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Although water table recessions associated with seasonal freezing have been widely reported, the conditions that groundwater could respond to seasonal freezing are poorly known. Based on 30 records of winter-time water table recessions reported in the literature, we find the mean water table recession increases from sand to loam to silt to clay. To obtain a quantitative understanding of the conditions of freezing-induced groundwater migration and the role of soil texture, we construct a one-dimensional SHAW model with a dynamic water table that could respond to winter-time atmospheric conditions. By simulating freezing-induced groundwater migration under a series of pre-freezing water table depths, soil textures and freezing indices, we find the extinction depth of freezing-induced groundwater migration, i.e., the limit water table depth beyond which there is negligible freezing-induced groundwater flow, increases from coarse to fine soils and increases with freezing index. Moreover, we find there is a good linear relationship between the distance from the freezing front to the water table corresponding to the extinction depth of freezing-induced groundwater migration and the distance from the land surface to the water table corresponding to the extinction depth of evaporation-induced groundwater migration for different soils. To demonstrate the importance of defining extinction depth, we also show the overestimation of freezing-induced water gain in the frozen zone by the widely used fixed water table condition when the water table depth is shallower than the extinction depth. This study has implications for future hydrologic and engineering studies in critical zones with a cold climate.

The phenomenon of freezing point depression in frozen soils results in the co-existence of ice and liquid water in soil pores at temperatures below 273.15 K (0°C), and is thought to have two causes: (a) capillary and adsorption effects, where the phase transition relationship is modified due to soil-air-water-ice interactions, and (b) solute effects, where the presence of salts lowers the freezing temperature. The soil freezing characteristic curve (SFC) characterizes the relationship between liquid water content and temperature in frozen soils. Most hydrological models represent the SFC using only capillary and adsorption effects with a relationship known as the Generalized Clapeyron Equation (GCE). In this study, we develop and test a salt exclusion model for characterizing the SFC, comparing this with the GCE-based model and a combined salt-GCE effect model. We test these models against measured SFCs in laboratory and field experiments with diverse soil textures and salinities. We consistently found that the GCE-based models under-predicted freezing-point depression. We were able to match the observations with the salt exclusion model and the combined model, suggesting that salinity is a dominant control on the SFC in real soils that always contain solutes. In modeling applications where the salinity is unknown, the soil bulk solute concentration can be treated as a single fitting parameter. Improved characterization of the SFC may result in improvements in coupled mass-heat transport models for simulating hydrological processes in cold regions, particularly the hydraulic properties of frozen soils and the hydraulic head in frozen soils that drives cryosuction.

Freezing of unsaturated soil is an important process that influences runoff and infiltration in cold-climate regions. We used a simple numerical model to simulate water and heat transport with phase change in unsaturated soil via three different approaches: empirical, semi-empirical and physically based. We compared the performance and parameterization of each approach through testing on three experimental datasets. All approaches reproduced the observed unsaturated freezing process satisfactorily. The empirical cryosuction equation used in this study managed to capture observed cryosuction with a fixed empirical parameter value. The semi-empirical version therefore does not require calibration of a specific frozen soil related parameter. In view of simplicity, small computational demand and accurate performance, all three approaches are suitable for implementation in land-use schemes, catchment scale hydrological models, or multi-dimensional thermo-hydrological models.

As a rule, usually only one face of the building stones of a monument is exposed to climatic variations. Penetration of temperature and humidity stress is unidirectional from the external surface while capillary absorption comes from the bottom part of the accumulation zones such as soil or cornice band. This configuration has to be taken into account in the setting of frost weathering tests in the laboratory. Formation of ice is accompanied by changed volumes and by movements of liquid water due to cryosuction. These phenomena lead to the dilatation of the porous network as assessed by strain gage monitoring. In this study, an experimental setting was developed to simulate the condition of a building stone submitted to frost and water supply by capillary absorption. Strain gages and thermocouples were attached to a limestone sample in order to assess thermal penetration and dilatation changes. Two types of saturation conditions were applied to the sample: water supply only by capillarity and water supply by capillarity after immersion during 48 h. Freeze-thaw cycles of 24-h freezing at − 15 °C and 24-h thawing at + 10 °C were performed. Results showed that deformation perpendicular to the freezing direction was negligible except for the fringe zone where it could reach 6 × 10−4. In contrast, on both sides of the wet fringe, a deformation parallel to the freezing direction occurred, corresponding to an expansion upon freezing and a contraction upon thawing, with an intensity correlated in both cases to saturation. This original test also showed the importance of the capillary fringe in the frost action on building stones that is not taken into account in classical frost weathering tests. And it is to be noted that the strain gages allowed to measure immediate damage before it reached the inside of the stone and before it could be visually perceived.

