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Frost heave is major problem for infrastructures build in cold regions. Frost heave occurs due to suction (negative pore water pressure) generated due to the freezing process close to the frost line, i.e., at the frozen fringe. To understand and predict these negative pore water pressures is a key factor to accurately calculate the segregation heave, i.e. heave related to the formation of ice lenses. Segregation heave is the major part of the total heave and also the most challenging to predict. Many attempts have been presented in literature where the generated suction during freezing is related to temperatures, temperature gradients, grain size of the freezing soil etc. Very few laboratory tests have been presented in which the actual suction is measured during the ice lens formation process and compared with theoretical estimations. One reason is that these measurements are challenging. This paper presents results from laboratory measurements of generated suction during freezing. Laboratory tests were conducted on a silty soil sample and suction was measured at the frozen fringe using small pore pressure transducers (PPT’s). The samples were subjected to one-dimensional freezing from top to bottom in an open water system at a constant temperature gradient. Temperatures were measured at various points along the height of the soil sample while suction was measured at middle of the sample. Test results have shown that PPTs do not show pressure change in long-term static pressure test under sub-freezing temperature. For suction measurement at the frozen fringe, pore pressure readings should be measured at various points along the sample height.

Frost heave behavior during soil freezing process is an important issue of concern in cold regions, which is influenced by the hydro-thermal characteristics including the freezing point and water migration. The frost heave is caused by the freeze of water from different sources, i.e. pristine water, migrated water or both; however, it is difficult to identify the contributions of the different water sources to the frost heave, especially for a closed freezing system. Therefore, the calculation method to evaluate the frost heave induced by different water sources still need to be developed. Definitely, freezing experiments under controlled laboratory conditions can help to give a detailed description of the soil freezing process. Therefore, a large-scale one-directional freezing experiment within a closed system was carried out to investigate the hydro-thermal characteristics and frost heave behavior of a saturated silt. The research results showed the effect of the hydro-thermal behavior on the frost heave of the silt within a closed freezing system, and a calculation method was presented to evaluate the frost heaves from pristine water and migrated water, respectively.

Civil engineering buildings are often damaged by frost heave of ground soils in cold regions. The hydro-thermal behavior is a key factor in determining frost heave of soils during freezing process. Moreover, the frost heave is also strongly affected by overburden pressure and external water source. Here, a series of one-directional freezing experiments with a water supply under different applied pressures were carried out to study the effect of hydro-thermal behavior on the frost heave of a saturated silty clay. Four different pressures were applied on the top of each soil sample, respectively, i.e. 50, 150, 300 and 500 kPa. The experimental results indicate that the frost heave of the supplied water is the main component of the total deformation for each soil sample with a water supply. However, the increased applied pressure can restrict water migration, and reduce frost heave during soil freezing process. Furthermore, for the saturated silty clay under different applied pressures, only when the advance rate of the freezing front drops to a critical value, the water intake begins. The start time of the water intake is also delayed with the increased applied pressure. Besides, the shut-off pressure of the saturated silty clay, at which no water flow into or out of the soil sample, is obtained based on the relationship between the critical advance rate of freezing front and the applied pressure.

Snowpack produces a thermal layer that protects soil from freezing and provides a pulse of nutrient-rich water in spring. Climate forecasts for Maine indicate 20–60% reduction in snowfall by 2050. In January 2015, we initiated a snow-removal experiment in Old Town, ME to investigate the impact of snow loss on forest soil conditions. Snow removal significantly lowered winter organic horizon temperatures by 2 °C on average. Soils in snow-removal plots were 25% wetter during the vernal transition because precipitation was not intercepted by snow. These rain-on-soil events caused the formation of concrete frost, delaying soil thaw in snow-removal plots. Our results provide evidence that snowpack loss increases soil frost and can also increase soil moisture, potentially altering biotic function within a coniferous forest type.

Soil frost can have a substantial impact on water flows at the soil surface and—potentially—alter the dynamics of catchment runoff. While these findings are mainly based on studies from alpine and Northern-latitude areas (including permafrost areas), little is known about the significance of soil frost for hydrology in pre-alpine areas, i.e. the region at the transition from central European lowlands to high-alpine areas. Here I synthesize soil temperature data and soil frost observations from ten sites in Switzerland to assess the occurrence of soil frost and to determine its impact on catchment runoff. In addition, a well-established numerical model was used to reconstruct the presence of soil frost in two first-order catchments for single runoff events and winters. The data clearly demonstrates that shallow soil frost has formed regularly in this altitudinal range over the past decade. The presence of a frozen soil surface was found to be highly variable among the sites under study and did not significantly correlate with altitude or forest density. For the first-order catchments, it was not possible to relate important flood peaks or increased runoff coefficients to winter situations with substantial soil frost. Thus, the present analysis suggests that although soil frost is widespread and regularly occurring at this altitudinal range, it has no significant impact on winter runoff in pre-alpine watersheds.

