季节冻土路基覆盖效应换填控制效果研究  

Research on the Control Effect of Subgrade Covering Effect on Seasonally Frozen Soil

作　　者：马浪 张瑞玲[2] 张明礼[2,3] MA Lang;ZHANG Ruiling;ZHANG Mingli(Bridge and Tunnel Engineering Co.,Ltd.,CCCC Third Highway Engineering Co.,Ltd.,Beijing 100012,China;School of Civil Engineering,Lanzhou University of Technology,Lanzhou 730050,China;Geological Hazards Prevention Institute,Gansu Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]中交三公局桥梁隧道工程有限公司,北京100012 [2]兰州理工大学土木工程学院,甘肃兰州730050 [3]甘肃省科学院地质自然灾害防治研究所,甘肃兰州730000

出　　处：《甘肃科学学报》2023年第3期113-120,共8页Journal of Gansu Sciences

基　　金：甘肃省高等学校产业支撑计划项目(2020C-40)。

摘　　要：季节冻土区的覆盖效应会导致路基内部发生水分迁移从而引起路面产生冻胀开裂及融沉塌陷等病害。采用非饱和土体水汽热耦合模型,重现了粉质黏土路基覆盖效应的形成过程,模拟了砂土换填法处理季节冻土区路基覆盖效应的效果。研究结果表明:(1)对于未换填的粉质黏土路基填料,覆盖效应作用下液态水和水汽在冬春季节向路基表层迁移,夏秋季节向路基内部迁移,水分在路基表层近1 m的范围内聚集,含水率的最大增加量达18%;(2)换填后的砂土路基相比于未换填的粉质黏土路基其冻结深度更深,液态水和水汽迁移通量减小。换填后的路基在覆盖效应作用下水分迁移量在换填深度内减少,含水率的累积变化值比未换填的路基小26%。因此,将路基一定深度范围内的粉质黏土填料换填为砂土填料可以防治由于覆盖效应所引起的表层含水率的增加。The covering effect produced in the seasonally frozen soil area will cause the water migration inside the roadbed,which will further trigger road surface to generate frost heaving cracking,melting subsidence and other engineering disasters.In the present work,a numerical model describing fully coupled water vapor and heat transfer in unsaturated soils has been established to reproduce the formation process of the covering effect in subgrade and simulate the advantages of sand replacement method to treat the subgrade covering effect in seasonal frozen soil area.The results show that for the original subgrade filled with silty clay,the covering effect will cause liquid water and water vapor to migrate to the surface of the subgrade in winter and spring,and migrate to the inside of the subgrade in summer and autumn.Moreover,the moisture accumulates in the range of nearly 1m on the subgrade surface,and the maximum increase of moisture content can reach 18%.Compared to the original subgrade completely filled with silty clay,after the subgrade soil is partially replaced with sand,the freezing depth of subgrade is deeper,and the migration flux of liquid water and water vapor is reduced apparently.In this case,the covering effect is significantly weakened,which is specifically manifested in the reduction of the water accumulation within the replacement depth and the decrease of the cumulative change in water content.Therefore,replacing silty clay with sand within a certain depth of subgrade is an effective preventive measure for the covering effect.

关 键 词：季节冻土 覆盖效应 含水率 换填土体 数值模拟 

分 类 号：TU43[建筑科学—岩土工程]