Soil freeze-thaw (FT) and dry-wet (DW) cycles are brief transitory biophysical changes, but these events have important implications in determining the timing and magnitude of N2O emissions and may represent a significant proportion of annual N2O emissions from agricultural systems. It is often assumed that FT and DW cycles influence the processes of N2O production and emission in a similar manner, however, research has yet to systematically identify the similarities and differences in the mechanisms which lead to potentially higher N2O fluxes during FT compared to DW cycles. Herein, we present the first review to do so; in addition, we identify strategic research areas required for improving the understanding of FT and DW processes leading to N2O emissions. There are key differences between the mechanisms that contribute to N2O fluxes during FT and DW cycles, centered on the duration and spatial extent of anaerobiosis, temperature sensitivity of microbial activity, relative gas diffusivity, and soil water dynamics. These differences might increase the risk of N2O emissions during FT cycles relative to soil DW cycles. Current research gaps include (i) the identification of organic substrates made available due to FT and DW cycles, and their contribution to ensuing N2O fluxes, (ii) an understanding of how cryosuction dynamics potentially influence N2O production and emission, (iii) understanding and predicting the air-entry potential of soil as it relates to N2O fluxes, (iv) identifying the relative significance of dissolved N2O in soil water and its solubility changes during FT and DW phases, and (v) determining microbial community and functional changes across soil spatial and temporal scales. Advances in these areas are recommended for improving process descriptions in biogeochemical models in order to more accurately predict N2O emissions from soils prone to FT and DW cycles.

The Earth's polar regions are experiencing a greater frequency of freeze-thaw events throughout the polar summer, contributing to atmospheric methane and destabilising clay-rich sediments. Clays in soils tightly bind pore water and thus substantially modify freeze-thaw events. While temperatures of phase transitions for confined pore water may be precisely assessed using calorimetric or thermal analyses to −30 or −40 °C, neutron scattering directly probes how pores in clay minerals control ice formation and melting to lower temperatures. We apply elastic neutron scattering to accurately quantify the unfrozen water content of clay gels and unambiguously identify different pore-water environments by their freezing temperatures. Using this approach, we conclude that cryosuction controls water mobility in frozen soils in the absence of soluble salts to much lower temperatures than observed by other techniques. Dyanmics determined from neutron scattering indicates that water in clay gel pores thaws at much lower temperatures than currently considered, and thus pose potential risks for contaminant migration at sub freezing temperatures. The general poor strength of wet clays can significantly impact infrastructure in cold regions undergoing an increased frequency of freeze-thaw events.

Although many frost heave and freezing soil models have been developed in the past decades, saturated conditions are commonly assumed and/or the behavior of pore ice rather than ice lenses are conventionally predicted. This study presents a fully coupled thermal-hydraulic-mechanical (THM) model for variably saturated freezing soil, which examines a number of processes. These include heat conduction and convection, phase change, water (moisture) movement through cryosuction, and the development of independent ice lenses. Instead of directly solving for the pore pressure distributions, the void ratio is considered as a dependent variable related to the degree of water saturation. Both the stress-deformation and ice lens segregation are inextricably linked to the evolution of the void ratio as well. The coupled mechanism and performance of the model is first verified by comparison with laboratory freezing experiment observations obtained from literature and then is further evaluated by a series of parametric analyses. The results show that the calculated profiles of temperature, water content and frost heave are in good agreement with literature experimental data, demonstrating that the proposed THM coupling model appropriately represents the mechanisms of heat-moisture-deformation in variably saturated freezing soil. In addition, the sensitivity analysis illustrates that in the test cases considered, thermally-induced cryosuction due to phase change is the main driving force for water migrating towards the freezing front. Also, ahead of the freezing front, a significant increase in effective stress developed due to the elevated negative pore pressure and expansion of ice lenses causing substantial consolidation and reduction in porosity in the unfrozen zone. As the freezing front penetrated with time, the temperature, moisture, vapour and stress-strain fields interact with each other. The distribution of water vapour was mainly controlled by the temperature gradient and location of the freezing front. Both the initial degree of saturation and hydraulic conductivity affected the distribution of pore pressure and displacements. Higher compression moduli and lower overburden load led to greater frost heave but exerted little influence on the temperature field. Finally, the two-sided freezing scenario for soils underlain by permafrost made the middle ice-poor zone highly compacted with ice lenses accumulating near both freezing boundaries.

