Thermo-Hydro-Mechanical Coupling Characteristics of Fly Ash Subgrade in Condition of Unidirectional Freezing

doi:10.16552/j.cnki.issn1001-1625.2025.0454

Abstract

Abstract: Frost heave is a key factor contributing to subgrade damage in seasonally frozen regions. To investigate the changes of internal temperature, water content and frost heave force of fly ash subgrade in seasonally frozen areas, the one-dimensional soil column consolidation test equipment developed independently was used to carry out the unidirectional freezing test of fly ash column. A thermo-hydro-mechanical (THM) coupling model for fly ash subgrade was established to analyze the migration patterns of water and temperature, inside fly ash column and the change characteristics of frost heave force during the freezing process. The results show that the internal temperature changes of fly ash subgrade can be divided into three stages based on the cooling rate: rapid freezing, transitional freezing and steady freezing. As freezing time increases, the freezing front progressively descends, and a sharp water variation occurs at freezing front. Finite element software simulations effectively simulate the frost heave displacement and the transfer processes of temperature and water observed in the test. The specimen is divided into frozen zone, actively freezing zone and unfrozen zone. By the end of the test, the actively freezing zone significantly expands, while the frozen zone gradually stabilizes. The damage to the subgrade is characterized by the ice content during freezing process, showing that damage is primarily concentrated at the surface of the subgrade, and the closer to the interior of the subgrade, the smaller the damage degree. In this paper, the change of frost heave displacement of fly ash subgrade in long-term service in seasonal frozen area is simulated, and the mechanism of interaction between internal water content and temperature is explained.

Key words: seasonally frozen soil, fly ash, one-dimensional soil column, unidirectional freezing, thermo-hydro-mechanical (THM) coupling, ice content

CLC Number:

U416

HUI Yingxin, GU Shizhou, GUO Jukun, ZHENG Liyang, CHEN Wei, DONG Xuguang. Thermo-Hydro-Mechanical Coupling Characteristics of Fly Ash Subgrade in Condition of Unidirectional Freezing[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(11): 4048-4059.

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