Introducing ultrasonic radar/sensor into current China Meteorological Agency (CMA)’s frozen soil/frost line observation protocol, a method is proposed to automate soil freeze/thaw state monitoring. Two prototypes were built and tested in both lab condition and onsite experiment. Results suggest that the proposed method exhibits application potential and merits further investment in research. The tested prototypes can capture soil freezing process in one-millimeter accuracy and 10 mins data interval. Comparing to CMA’s best practices with one-centimeter accuracy and one data point per day, the proposed method not only automate the monitoring process but also provides better dataset. Challenges emerged during the onsite experiment and improvements were proposed to address the issues.

Embankment deformation is a key consideration in high speed railway construction. Frost heave due to temperature and moisture variation is critical to consider in areas of seasonally frozen ground. This paper examined ground temperatures, frost heave, and moisture content in 2013–2014 at two sites along the embankment of the Harbin-Dalian Passenger Dedicated Line (HDPDL) railway. The railway is in seasonally-frozen ground of Jilin Province, China. The embankment at one site (K977) was built on the undisturbed ground surface while the other was in a cut section (K1004). Displacement measurements over one year indicated that frost heave of 14 mm at K977 and 25 mm at K1004 occurred in ballast during the freezing season. During the annual freeze-thaw period, soil moisture content varied drastically in the upper 0.6 m. The frost depth and freezing index were strongly and positively correlated during the freezing season. Soil moisture content was regarded as the primary control on the amount of frost heave, while frost depth was secondary. Furthermore, water vapor diffusion may have been an important contributor to the formation of near-surface ice. At K1004 site, the maximum recorded deformation was large and exceeded the 15 mm Chinese standard for maximum allowable heave. This suggested that high ground water level increased the amount of frost heave.

1 Standing corn residue has been proven to reduce wind erosion in Northeast China, but how standing corn residue affects soils during winter remained unclear. Our objective was to compare soil frost depth associated with two zero-tillage methods [i.e., chopping corn stalks into small sections then spread them on soil (hereafter referred to as ‘CCR’) and standing corn residue (hereafter referred to as ‘SCR’)]. Frost tubes were used to determine soil frost depth, and soil heat flux plates were used to measure soil heat flux 8-cm beneath the soil surface. Compared with CCR treatment, SCR reduced maximum soil frost depth significantly ( p

Frost damage is a powerful agent of geomorphic change. Cracks can grow when the ice pressure in pores reaches a threshold that depends on matrix properties and crack geometry. Mineral surfaces that are preferentially wetted by liquid water rather than ice are coated by premelted liquid at a pressure that is lower than the ice pressure. Because this pressure difference increases as the temperature cools, when the ice pressure is effectively pinned at the cracking threshold, temperature gradients induce gradients in liquid pressure that draw water towards colder temperatures. Porosity increases and frost damage accumulates in regions where water supplies crack growth. To apply this understanding over the large spatial and temporal scales that are relevant to evolving landscapes, we develop a simple model that tracks porosity changes. Our central assumption is that frost damage is correlated with porosity increases under conditions where frost cracking takes place. Accordingly, we account for the permeability reductions with decreased temperature that accompany ice growth along porous pathways and derive general expressions for the porosity change through time at particular depths, as well as the total porosity increase through all depths beneath a point at the ground surface over the time during which cracking occurs each year. To illustrate the resulting patterns of frost weathering, we consider a general case in which the permeability has a power law dependence on temperature and the annual surface-temperature variation is sinusoidal. We find that the degree of frost damage generally decreases with depth, except at localized depths where damage is elevated because the rock spends longer times near the threshold for cracking, leading to enhanced water supply in comparison with neighboring regions. The magnitude of the net expansion that results from porosity changes at all depths beneath the ground surface is increased for seasonal thermal cycles with larger amplitudes, with a broad maximum centered on a mean annual temperature near the threshold required for crack growth. Warmer mean annual temperatures lead to less damage because of the reduction in time during which it is cold enough for cracking, whereas colder mean annual temperatures are accompanied by reduced water supply due to the temperature dependence of permeability. All of the controlling parameters in our model are tied explicitly to physical properties that can in principle be measured independently, which suggests promise for informing geomorphic interpretations of the role of frost weathering in evolving landforms and determining erosion rates.