Deicing chemicals, when applied to pavement surfaces, occasionally deposited on the ground beyond the road pavement, thus lead to their accumulation in roadside soils and producing secondary salinisation of the ground water. In order to explore moisture and chemical mass transfer in highway subsoils during the winter period, 9 non-saline soil samples of 1 m length were subject to simultaneously freeze–thaw cycles with freezing rate 2 °C/day. To monitor the dependence of mass transfer from the soil density, each further column was packed with increased dry density than the previous one and supplied with 22 g/L of NaCl solution from the base. The results show that soil columns with loose density were consolidated throughout the sample length with the maximum in its lower part. Whilst in the dense soil samples, only the top 10 cm was loosened and attracted a large amount of water to form ice lenses. Chemical mass transfer to the freezing front was observed along the entire length of the samples regardless of density and void ratio. The concentration of de-icing chemicals in the pore water exceeded the supplied solution by 2–2.5 times at the capillary raise zone. In this study, chemical mass transfer is considered in terms of the driving forces and the system equilibrium. The driving force was explained as a cryosuction force, effected to the hygroscopic water in a liquid state with dissolved de-icing chemical ions in it, which migrated towards the freezing front. The continuous secondary salinisation, lasting in the highway subsoils for years, requires an accurate protection as the use of plastic membrane or silicone gel insulation.

This paper introduces a thermo-hydro-mechanical computational model for freezing and thawing in porous media domains, with focus on freezing and thawing in soil. The model is formulated based on the averaging theory and discretized using a mixed discretization scheme, where the standard and extended finite element methods are simultaneously employed. It is capable of capturing the strong coupling between all important phenomena and processes occurring during relatively high freezing-thawing rates in porous media. Solid and fluid compressibility, buoyancy, phase change, thermomechanical behavior, water volume change, pores expansion, cryogenic suction, melting point depression and water migration to the freezing zone are all considered in the model. The cryogenic suction, in particular, is central to the occurrence of many of these phenomena and processes, and thus treated as a primary state variable, and discretized using the partition of unity method to make sure that it can be captured accurately. The paper presents detailed formulation of the governing equations and the numerical discretization. Verification and numerical examples are given to demonstrate the accuracy and computational capability of the model in describing the behavior of a soil mass subjected to boundary conditions resembling those occurring in the vicinity of an energy pile. The numerical examples show that the model is effectively mesh-independent and can simulate all important phenomena using relatively coarse meshes.

Wet frost exposure is a usual environmental condition for cement-based materials (CBM) during winter and the most common way of frost testing in the lab. In this study, the temperature gradient, pressure gradient, and the liquid flow under wet frost exposure are modeled for highly saturated CBM with different amount of entrained air. It is found that the water uptake happens at the melting stage, and for non-air-entrained CBM, the hydraulic pumping effect is dominant and will suck the water from wet surface. While for air-entrained CBM, the cryosuction pressure is the main driving force of the inward flow. The results are compared with experimental data from rapid freeze/thaw testing of various types of concrete in water, showing a satisfactory agreement. Sensitivity analysis also indicates that the hydraulic induced flow depends on the amount of entrained air, while the cryosuction induced flow mainly relies on the permeability and temperature gradient.

