Amount Of Frost Heave Research Articles

Changes in the standard freezing depth of seasonally frozen ground in China over the last 50 years

ABSTRACT In recent years, under the influence of global warming, the freezing depth of seasonally frozen ground (SFG) has decreased at an accelerating rate. This has affected engineering and construction insofar as accurate determinations are needed of SFG areas and the amount of frost heaving. In this study, a method of deriving the E-factor using the improved Stefan formula was used to study changes in the standard freezing depth (SFD) of SFG in China. The method was used to reveal the trends and patterns of changes in the SFD of SFG over the past fifty years. The study relied on ERA5L and reanalysis data and empirical formulas for standard sites in China’s SFG regions. Raster data of the interdecadal SFD in SFG areas of China from 1971 to 2020 were generated to analyze changes in the SFD. Our results show that in the past fifty years, the SFD in China’s SFG areas has shown a downward trend, with the SFD changing at an average rate of −6.749 cm/10a years. The average SFD in the 1970s, 1980s, 1990s, 2000s, and 2010s was 111.31, 107.13, 95.69, 89.84, and 86.21 cm, respectively. From the overall performance of the SFD in different decadal periods, the SFD in central and northeast China changed sharply within the range of 35° N to 50° N in SFG regions. The boundary lines of low-value SFDs expanded sharply to the north as the latitude increased, and the boundary lines of high-value SFDs contracted sharply.

Influence of frost heave with confining pressure under seepage on compressive strength of frozen silt in artificial ground freezing

Artificial ground freezing (AGF) is used for constructing subway cross passages in coastal areas. The continuous construction of complex projects (cross-sea or cross-river tunnels) has resulted in freezing environments with high groundwater seepage velocities. Seepage cannot provide an open system in soil freezing for moisture migration, resulting in large amount of frost heave owing to segregated ice compared to close freezing system. The influence of frost heave under seepage on the compressive strength of frozen silt during artificial ground freezing must be studied to ensure AGF construction safety. Thus, a unidirectional freezing device that can control seepage and confining pressure conditions during freezing was designed to prepare frozen silt samples under different seepage velocities with confining pressures and to measure the relevant segregation frost heave. Subsequently, uniaxial compression tests were performed. The compressive strength of frozen silt under the influence of frost heave and seepage conditions was analyzed. The frost heave rate, uniaxial compressive strength, and elastic modulus of frozen silt in an open freezing system were measured. The seepage velocity during freezing increased the frost heave rate of the silt; the uniaxial compressive strength and elastic modulus of the frozen silt increased subsequently. The effective confining pressure suppressed frost heave of silt and reduced the uniaxial compressive strength and elastic modulus of the frozen silt. The test results were analyzed considering the segregation frost heave formation mechanism, and a theoretical improvement model of the uniaxial compressive strength and elastic modulus of frozen silt related to the content of segregated ice was proposed. This research is significant for ensuring the AGF construction safety in cross-river or ocean tunnel engineering under seepage conditions.

Determination of parameters of anti-heave structures of the subgrade taking into account the freezing system

Background: in the Northern Hemisphere, during the construction and operation of railways, one of the pressing problems is frost heaving. One of the key factors influencing the amount of frost heaving is the occurrence of groundwater relative to the freezing front of the subgrade soils, which is not fully taken into account by existing approaches to determining the parameters of anti-heaving structures. This factor is usually characterized by freezing regimes, there are two of them - open and closed freezing systems. An open system is characterized by the proximity of groundwater to the freezing front, at which there is a constant influx of water (migration) to the zone of phase transitions, which makes the process of frost heaving unpredictable, and the determination of the frost heave ratio incorrect. A closed freezing system assumes the absence or deep location of groundwater (the difference in the level of the freezing front and groundwater exceeds the height of the capillary rise of water).
 Aim: development of a method for calculating the parameters of anti-heaving. structures depending on the freezing regime of railway subgrades.
 Materials and Methods: comparative analysis of methods for calculating the parameters of anti-heaving structures, experimental studies of the process of frost heaving in an open system of freezing of clay soils.
 Results: based on experimental studies of freezing regimes, a differentiated approach to assessing the characteristics of frost heaving is proposed, taking into account the peculiarities of the frost heaving process.
 Conclusion: the proposed method with a differentiated approach compares favorably with existing ones, allowing to reduce the consumption of building materials when designing anti-heaving measures.

Numerical simulation of frost heave of saturated soil considering thermo‐hydro‐mechanical coupling

AbstractFrost heave can lead to both the ground uplifting and frost heave pressure under different circumstances, and cause many engineering problems. To describe the characteristics of frost heave under various thermo‐hydro‐mechanical (THM) coupling conditions and calculate both the frost heave amount and the frost heave pressure, the coupled THM process, as well as the phase change of the pore water, should be considered for freezing soil. In this paper, thermodynamic equilibrium conditions in saturated freezing soil were derived to account for the mechanical effect on the cryogenic suction and unfrozen saturation of pore water during phase transition. Then the governing equations were developed considering the water flow, heat transfer, stress equilibrium, phase change, ice segregation, and their complex interactions. Based on that, a numerical model considering fully THM coupling is presented within the framework of finite element provided by COMSOL. Both frost heave amount tests and frost heave pressure tests were simulated to verify the proposed model. Then the model was applied to subgrades with different types of soil and different boundary conditions, to reveal the characteristics of frost heave amount and frost heave pressure under different conditions, and at the same time to demonstrate the model's applicative prospect.

