Uneven frost heave deformation can shorten the operational lifespan of foundation engineering. Clarifying the mechanisms of uneven frost heave facilitates the targeted mitigation of frost damage. This study focused on a water conveyance channel in Jilin Province, northern China, and found after monitoring that the frost heave at the channel bottom lining exceeded that at the crest by 44.5 mm, with the freezing temperature at the bottom being over 2 degrees C lower than that at the crest. Soil columns with an initial gravimetric moisture content of 12%, 16%, 18%, and 20% were then prepared. The effects of temperature and moisture content on frost heave were analyzed under two freezing conditions (-5 degrees C and-10 degrees C) through unidirectional freezing tests. A coupled thermo-hydro-mechanical (THM) frost heave model, validated by the test results, was further established. In the soil with an initial moisture content of 20%, the formation of ice lenses associated with substantial water migration contributed to a large temperature gradient, which can jointly induce frost heave. Under the-10 degrees C condition, the temperature gradient in the soil column with a 20% initial moisture content reached 0.84 degrees C/cm, the total water migration reached 10.72%, and the frost heave deformation was 1.86 mm. The THM coupling results indicated that, under the interaction of a large temperature gradient and moisture accumulation, the volumetric ice content remained high in the bottom soil during freezing and peaked at 0.36. The frost damage to the bottom soil was severe, and the maximum deformation reached 57 mm. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).