Seasonal processes in cold countries significantly affect the engineering characteristics of highway subsoil over time. Cyclical freeze-thaw leads to changes in thermal and moisture conditions. As a result, road bearing capacity can progressively change from the initial design. In this work, a modified laboratory method was developed, with cyclical freeze-thaw of soil samples and simultaneous supply of deionised water and a de-icing agent (sodium chloride) to the base. The benefits of the test procedure included slow freezing, simulating the conditions that can be experienced by highway soils in cold environments, extended soil column heights and a larger number of identical soil samples, which allowed experimental variability to be assessed. The method included the monitoring of moisture and chemical mass transfer in the soils. Samples supplied with deionised water experienced ice segregation in their upper parts, and significant heave. While soils supplied with NaCl solution behaved in a similar fashion during their first freeze-thaw cycle, the second cycle saw a reduction in the rate of migration of the freezing front within the soils and also less ice segregation and less heave due to increased salinity. Salt was preferentially transferred upwards in the soil columns as a result of the thermal gradient, including negative pressure associated with cryosuction, and osmotic pressure. The new method provides a more realistic laboratory approach to assessing potential freeze-thaw impacts, and the effects of de-icing agents on soils beneath roads, and in different settings. JSC Center (International program “Bolashak”).

It is of significance to investigate the deterioration of cement-based systems subjected to freezing temperatures including intrinsic microstructure change and reduction in mechanical resistance. From the microstructure of materials in question, few computer models take the coupled effects of water expulsion, in-pore crystallization and cryosuction into account to assess the realistic internal damage due to frost action. By considering the coupled effects of thermal action, hydraulic pressure and crystallization pressure, this study has established a microstructure-based model to investigate the effects of freezing on micro-internal damage and the macro-mechanical property changes of cement-based systems. Two parts of work are carried out: (1) by coupling a microstructure model HYMOSTRUC3D with a 3D lattice fracture model, the freezing of water in pores and the response of cement paste to the water freezing are captured. Changes in the microstructure of cement paste, represented by the creation of microcracks, are illustrated. (2) Changes in the mechanical properties of cement paste after freezing/thawing are estimated, and the estimated Young's modulus and volume deformation during freezing are compared with those by experiment. In the discussion chapter, from the aspects of thermodynamic considerations, damage sources, crack pattern and deformation, the hydraulic pressure model, ice crystallization pressure model and the newly established model in this study are discussed.

Concentrated colloidal alumina dispersions were frozen in a directional solidification apparatus that provides independent control of the freezing rate and temperature gradient. Two distinct steady-state modes of periodic ice banding were observed in the range of freezing rates examined. For each mode, the wavelength between successive bands of segregated ice decreases with increasing freezing rate. At low freezing rates (0.25-3 μm s(-1)), the ice segregates from the suspension into ice lenses, which are cracklike in appearance, and there is visible structure in the layer of rejected particles in the unfrozen region ahead of the ice lenses. In this regime, we argue that compressive cryosuction forces lead to the irreversible aggregation of the rejected particles into a close-packed cohesive layer. The temperature in the aggregated layer is depressed below the bulk freezing point by more than 2 °C before the ice lenses are encountered; moreover, this undercooled region appears as a light-colored layer. The magnitude of the undercooling and the color change in this region both suggest the presence of pore ice and the formation of a frozen fringe. The possibility of a frozen fringe is supported by a quantitative model of the freezing behavior. At intermediate freezing rates, around 4 μm s(-1), the pattern of ice segregation is disordered, coinciding with the disappearance of the dark- and light-colored layers. Finally, at high freezing rates (5-10 μm s(-1)), there is a new mode of periodic ice banding that is no longer cracklike and is absent of any visible structure in the suspension ahead of the ice bands. We discuss the implications of our experimental findings for theories of ice lensing.

