Journal of Cold Regions Engineering

This paper presents the results of snow load calculations in Alaska based on measurements of snow depth and snow water equivalent from 1950 to 2017 acquired from the Global Historical Climate Network (GHCN). After cleaning and validation of data, snow depth and snow water equivalent values were analyzed to find the best statistical distribution using several numerical criteria and visual assessment of the best fit. The best-fit distributions were then compared with the lognormal distribution and used to calculate the 50-year mean recurrence intervals. The relationships between snow depth and snow water equivalent were analyzed. Regression models were built for both the best-fit and lognormal distributions. Finally, these regression equations were used to estimate snow water equivalent for stations where only snow depth was recorded.

This study deals with the susceptibility to convective heat transfer of the materials used in the Finnish rail network. Previous studies have found that convection clearly influences the thermal conductivity of coarse aggregates in certain conditions. The occurrence of convection may cause subsoil frost heave. This study investigated the susceptibility of three subballast materials, which were made of different crushed rock aggregates, to convection: railway ballast (31.5/63 mm), subballast layers of crushed rock, and 5/16 mm crushed rock. Convection was found to increase the thermal conductivity of railway ballast severalfold, while the thermal conductivity of the currently used subballast material was also noted to increase clearly when the moving medium contained water. However, no significant increase in thermal conductivity was found in the case of the 5/16 mm crushed rock. Based on these results, it is clear that it is not possible to use tremendously coarse materials in thick structure layers in the northern area. The results of this study were one of the most important factors when the grading recommendation for subballast material used in Finland was changed to include finer material, which clearly reduces the possibility of the onset of convection.

Unfrozen water is a critical component of frozen soil that determines its thermal and mechanical behavior and affects engineering structures during freeze–thaw cycles. Here, pulsed nuclear magnetic resonance was used to investigate the behavior of unfrozen water in silty clay, medium sand, and fine sand soils with different initial water contents and dry densities during freezing and thawing. An integral form was derived based on the capillary theory and the Gibbs–Thomson equation to estimate the unfrozen water content in unfrozen pores during freezing. The unfrozen water content in frozen pores was then calculated using the thickness of an adsorbed thin water film and the Clapeyron equation. A mathematical physical model was established based on similarity theory to obtain curves relating the temperature and unfrozen water content during thawing. The model was validated using experimental data and data from previous studies. The unfrozen water content is highly dependent on the dry density and soil type; all curves showed hysteresis during freezing and thawing owing to the different thermodynamic potentials of pore water.

Frost heave of soil is a highly nonuniform problem, in which the local deformation is much more severe and meaningful compared with the overall deformation. When soil is upon freezing, a water–ice phase change occurs and induces the migration of pore water. Subsequently, the distribution of temperature, water content, ice content, and fabric is highly nonuniform in frozen soil. The local frost deformation of soil mainly depends on the local temperature, soil water content, and ice content. In this study, the particle image velocimetry (PIV) method is introduced into the soil column test to monitor the local frost deformation. Several tracer particles are tested to overcome the difficulty that the deformation field is not clear in clay soil. The results demonstrate that the mixed sand is a suitable choice of tracer particles and can lead to clear contours of vertical displacement and strain. Such local deformation information is valuable and can be synthetically analyzed with the local temperature, soil water content, and ice content. The PIV technique is considered to be a good choice for monitoring the local frost deformation field in frozen soil.

This article is devoted to the calculation and optimization of the engineering protection of cold underground condensate pipelines using heat-tracing cable in frost-susceptible soils in Western Siberia. The method for stress–strain state calculation of a pipeline in frost-susceptible soils has been developed. The dependence of maximal stresses in the pipeline wall on the linear heat-generation rate of the heat-tracing cable in the case of a constant heating mode has been derived. The dependence shows a monotonic decrease of maximum displacement of the pipeline and stresses in the pipeline wall with an increase of the linear heat-generation rate. The influence of a startup delay of the heat-tracing cable to the stress–strain state of the pipeline has been numerically investigated. The use of heating mode with delayed startup reduces the electrical energy consumption by 35.4% for considered pipeline comparing a constant heating mode due to fast soil freezing around a pipeline at the initial stage. The effect of energy saving depends on the linear heat-generation rate of the heat-tracing cable. For the considered pipeline, heat-tracing cable with a minimum permissible linear heat-generation rate of 1 W · m⁻¹ and 3.5 years startup delay provides maximum energy savings.

