相变黏土单向冻融作用下冻胀特性的试验研究  

Experimental study on frost heave characteristics of PCM-clay under one-dimensional freeze-thaw

作　　者：王泽帆 刘东海[1] 岳雪琴 杨家琦 WANG Zefan;LIU Donghai;YUE Xueqin;YANG Jiaqi(State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation,Tianjin University,Tianjin 300354,China)

机构地区：[1]天津大学水利工程智能建设与运维全国重点实验室,天津300354

出　　处：《岩土工程学报》2025年第4期705-714,共10页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金面上项目(5227090128)。

摘　　要：掺混相变材料(PCM)的相变黏土以其防冻控温的特性,使黏土心墙、渠道、坝堤、道路等场景下的负温施工成为了可能。针对冬季施工现场日循环冻融作用的环境特点,在室内模拟开展封闭系统、分段控温、浅冻结条件下的单向冻融试验,研究相变黏土冻胀特性及在冻融循环作用下冻胀发育规律及机理。结果表明:相变黏土的冻胀特性较不掺混PCM的黏土(素土)得到了改良,经历冻融循环后,相变黏土的最终冻胀量远小于相同冻融循环次数下的素土试样,且土料的冻结锋面下移速率及水分迁移程度降低;多次冻融循环后,素土的冷生构造产生了更为显著的发育,而相变黏土未表现出明显的冻胀敏感性,冷生构造的形成和发育都非常缓慢。分析认为,初始饱和度较低、孔隙较大以及PCM的高潜热储能、冻缩性、阻水性等是使相变黏土冻胀特性得到改良的主要原因。研究可为相变黏土作为潜在大坝心墙、渠道、坝堤、道路的建设材料提供寒区冬季施工防冻提供了理论依据。The clay incorporated with phase change material(PCM-clay)has the characteristics of freezing resistance and temperature control,which makes it possible to construct clay core walls,channels,embankments,roads and other scenarios with negative temperature.According to the environmental characteristics of daily cyclic freeze-thaw effects on the construction site in winter,a series of repeated one-dimensional freeze-thaw experiments under closed system,step thermoregulation and shallow freezing conditions in a closed system are simulated indoors to study the frost heave characteristics of the PCM-clay and the law and mechanism of frost heaving development under the action of freeze thaw cycles.The results show that the frost heave characteristics of the PCM-clay is improved compared with that of the clay without PCM(pure clay).After freeze-thaw cycles,the final frost heaving amount of the PCM-clay is far less than that of the pure clay under the same freeze-thaw cycles.The downward moving rate of soil freezing front and the degree of moisture migration also decrease.After several freeze-thaw cycles,the cryogenic structure of the pure soil has developed more significantly,while the PCM-clay does not exhibit obvious frost heave sensitivity,and the formation and development of cryogenic structure are very slow.The analysis shows that the low water content,large porosity,high latent heat energy storage,freezing shrinkage and hydrophobicity of the PCM are the main reasons for improving the frost heave characteristics of the PCM-clay.This study can provide a theoretical basis for the PCM-clay as a construction material for potential dam core walls,channels,embankments,and roads to provide winter construction frost protection in cold regions.

关 键 词：负温施工 相变黏土 冻融循环 冻胀特性 相变材料 

分 类 号：TU41[建筑科学—岩土工程]