The mechanisms of maintenance of earth hummocks and non-sorted stripes in seasonally frozen ground on the Old Man Range, Otago, New Zealand were investigated. These landforms are hypothesised to be active periglacial landforms maintained by seasonal movement of moisture down an energy gradient. We tested three hypotheses: 1) freezing should occur predominantly in the crests of the stripes and hummocks; 2) differential freezing patterns should be consistent between years; and 3) in the presence of a temperature gradient (i.e. in winter), soil moisture content should be greater in crests than in furrows. An array of 39 thermistors at each of two sites was used to monitor soil temperature gradients during three winters, and replicate soil cores were taken in autumn and winter to determine soil moisture gradients. Freezing occurred mainly in the crests and sides (heavily influenced by aspect), and patterns of freezing showed strong interannual consistency, supporting our first two hypotheses. Soil in crests had a higher moisture content in both freezing and thawed seasons, which was inconclusive relative to the expected water gradient. Copyright © 2008 John Wiley & Sons, Ltd.

There are many competing theories to model concrete exposed to freezing temperatures but few of them provide comprehensive quantitative predictions of the mechanical behavior, while accounting for the multi-scale physics of the confined crystallization of ice. When a part of the liquid in the pores solidifies, a pressure build up is generated, and excess liquid is expelled from the freezing sites towards the remaining part of the porous network. In turn, with increasing cooling a cryo-suction process drives the liquid towards the frozen sites. Unsaturated poroelasticity theory provides new perspectives on the computation of stresses and strains developed in such a complex mechanism. The formulation includes the deformation of all the phases during the freezing process. Special attention is given to the influence of entrained air-voids on the frost resistance of the porous material. The analysis indicates that the air voids act both as expansion reservoirs and efficient cryo-pumps whose respective effects are quantitatively assessed. The theory also allows for the estimation of the critical spacing factor. Numerical simulations are conducted to study the effect of pore size distribution on the critical spacing factor and on the internal pressurization within the porous material as it freezes.

International audience; The durability of Civil Engineering materials relates to multi-physics and multi-scale issues. The improvement of cement-based materials at resisting environmental aggressive conditions depends mainly upon the better understanding of the hydro-mechanical couplings to which they are subjected. The paper addresses the mechanical behaviour of cement-based materials subjected to drying and to the frost action. It is shown how Poromechanics, by combining Thermodynamics, Mechanics of solids and micro-macro considerations, provides a relevant framework in order to understand and to predict the mechanical behaviour of cement-based materials subjected to the various internal actions of water.; La durabilité des matériaux de génie civil relève d'enjeux multi-échelles et multi-physiques. L'amélioration des propriétés des matériaux à base ciment à résister aux agressions environnementales dépend principalement d'une meilleure compréhension des couplages hydro-mécaniques auxquels ils sont soumis. Cet article traite du comportement des matériaux à base ciment soumis au séchage et à l'action du gel. Il est montré comment la poromécanique, démarche combinant la thermodynamique, la mécanique du solide et des considérations micro-macro, fournit un cadre adéquat pour comprendre et prédire le comportement mécanique des matériaux à base cimentaire soumis aux actions internes très diverses de l'eau.

Soils and other porous media influenced by subzero temperatures impose special conditions on the water freezing within them. These conditions have been investigated by many scientists but they have only been described in detail for the last three decades. The coexistence of ice and water in the soil pores is the most fundamental property of frozen soils. Consequently, the study of frozen soils requires consideration of phase change and freezing points. These conditions are very complex and the proper interpretation of field situations by means of the fundamental sciences, requires a careful attention to identifying the terms and concepts used by physicists and chemists with those used by geologists, engineers, soil scientists and others. The author's aim is to present the review of different terms used for describing the process of water migration to the freezing zone. This effect is generally known as a suction or cryosuction. In the following sections, a short literature review and a discussion of the concept of potential of soil water is presented. Understanding of the potential concept as applied to soils is an introduction to understanding the water relations in soil freezing.

We revisit the poromechanics set up by Olivier Coussy for better understanding of the mechanical effect of partial freezing in cohesive porous materials. This approach proves to be able to quantitatively predict swelling even if the in-pore liquid does not expand when solidifying. In this case, dilation results from the so-called cryosuction process that dominates thermal shrinkage under cooling, as shown in our analysis conducted on the historical experiment run by Beaudoin and MacInnis (1974, “The Mechanism of Frost Damage in Hardened Cement Paste,” Cem. Concr. Res., 4, pp. 139–147) on benzene saturated 24-h old cement paste. Both mechanisms are also at work when freezing water saturated early age cement paste with air voids. In this case, the cryosuction process results in shrinkage and should be added to the thermal shrinkage, their respective amplitudes being temperature dependent but, a priori, of the same order of magnitude.