Thermal performance of an insulation material is influenced by the in-service temperature condition. Unlike most other insulation materials, thermal resistance (R-value) of polyisocyanurate (polyiso or PIR) foam insulation with “captive blowing agent” varies nonlinearly with temperature. Building designers consider the constant R-value of different insulating materials for building design and energy calculations, and hygrothermal simulation software tools, such as WUFI, consider the linear temperature-dependent R-value, even for polyiso. However, neither the linear temperature-dependent thermal resistance nor the constant thermal resistance value of polyiso represents the actual thermal performance. This paper aims to quantify the impact of in-service boundary temperature conditions in Canadian climates on the thermal performance of polyiso foam insulation board used in EPDM and PVC roof constructions. Hygrothermal simulations were performed using WUFI Pro, which considers real climate data and hygrothermal properties of constituent roof components for evaluating moisture and temperature conditions in roof constructions. Based on heating degree days (HDD), ten different cities were selected between climate Zone 4 (HDD < 3,000) and Zone 8 (HDD ≥ 7,000). The thermal resistance measurements were conducted using heat flow meter apparatus on four polyiso insulation boards (two new and two aged) of different sizes [thickness, new: 1 in. (25 mm) and 2 in. (51 mm); aged: 2 in. (51 mm) and 3 in. (76 mm)] at five mean temperatures of −4°C (25°F), 4.5°C (40°F), 10°C (50°F), 24°C (75°F), 43°C (110°F), and at a temperature differential of 28°C (50°F). The measured thermal resistance data of the four samples at different mean temperatures were normalized with calculated thermal resistance of each sample at 22°C (72°F). The normalized R-value variation was calculated using in-service boundary temperature conditions determined from hygrothermal simulations and considering linearly varied thermal resistance with temperature, for the selected ten Canadian cities. The normalized R-value data of four polyiso samples revealed 17.4% decrease in R-value under winter conditions of Zone 8.

Organosilane (OS) is a silicon-based coupling agent capable of producing hydrophobicity in soils. This study evaluated the applicability of OS in reducing the freeze–thaw impacts on subgrade soils. A frost-susceptible soil was treated with two different dosages (50% and 100% by weight) of 10% OS solution. The OS-treated soils were dried and incorporated into natural soil as layers of 2.5 and 5 cm thickness. The freeze–thaw performances of natural and OS-incorporated soils were then evaluated in terms of maximum frost heave, heave rate, soil moisture distribution, and temperature profile. The OS-treated soil layers decreased frost heaving by 48%–74%. The heave rate of untreated soil was 13.8 cm/day, which was decreased to 4 mm/day with an incorporation of 5 cm-thick layer of 50% OS-treated soil. A 5 cm–50% OS-treated layer was found to be more efficient compared to a 5 cm–100% OS-treated layer in improving the freeze–thaw performance of the soils.

A thermo-hydro-mechanical (THM) coupling model that considers phase transition and frost heaving was developed for a diversion tunnel in a seasonally frozen region. Based on the partial differential equation defined by COMSOL software, a numerical simulation of the temperature field, the seepage field, and the stress field of the rock surrounding the tunnel was conducted. The distributions of temperature, pore-water pressure, and frost heave deformation were also analyzed. The results indicated that the temperature of the surrounding rock periodically changes with changes in the seasonal environmental temperature. Due to the superposition effect of the environment temperature in the tunnel and at the ground surface, the maximum radial frozen depth of the tunnel during the freezing period is the highest at the top of the tunnel, whereas it is at its lowest at the bottom of the tunnel. The maximum radial frozen depth of the tunnel side and bottom tends to be the same because the maximum negative temperature decreases, the specific heat capacity increases, or the heat conductivity decreases. Before freezing, the fissure water in the surrounding rock is smoothly discharged along the ground surface and in the tunnel, and the water supply and drainage of the surrounding rock are basically maintained in an equilibrium state. During freezing, the fissure water in the unfrozen zone is in a state of overpressure due to the failure of the drainage channel in the frozen zone, and the frozen zone changes from a saturated state to an unsaturated state. The lower the maximum negative temperature, the greater the negative pore-water pressure in the frozen zone. The maximum frost heave displacement of the ground surface occurs at the top of the tunnel; however, because the distance from the top of the tunnel increases, the frost heave effect of the tunnel gradually decreases.

This study investigated the effect of cold temperatures on impact resistance and mechanical properties of a number of self-consolidating and vibrated concretes. Different mixture compositions were developed and tested under compression, four-point bending, and drop-weight impact loading. All tests were conducted at four different temperatures: +20°C, 0°C, −10°C, and −20°C. The studied variables were supplementary cementing materials (SCMs) [including fly ash (FA), slag (SL), silica fume (SF), and metakaolin (MK)]; the nominal maximum coarse aggregate size (10 and 20 mm), coarse-to-fine (C/F) aggregate ratio (0.7 and 2), and binder content (250 and 500 kg/m³). In addition, 35-mm steel fibers were introduced in one self-consolidating concrete (SCC) mixture for comparison. The experimental results indicated that the compressive strength, flexural strength, and impact resistance of all developed mixtures were generally improved as the temperature decreased. These improvements were more pronounced in mixtures with a relatively low binder content of 250 kg/m³ and mixtures with a higher C/F aggregate ratio. On the other hand, the lowest improvements were observed in higher strength mixtures and mixtures with more reactive SCMs such as SF or MK. Colder temperatures also boosted the role of fibers in improving the flexural strength and impact resistance of concrete.

