While numerous models exist for soil evaporation estimation, they are more or less empirically based either in the model structure or in the determination of introduced parameters. The main difficulty lies in representing the water stress factor, which is usually thought to be limited by capillarity‐supported water supply or by vapor diffusion flux. Recent progress in understanding soil hydraulic properties, however, have found that the film flow, which is often neglected, is the dominant process under low moisture conditions. By including the impact of film flow, a reexamination on the typical evaporation process found that this usually neglected film flow might be the dominant process for supporting the Stage II evaporation (i.e., the fast falling rate stage), besides the generally accepted capillary flow‐supported Stage I evaporation and the vapor diffusion‐controlled Stage III evaporation. A physically based model for estimating the evaporation rate was then developed by parameterizing the Buckingham‐Darcy's law. Interestingly, the empirical Bucket model was found to be a specific form of the proposed model. The proposed model requires the in‐equilibrium relative humidity as the sole input for representing water stress and introduces no adjustable parameter in relation to soil texture. The impact of vapor diffusion was also discussed. Model testing with laboratory data yielded an excellent agreement with observations for both thin soil and thick soil column evaporation experiments. Model evaluation at 15 field sites generally showed a close agreement with observations, with a great improvement in the lower range of evaporation rates in comparison with the widely applied Priestley and Taylor Jet Propulsion Laboratory model.

The interface between soil and concrete in cold climates has a significant effect on the structural integrity of embedded structures, including piles, liners, and others. In this study, a novel temperature control system was employed to conduct direct shear tests on this interface. The test conditions included normal stress (25 to 100 kPa), temperature (ranging from 20 to −6 °C), water content (from 10 to 19%), and shear rates (0.1 to 1.2 mm/min). Simultaneously, the deformation process of the interface was continuously photographed using a modified visual shear box, and the non-uniform deformation mechanism of the interface was analyzed by combining digital image correlation (DIC) technology with the photographic data. The findings revealed that the shear stress–shear displacement curves did not exhibit a discernible peak strength at elevated temperatures, indicating deformation behavior characterized by strain hardening. In the frozen state, however, the deformation softened, and the interfacial ice bonding strength exhibited a positive correlation with decreasing temperature. When the initial water content was 16% and the normal stress was 100 kPa, the peak shear strength increased significantly from 99.9 kPa to 182.9 kPa as the test temperature dropped from 20 °C to −6 °C. Both shear rate and temperature were found to have a marked effect on the peak shear strength, with interface cohesion being the principal factor contributing to this phenomenon. At a shear rate of 0.1 mm/min, the curve showed hardening characteristics, but at other shear rates, the curves exhibited strain-softening behavior, with the softening becoming more pronounced as shear rates increased and temperatures decreased. Due to the refreezing of interfacial ice, the residual shear strength increased in proportion to the reduction in shear rate. On a mesoscopic level, it was evident that the displacement of soil particles near the interface exhibited more pronounced changes. At lower shear rates, the phenomenon of interfacial refreezing became apparent, as evidenced by the periodic changes in interfacial granular displacement at the interface.

In seasonally frozen ground, there are many frost problems in highway road tunnel after its excavation due to the heat exchange between the cold air and lining structure inside the tunnel. To mitigate these frost‐related damages, thermal insulation layer is widely used at entrance and exit sections of the tunnel. In this study, a coupled mathematical model of heat, moisture, and stress was built for tunnels in seasonally permafrost regions. Then, based on the field‐observed air temperature inside a roadway tunnel at Altun Mountain on the Qinghai‐Tibet Plateau (QTP), seasonal freeze‐thaw process of the surrounding rocks (SR) and lining structures were numerically investigated with the consideration of insulation methods: without insulation (WTIL) and laying the insulation layer on the inner surface of the second lining structure (STIL). Combined with the principle of Miner damage accumulation, the stress regimes of the lining structures of tunnel were investigated in WTIL and STIL. The results show that there was a significantly thermal disturbance of the SR after the tunnel excavation. In the 5^th year of the operation period, the maximum seasonal freeze depth (MSFD) of the SR can reach 1.6 m at the vault of the arch and that at the inverted arch was only 1.0 m due to the pavement inside the tunnel. Then, both the absolute maximum value of the maximum principal stress (MAPS) and minimum principal stress (MIPS) in cold season were bigger than those in warm season comparing the value of the stress filed of the lining structure. In the same way, both the MAPS and MIPS of the lining structure in WTIL are bigger than those in STIL in numerical simulation. The positions of the maximum tensile stress of the primary lining structure in STIL and WTIL were inverted arch. For the lining structures, the greater tensile stress was generally harmful. Thus, the inverted arch of the tunnel should be laid on the insulation layer.

In this article, changes of pore water pressures (PWP) in silty clay subjected to freezing and thawing were measured under an open‐system condition. A total of five soil samples were tested, with water contents of 10.70%, 18.28%, 23.98%, 31.00%, and 37.65%, respectively. Each experienced a first‐step freezing stage, a thawing stage, and a second‐step freezing stage. The results showed that changes in PWP depended on the water content, soil type, salinity, ice content, air, pressure, temperature, and others. The PWP minimum with initial water content has a “w‐shaped double‐valley” characteristic, which described two PWP minima existing in two optimum water contents as initial water content increased. An influence‐factor analysis of PWP was proposed and gave a reasonable interpretation on the “w‐shaped double‐valley” characteristic of PWP. In addition, the tensiometer method to measure PWP in frozen soil was further discussed with regard to its advantages and disadvantages.