The impact of snow cover on seasonal ground frost and freeze-thaw processes is not yet fully understood. The authors therefore examined how snow cover affects seasonal ground frost in a coastal setting in northern Sweden. Air and soil temperatures were recorded in a paired-plot experiment, both with and without snow cover, during the frost season 2012–2013. The frequency, duration, and intensity of the freeze-thaw cycles during the frost season were calculated. The results showed that the freeze-thaw frequency was 57% higher at the soil surface and the intensity 10 °C colder in the spring of 2013, when the ground lacked snow cover. Furthermore, the duration of the seasonal freeze-thaw cycle was 30 days longer on average in cases where there was natural snow accumulation. The correlation between air and ground surface temperatures weakened with increased snow-cover depth. The authors conclude that continued increases in air temperature and decreases in snow in coastal northern Sweden might alter fr...

From August 2014 to September 2016, the Rosetta spacecraft followed comet 67P/Churyumov-Gerasimenko along its orbit. After the comet passed perihelion, Rosetta performed a flyby manoeuvre over the Imhotep-Khepry transition in April 2016. The OSIRIS/Narrow-Angle-Camera (NAC) acquired 112 observations with mainly three broadband filters (centered at 480, 649, and 743 nm) at a resolution of up to 0.53 m/px and for phase angles between 0.095 degrees and 62 degrees. Aims. We have investigated the morphological and spectrophotometrical properties of this area using the OSIRIS/NAC high-resolution observations. Methods. We assembled the observations into coregistered color cubes. Using a 3D shape model, we produced the illumination conditions and georeference for each observation. We mapped the observations of the transition to investigate its geomorphology. Observations were photometrically corrected using the Lommel-Seeliger disk law. Spectrophotometric analyses were performed on the coregistered color cubes. These data were used to estimate the local phase reddening. Results. The Imhotep-Khepry transition hosts numerous and varied types of terrains and features. We observe an association between a feature's nature, its reflectance, and its spectral slopes. Fine material deposits exhibit an average reflectance and spectral slope, while terrains with diamictons, consolidated material, degraded outcrops, or features such as somber boulders present a lower-than-average reflectance and higher-than-average spectral slope. Bright surfaces present here a spectral behavior consistent with terrains enriched in water-ice. We find a phase-reddening slope of 0.064 +/- 0.001%/100 nm/degrees at 2.7 au outbound, similar to the one obtained at 2.3 au inbound during the February 2015 flyby. Conclusions. Identified as the source region of multiple jets and a host of water-ice material, the Imhotep-Khepry transition appeared in April 2016, close to the frost line, to further harbor several potential locations with exposed water-ice material among its numerous different morphological terrain units.© ESO 2019, OSIRIS was built by a consortium of the Max-Planck-Institut fur Sonnensystemforschung, Gottingen, Germany, CISAS-University of Padova, Italy, Laboratoire d'Astrophysique de Marseille, France, Instituto de Astrofisica de Andalucia, CSIC, Granada, Spain, Research and Scientific Support Department of the European Space Agency, Noordwijk, The Netherlands, Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain, Universidad Politechnica de Madrid, Spain, Department of Physics and Astronomy of Uppsala University, Sweden, and Institut fur Datentechnik und Kommunikationsnetze der Technischen Universitat Braunschweig, Germany. The support of the national funding agencies of Germany (DLR), France (CNES), Italy (ASI), Spain (MEC), Sweden (SNSB), and the ESA Technical Directorate is gratefully acknowledged. Rosetta is an ESA mission with contributions from its member states and NASA. Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES, and ASI. The SPICE libraries and PDS resources are developed and maintained by NASA. The authors thank the referee and editors for their questions, remarks, and advices for the improvement of this article.