The artificial freezing technology is one of the most effective methods during the excavation on the water-rich strata in western China. This study on crack initiation and damage stresses of rock at low-temperature conditions has an important guiding role in understanding the failure process of frozen rocks. This paper investigated variations of the crack initiation and crack damage stresses of the sandstone and mudstone samples with decreasing temperature. The results showed that, for the sandstone sample, the crack initiation stress, crack damage stress, peak stress, crack initiation stress ratio (i.e., the ratio of crack initiation stress to peak stress), and crack damage stress ratio (i.e., the ratio of crack damage stress to peak stress) increased linearly with the decreased freezing temperature; for the mudstone sample, the peak stress increased linearly with the decrease of the freezing temperature, but the crack initiation stress, crack damage stress, crack initiation stress ratio, and crack damage stress ratio increased first with the decrease of the temperature then decreased with temperature once it was lower than −10°C. This was because the mudstone sample experienced more severe frost heave damage than sandstone during the freezing process, which caused significant inhomogeneity of the mudstone sample. For the sandstone, the crack initiation stress and crack damage stress increased linearly with the increase of peak stress. Based on the discovered relationships, the peak stress of the sandstone can be predetermined according to the crack initiation stress or crack damage stress of the sandstone. However, for the mudstone, the crack initiation stress and crack damage stress did not show an obvious trend of change with the increase of peak stress. These experimental results were useful for understanding the failure process of frozen rocks in cold regions and artificial freezing engineering.

The harsh marine environment in cold regions challenges the durability of concrete columns in offshore structures. In this study, a steel fiber-reinforced cement-based composite (SFRCC) jacket is proposed to strengthen concrete columns in cold coastal regions. A total of 147 normal weight concrete columns with SFRCC jackets were prepared to examine the compressive behavior after exposure to three typical marine environments: freeze–thaw cycles, wet–dry cycles, and seawater immersion. The investigated parameters include the duration of exposure to marine environments, the specimen shape, and the thickness of the SFRCC jacket. The influence of these parameters on the compressive behavior of normal weight concrete columns with SFRCC jackets was analyzed and discussed. The test results indicate that introducing SFRCC jackets to concrete columns significantly increases compressive strength. In a marine environment, the SFRCC jacket also proved to be an effective strengthening method in terms of residual strength. The compressive strength of normal weight concrete columns with SFRCC jackets after exposure was predicted using a confinement model with a modification factor to incorporate environmental effects. The accuracy of the proposed equation was confirmed by validating predicted values against test results.

The successful construction of cross passages in water-rich sand strata requires the ground reinforcement of soil in passage zones. To address these conditions, artificial ground freezing was introduced, which is an innovative presupport technique that has been extensively applied in tunnel engineering. However, insufficient temperature monitoring data and complex numerical models have hindered accurate predictions of complete freezing curtains in engineering applications. In light of this, this paper proposes a heat–moisture coupling model to predict the dynamic formation of the freezing curtain. This was achieved by combining the heat transfer, Richards’s equation, and the Darcy equation for porous media. As a result, the hydraulic parameters could be obtained through nuclear magnetic resonance. The proposed numerical model was further validated through laboratory testing by applying various seepage flow conditions. Finally, a three-dimensional numerical model was established for the construction of cross passage during artificial freezing. To confirm the feasibility of the model, data from 53 points were continuously collected from the case study for more than 50 days. The proposed model delivers temperature results that are consistent with the field data.

This study proposes a new solar-assisted refrigeration method to protect the permafrost underlying an embankment from degradation. It was initially revealed that the mediocre performance of the current permafrost protection systems was due to a lack of energy needed to make these systems more efficient. In this study, heat-driven adsorption refrigeration technology was considered to satisfy the real-time performance and effectiveness of permafrost protection. A prototype of the solar photothermal adsorption refrigeration pipe was designed and manufactured, and its practical performance was experimentally investigated. The test results indicate that the prototype demonstrates good performance corresponding to the lowest refrigerating temperature of −2.9°C, with an average of −1.5°C in warm seasons. The prototype can also maintain stable output with daily cooling capacity and COP values approaching 81.23 kJ and 0.067, respectively, which can be improved by using a larger apparatus size in practical application. The authors thus conclude that the new structure may be a potential candidate for the thermal maintenance of subgrade engineering.