that:(1)under the action of the indoor freeze-thaw cycle,the moisture content of silty clay in the freezing depth range will increase with the increase of the number of freeze-thaw cycles,with a maximum migration amount of 6%;(2)seasonal temperature changes cause moisture to accumulate within 3m of the bottom of the subgrade surface layer,with a maximum accumulation of 12%;(3)during the freezing period,the liquid water and gaseous water in the subgrade migrate upward,resulting in the increase of moisture content in the upper part of the subgrade,while the opposite in the melting period;and (4)under the change of seasonal temperature,the water accumulated in the upper 1.5m of subgrade freezes into ice from December to March of the next year,and the maximum ice content can reach 16%,which is easy to induce frost heaving damage of subgrade.
作者
钟黎
张瑞玲
张明礼
冯德刚
严艳锋
ZHONG Li;ZHANG Rui-ling;ZHANG Ming-li;FENG De-gang;YAN Yan-feng(Bridge and Tunnel Engineering Co.Ltd.,CCCC Third Highway Engineering Co.Ltd.,Beijing 10012,China;School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Geological Hazards Prevention Institute,Gansu Academy of Seiences,Lanzhou 730000,China)
出处
《公路》
北大核心
2022年第8期14-23,共10页
Highway
基金
国家自然科学基金项目,项目编号41961010、41861012
甘肃省基础研究创新群体项目,项目编号20JR5RA478
中交第三公路工程局有限公司技术服务项目,项目编号QSGS-YLTJ-4-JS-01-2019。
关键词
路基
季节冻土
覆盖效应
数值模拟
水分迁移
subgrade
seasonal frozen soil
covering effect
numerical simulation
vapor migration