Frosts and extreme minimum temperature events cause significant damage to grapevines. In the Victorian vine growing regions of Australia, these events may cause complete wipe-out of a season's grape production, and millions of dollars of losses. Frost is an important risk to be managed by viticulturalists, and is likely to change under future climatic conditions with impacts on existing wine-grape growing regions. This case-study applies high spatial resolution analysis of minimum night-time temperatures to explore the impact of current and future frost risks. Multivariate Adaptive Regression Splines (MARS) are used to model high-resolution (30 m grid) minimum temperatures for a topographically diverse region in the Yarra Valley wine region in southeastern Australia. Remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) night-time temperatures, elevation, terrain indices and meteorological station data were used to develop the model of minimum night-time temperatures. The model is formally validated against independent vineyard minimum temperature records (R2 = 0.68) as well as current distribution of viticulture land-use, which was compared with viticulturists' perceptions of a frost-line in the region. Historical temperature records were then adjusted to produce high-resolution maps of frost occurrence under a hot-dry future climate scenario, and a warm-wet scenario, for the years 2030 and 2050. All the future climate scenarios project down-elevation movement of the frost line of between 10 m and 30 m depending on scenarios. This work has implications for viticulturists who might plan to expand growing areas to lower elevations, or might consider changing to different grape varieties. The method developed here could be applied to other regions or used to explore other future climate scenarios. Keywords: Frost, Elevation, Viticulture, Multivariate Adaptive Regression Splines (MARS), Climate change, Moderate Resolution Imaging Spectroradiometer (MODIS)

The NICE model was extended to include the effect of the micro-topography in slope and shading characteristics and the phase changes in soil moisture on snow/frost depths and snowmelt runoff by combining the land-surface, the multi-layer runoff, and the groundwater flow models (NICE-SNOW). The model was applied to the upstream regions of shrinking Kushiro Mire in the invasion of alder, where the spring runoff affects greatly the annual sediment and nutrient transports because the spring flood continues in longer time than that in typhoon seasons. The simulation reproduced excellently the observed values of annual river discharge including snowmelt runoff with the greater time-to-peak of runoff than in snow-free period, in addition to snow depth, frost depth, soil temperature, soil moisture, and groundwater level, by conducting the quantitative assessment of goodness-of-fit and parameter sensitivity analysis. We quantified that the mechanism of spring snowmelt runoff is related to changes in micro-topography, soil structure, soil temperature, soil moisture, and groundwater flow. The model shows that the local effect of snow depth and the frost depth disappears in the snowmelt runoff discharge of catchment in the same way as some previous researches though they are very important as water resources of catchment. After the frozen soil restricts the infiltration in the coldest part of winter, the thawed soil increases the pore size in the early spring. The NICE-SNOW could explain the snowmelt flood continues a longer time than that in the typhoon period because some part of meltwater flows as an intermediate flow in the partially-thawed hillslope soil layer. This is also related to the simulation result that more than half of total soil moisture stays unfrozen at some places even in winter periods, which indicates that there is a high degree of spatial heterogeneity of frozen ground.

The frost table depth is a critical state variable for hydrological modelling in cold regions as frozen ground controls runoff generation, subsurface water storage and the permafrost regime. Calculation of the frost table depth is typically performed using a modified version of the Stefan equation, which is driven with the ground surface temperature. Ground surface temperatures have usually been estimated as linear functions of air temperature, referred to as ‘n-factors’ in permafrost studies. However, these linear functions perform poorly early in the thaw season and vary widely with slope, aspect and vegetation cover, requiring site-specific calibration. In order to improve estimation of the ground surface temperature and avoid site-specific calibration, an empirical radiative–conductive–convective (RCC) approach is proposed that uses air temperature, net radiation and antecedent frost table position as driving variables. The RCC algorithm was developed from forested and open sites on the eastern slope of the Coastal Mountains in southern Yukon, Canada, and tested at a high-altitude site in the Canadian Rockies, and a peatland in the southern Northwest Territories. The RCC approach performed well in a variety of land types without any local calibration and particularly improved estimation of ground temperature compared with linear functions during the first month of the thaw season, with mean absolute errors

Frost heave, which is the volumetric expansion of frozen soil, has great ecological significance, since it creates water storage spaces in soils at the beginning of the growing season in cold temperate forests. To understand the characteristics of frost heave in seasonally frozen soil and the factors that impact its extent, we investigated the frost heave rates of forest soil from different depths and with different soil moisture contents, using both lab-based simulation and in situ measurementin a broadleaved Korean pine forest in the Changbai Mountains (northeastern China). We found that frost heave was mainly affected by soil moisture content, soil type, and gravitational pressure. Frost heave rate increased linearly with soil moisture content, andfor each 100% increase in soil moisture content, the frost heave rate increased by 41.6% (loam, upper layer), 17.2% (albic soil, middle layer), and 4.6% (loess, lower layer). Under the same soil moisture content,the frost heave rate of loam was highest, whereas that of loess was lowest, and the frost heave of the uppermost 15 cm, which is the biologicallyenrichedlayer, accounted for ~55% of the frost heave. As a result, we determined the empirical relationship between frost heave and freezing depth, which is important for interpreting the effects of frost heave on increases in the storage space of forest soils and for calculating changes in soil porosity.

