Coupled heat and salt transport in engineered geomaterials and subsurface systems: Theory, model, and engineering implications

This paper presents a state-of-the-art review on the recent theories and models for the coupled heat and salt transport, i.e., thermohaline transport (THT), in engineered geomaterials and subsurface systems. The primary progress in simulating coupled THT in soils under both positive and subzero temperature conditions is discussed, with the critical role of water phase transitions in driving THT emphasized. Furthermore, existing theories and models for describing THT in both rock matrices and fractures are systematically categorized, highlighting the significant influence of fractures on THT, which, however, has been less discussed before. The potential applications of THT in various engineering are outlined, clarifying the pivotal role of THT mechanisms in addressing challenges across these engineering. Finally, this paper identifies key future research directions for advancing coupled THT theories to resolve critical geo-engineering challenges, including the influence of porosity variations on THT in geomaterials, fracture-dominated THT interactions, the impact of THT on the efficiency of subsurface operations associated with salt transfer, and the need for conducting experimental studies to validate and improve the performance and accuracy of the existing THT models.