In this research, advanced scanning electron microscopy (SEM) methods were used to characterize the microstructure of cement paste containing entrained air voids. Environmental electron microscopy allowed the imaging of the cement paste without exposing it to high vacuum, significantly eliminating the risk of shrinkage cracks. The fine details of the air-void shell were resolved using field emission microscopy. Lastly, ice crystals inside the air-void were imaged using low-temperature SEM. These microscopy studies showed the presence of a transition layer surrounding the air void, which can have a significant effect on the ice formation inside the air voids. The microscopic analysis confirms that the entrained air voids also cause cryo-suction by driving liquid water from the cement paste during freezing. Both observations are included in a mathematical model that extends the original Powers’ model for freezing of concrete.

International audience; A poro-elastic analysis is undertaken to account for the pressure time history of water-infiltrated pores within a material subjected to freezing. The thermodynamic-mechanical equilibrium of undercooled water and ice crystal, and Poiseuille-like flow through the connection channels, combine to reveal three successive mechanisms: in-pore crystallization, in-pore partial melting and a micro-cryosuction process, driving liquid water from the yet unfrozen pores to the frozen sites. The model turns out to be apt to predict the macroscopic relaxation process observed at the onset of crystallization as reported in the literature for cement-based materials.; Une analyse poroelastisque est entreprise afin de rendre compte de l'évolution de la pression de pore dans un matériau soumis au gel. La prise en compte conjointe de l'équilibre à la fois thermodynamique et mécanique de l'eau surfondue et du cristal de glace, et d'un écoulement visqueux dans les canaux de connection, aboutit à la mise en évidence de trois mécanismes successifs : gel du pore, fonte partielle et cryosuccion, pompant l'eau des pores encore liquides vers les sites gelés. Le modèle s'avère capable de prédire le processus de relaxation macroscopique observé au début de la cristallisation tel que reporté dans la littérature pour les matériaux à base cimentaire.

In many practical situations, adequate thermal design of pavement structures in seasonal frost areas can be done by utilizing a model based on heat conduction alone. In this paper we present a system of computer programs which allow the solution of practically any nonlinear heat conduction problem in soils, provided that a two-dimensional description, plane or axisymmetric, is possible. The finite element method, together with the empirical correlations for thermal properties and boundary conditions, is used in the simulations. Predictions of the thermal regime in different structures are favorably compared with the results of experimental measurements, both for long-term and short-term temperature variations.

High-resolution field data for the period 2000–2014 consisting of active layer and permafrost temperature, active layer soil moisture, and thaw depth progression from the UNISCALM research site in Adventdalen, Svalbard, is combined with a physically based coupled cryotic and hydrogeological model to investigate active layer dynamics. The site is a loess-covered river terrace characterized by dry conditions with little to no summer infiltration and an unsaturated active layer. A range of soil moisture characteristic curves consistent with loess sediments is considered and their effects on ice and moisture redistribution, heat flux, energy storage through latent heat transfer, and active layer thickness is investigated and quantified based on hydro-climatic site conditions. Results show that soil moisture retention characteristics exhibit notable control on ice distribution and circulation within the active layer through cryosuction and are subject to seasonal variability and site-specific surface temperature variations. The retention characteristics also impact unfrozen water and ice content in the permafrost. Although these effects lead to differences in thaw progression rates, the resulting inter-annual variability in active layer thickness is not large. Field data analysis reveals that variations in summer degree days do not notably affect the active layer thaw depths; instead, a cumulative winter degree day index is found to more significantly control inter-annual active layer thickness variation at this site. A tendency of increasing winter temperatures is found to cause a general warming of the subsurface down to 10 m depth (0.05 to 0.26 °C yr−1, observed and modelled) including an increasing active layer thickness (0.8 cm yr−1, observed and 0.3 to 0.8 cm yr−1, modelled) during the 14-year study period.