The response of seasonal soil freeze depth to climate change has repercussions for the surface energy and water balance, ecosystems, the carbon cycle, and soil nutrient exchange. Despite its importance, the response of soil freeze depth to climate change is largely unknown. This study employs the Stefan solution and observations from 845 meteorological stations to investigate the response of variations in soil freeze depth to climate change across China. Observations include daily air temperatures, daily soil temperatures at various depths, mean monthly gridded air temperatures, and the normalized difference vegetation index. Results show that soil freeze depth decreased significantly at a rate of −0.18 ± 0.03 cm yr−1, resulting in a net decrease of 8.05 ± 1.5 cm over 1967–2012 across China. On the regional scale, soil freeze depth decreases varied between 0.0 and 0.4 cm yr−1 in most parts of China during 1950–2009. By investigating potential climatic and environmental driving factors of soil freeze depth variability, we find that mean annual air temperature and ground surface temperature, air thawing index, ground surface thawing index, and vegetation growth are all negatively associated with soil freeze depth. Changes in snow depth are not correlated with soil freeze depth. Air and ground surface freezing indices are positively correlated with soil freeze depth. Comparing these potential driving factors of soil freeze depth, we find that freezing index and vegetation growth are more strongly correlated with soil freeze depth, while snow depth is not significant. We conclude that air temperature increases are responsible for the decrease in seasonal freeze depth. These results are important for understanding the soil freeze–thaw dynamics and the impacts of soil freeze depth on ecosystem and hydrological process.

Monitoring near-surface soil freeze/thaw patterns is becoming essential under the context of global changes as it is more sensitive to climatic fluctuation compared with subsurface thermal characteristics and its evolution could be an early warning of changes in near-surface permafrost. It requires continuous long term and stable data record for understanding hydrological, ecological and biogeochemical responses of permafrost to global climate change. AMSR2 (Advanced Microwave Scanning Radiometer 2) is designed as a successor of AMSR-E (Advanced Microwave Scanning Radiometer – Earth Observing System) to ensure continuity of such observation. In this study, a linear regression is used to inter-calibrate the AMSR-E and AMSR2 brightness temperatures. Then discriminant function algorithm is adopted to produce a long term freeze/thaw data record. It is compared with in situ air temperature measurements from both the temporal and spatial aspects. The results show that the accuracy is consistent between AMSR-E and AMSR2 with a value above 85 %, according to the result of spatial distribution accuracy. Analysis is conducted with this data record to explore the spatial distribution of frost days, its changing trend and the frost probability of each pixel on a specific date. The mean annual frost days of high northern latitude (HNL, > 45° N) zone is 214.2 ± 69.5 days and the trend of frost days indicates that the frost period is decreasing at a rate of −0.0065 day/month in 27 % of the domain which is defined by significance level of the F-test, and most of which are concentrated in the high latitude area specifically over the Northeast of Canada, Central and Eastern Russia and most part of Eastern Europe. The significant changes in frost days mostly occur in regions of discontinuous permafrost and transient permafrost. The spatial distribution of the frost days and its trend variations are found to be consistent with the minimum temperature anomalies trend. It indicates that the global warming is not constant at different regions over the globe. Further analysis over the Qinghai-Tibetan Plateau where discontinuous permafrost, island permafrost, seasonally frozen ground exist demonstrated that the frost period is shortening slightly over the past decade, and the last frost date is advanced over more than half of the region. It is considered to be a remarkable indication for permafrost degradation in this area.

