Thermal-hydraulic-mechanical coupling behavior and frost heave mitigation in freezing soil

Frost heave induced by artificial freezing can be destructive to infrastructure. The fundamental physicochemical mechanisms behind frost heave involve mainly the coupled thermal-hydraulic-mechanical (THM) behavior, ice-water phase transition, and heat and fluid flow in porous media. Taking the soil skeleton, pore ice, and pore water as independent bodies to conduct the mechanical analysis, we clarify the physical meaning of the effective stress principle of frozen soil with consideration of the multiphase interactions (ice-water-mineral) and further improve the coupled heat and fluid flow equations. Taking into account the coupled THM mechanism in freezing soils, a discrete ice lenses based model for frost heave is established with focus on segregation and growth of the ice lens. Upon validation of the frost heave model, an intermittent freezing method is applied to investigate mitigation of frost heave. Numerical results show that the intermittent freezing can significantly mitigate frost heave and inhibit the potential frost susceptibility of freezing soil. Our research reveals that the narrowing of the frozen fringe induced by the upward movement of the freezing front is the main reason for the slower growth of the ice lens. The THM behavior and heat and fluid flow based frost heave model enable a better understanding of the geomechanical properties of freezing soil and physical mechanism of frost heave mitigation in porous media (soil).