Thawing-consolidation performances of frozen soil in segregated ice-rich regions using thermo-hydro-mechanical coupled model

Detailing the phase change and migration mechanism of segregated ice in frozen soil is crucial to predict the complex variation in thawing frozen soil. In this study, a thawing-consolidation model based on thermo-hydromechanical coupling method was developed to describe the variation of temperature, water migration and settlement process in the thawing froze soil of ice-rich regions. The abundant underground water environment experimental system was set up to replicate the authentic conditions. The permeability expression of melting segregated ice based on the measurements was included in the developed model, and the Terzaghi theory was introduced to describe the consolidation characteristics in mechanical equilibrium function. The superiority of the developed model was stated comparing with the traditional model, and the relative errors between measurement and developed model in temperatures, water contents and settlements were 0.24 %, 4.8 %, and 12.6 %, respectively. The thawing fronts, water contents, water gradients and settlements of frozen soil were then detailed with the variation of upper surface soil temperatures, initial water contents, and particle sizes. The results showed that the melting fronts were sensitive to the variation of upper surface temperature which accelerated the melting process of segregated ice. The initial water contents (0.18 to 0.24) extended the phase change process from 3.7 h to 6.8 h and decreased the water gradient at 0 m from 0.61 x 10 -7 m/s to -0.59 x 10 - 7 m/s. The increase in particle size (0.013 mm to 0.150 mm) decreased the settlements from -3.1 x 10 -3 m to -9.8 x 10 -3 m. Moreover, based on the deduction of void ratio in model, the variation of pore pressure in thawing soils could also be elaborated.