An innovative approach to mitigate frost heave problems in flexible pavements is to inject a two-part expanding polymer at the bottom of the subbase. As the polymer expands, it creates an insulation layer that minimizes heat loss from the profile and prevents the frost front from entering the subgrade. The technique has been used in a section of Wyoming highway WY-70 6.4 km west of Encampment, WY. A two-year study measured road surface deviations and temperatures in the soil profile. The frost heave over a 30-m long section was reduced from greater than 75 mm to less than 17 mm. The maximum frost penetration depth was determined in five holes over two seasons using the measured temperature data in the road/soil profile including boreholes with 0, 25, and 75 mm of expanded polymer. These data were compared to depths predicted by the Modified Berggren Equation. The standard deviation for the ten estimates was 52 mm over a range of freezing depths from 500 mm to 1100 mm. The maximum error of prediction was 82 mm, while five of the ten errors were less than 20 mm. It was determined that the polymer behaved like volumetric latent heat. The technique appears to successfully predict the frost depths well enough to use as a predictor in design. However, these results are based solely on an analysis using Uretek 486 STAR #3 structural polymer at this site and time period.

O objetivo deste trabalho é avaliar a influência do tipo de poliolefina e da razão de sopro (RS) nas propriedades físicas e térmicas de filmes produzidos em processo de extrusão tubular. No processamento foram utilizados um polietileno de baixa densidade (PEBD) e um polietileno de alta densidade (PEAD) transformados numa linha de extrusão de filme tubular com três RS de 1,5:1; 2,5:1 e 3,5:1. Os resultados das caracterizações físicas dos filmes mostraram maior variação de espessura no perímetro dos filmes tubulares de PEAD, quando comparados aos de PEBD. O aumento da RS causou uma diminuição de amplitude desta variação nos filmes tubulares de PEBD e diferenças nas propriedades ópticas. O coeficiente de atrito (COF) dos filmes foi menor para o PEAD e não teve variação significativa com o aumento da RS utilizada. Em relação às propriedades mecânicas, os filmes de PEAD apresentaram maior resistência à tração e menores valores de deformação no ponto de escoamento em ambas as direções. As RS maiores apresentaram similaridade nas tensões e nas deformações entre as direções da máquina (DM) e transversal (DT). A RS ideal, constatada para os filmes processados com PEBD, é 2,5:1 e com PEAD, é 3,5:1. Os filmes de PEAD apresentaram opacidade maior e menor brilho, quando comparados aos filmes de PEBD. Os resultados comprovaram valores conhecidos na literatura, entretanto introduziu-se uma inovação neste estudo: a utilização da técnica termográfica digital portátil, que permite visualizar, de maneira instantânea (on-line), as variações de temperatura no perímetro do balão, na zona de névoa (região de cristalização ou solidificação do filme). The purpose of this study is to evaluate the influence of the polyolefin type and the blow-up ratio (BUR) on the thermal physical properties of films produced in a blown film extrusion process. It was used low density polyethylene (LDPE) and high density polyethylene (HDPE) processed in a blown film extrusion line at three BUR of: 1.5:1; 2.5:1 and 3.5:1. The results of physical characterization on these films demonstrated that the increase in the BUR shows a higher thickness variation in the perimeter of tubular films and, therefore, optical properties variation. The coefficient of friction (COF) of the films was smaller for HDPE and did not have significant variation with the increase in the BUR applied. Regarding mechanical properties, HDPE films showed higher tensile strength and lower strain values in the yield point, in both directions. The largest BUR showed higher similarity of the tensions and strains between the machine direction (MD) and transverse direction (TD). The ideal BUR observed for films processed with LDPE is 2.5:1, for HDPE this number is higher and close to 3.5:1. The HDPE films showed more opacities and less brightness when compared to LDPE films. The results prove well known values in the literature, however, there was an innovation introduced in this study which is the use of the portable digital thermo graphic technique that allows the instantaneous visualization (on-line) of the temperature variation in the bubble perimeter in the frost line (crystallization or solidification area of the film).

Frost is a decisive factor influencing pavement performance in cold countries. In the EU, millions of euros are spent annually on winter maintenance. About one-third of the maintenance budget is allocated to rehabilitation due to the negative impact of frost. The negative effect of frost is restricted by using non-frost-susceptible materials within the frost zone and regulating water accumulation. However, experience shows that the thickness of constructed pavement structure is often inadequate and that frost penetrates into the subgrade of frost-susceptible materials. The aim of this paper is to introduce the thickness calculation approach of the frost resistant pavement structure using road weather station (RWS) data. The subgrade susceptibility to frost and the number of equivalent single axle loads (ESALs) are considered as factors too. The calculated thickness of the frost resistant pavement structure is corrected according to the specific local conditions. After performing a statistical analysis of 2012–2014 data pertaining to 26 RWSs, Lithuania was divided into four regions according to the maximum frost depths, where the maximum values depending on RWS location varied from 110.4 cm to 179.1 cm.