Remediation of large-scale model experiment for heavy metal contaminated clayey soil: An optimized mass transfer process strategy of freeze-thaw and washing

To reduce the limitations of the chemical washing method due to soil texture, the freezing technique has been used to enhance the mass transfer efficiency between the eluent and heavy metal contaminants. With the optimized water supplement and cooling conditions, a large-scale model experiment was conducted. Results show that the optimized method is prone to enhancing the eluent intake of clayey soil, leading to an increase in the amount of soil frost heave, which has a feedback effect by breaking the soil structure and enhancing the eluent intake. The synergistic effect of the two is responsible for the improvement of washing efficiency. In addition, after four freeze-thaw and washing cycles, the total removal rates of the metallic elements Pb and Cd reach 58.73% and 69.04%, respectively, satisfying the soil environmental quality standard. The soil bioavailability is effectively reduced by alternating the eluent with ethylenediaminetetraacetic acid (EDTA) and water, thereby reducing the bioavailability of Pb and Cd by 66.01% and 74.18%, respectively. This remediation strategy for heavy metals in clayey soils utilizes alternate freezing and thawing (natural cold energy) in seasonally frozen regions, which is beneficial for constructing an ecological civilization and protecting the environment.

Experimental Study on the Effect of Fines Content on the Frost Swelling Characteristics of Coarse-Grained Soil in Canal Base Under Open System

Abstract Engineering usually considers coarse-grained soils as non-frost swelling soils, but serious frost swelling still occurs in coarse-grained canal bases, which is directly related to the recharge conditions and the fine particle content in the soil. Little attention is currently paid to the effect of different fine particle contents on coarse-grained soil frost swelling, especially after the fine particle admixture content exceeds 16%. This paper considers the characteristics of coarse-grained soils in water conservancy projects with fines content between 0% and 50%. The coarse-grained soils with 5%, 15%, 25%, 35%, and 45% fines content were designed for freezing and swelling tests. The evolution of temperature and moisture fields and the amount of freezing and swelling of coarse-grained soils during the freezing process were studied by using servo-type freezing and swelling and thawing tester. The experimental results show that the cooling process of soil samples can be divided into a rapid cooling stage, a slow cooling stage, and a freezing stabilization stage. The cooling rate and the frost heave amount with increasing fines content showed a trend of first increasing and then decreasing.

Experimental study on the influence of initial water saturation on segregation frost-heaving behavior in silty clay columns

The impact of initial water saturation on segregation frost heaving behavior was investigated by conducting 1-dimensional (1-D) soil column freezing tests with a water supply. The test results demonstrated that: (1) A frozen fringe with segregation cracks was observed in all tested soil columns. Water migrated towards the frozen fringe and transformed into segregated ice. After freezing, the total water content in the segregation zone could reach double or triple its initial value. (2) The segregated ice destroyed the soil's initial fabric and enhanced the soil void. The ice saturation in the segregation cracks reached just 0.5. (3) The total frost heave amount, frost heave ratio, segregated ice content, and the segregation crack width were all linearly related to the initial water saturation. (4) Frost heave was significant in silty clay with an initial water saturation greater than 0.53. The results reveal initial water saturation to be the primary factor controlling frost heave in silty clay and should thus be given appropriate attention in the design of frozen soil engineering.

Ground Surface Displacement After a Forest Fire Near Mayya, Eastern Siberia, Using InSAR: Observation and Implication for Geophysical Modeling

AbstractForest fires significantly impact permafrost degradation in the subarctic regions. However, interannual and seasonal variations in surface deformation due to permafrost thawing in burned areas were poorly understood. Measuring the ground surface displacement in fire scars helps us understand the freeze‐thaw dynamics of near‐surface ground and predict the future state, particularly in ice‐rich permafrost regions. This study used the L‐ and C‐band interferometric synthetic aperture radar technique to reveal interannual subsidence and seasonal thaw settlement/frost heave in a fire scar near Mayya, Sakha Republic in Eastern Siberia burned in 2013. We found that the cumulative subsidence was up to 7 cm between 2014 and 2020, most of which had occurred by 2016. The magnitude of seasonal thaw settlement and frost heave varied each year from 2017 to 2020 after the fire, but the interannual change in frost heave corresponded to the temporal variation in precipitation during the thawing season from 2017 to 2020. This suggests that the precipitation amount during the thawing season is related to the magnitude of segregation‐ice formation in the sediments, which determines the frost heave amount. The observed seasonal displacements could not be quantitatively explained by models inferred from the Stefan's equation and volume changes associated with ice‐water phase change. This implies that other models associated with segregated ice (ice lens) formation/thaw are required to explain the observed seasonal displacement.

Experimental Study on the Effect of Initial Water Content and Temperature Gradient on Soil Column Segregation Frost Heave

A series of freezing experiments were carried out on the Qinghai silty clay using a one-dimensional soil column particle image velocimetry (PIV) system. The effects of the initial water content and temperature gradient on the frost heave of the soil column were analysed. The experimental results show that the total volumetric water content after the Qinghai silty clay freezing is much greater than the initial water content before freezing, and the total volumetric water content at the segregated layer reaches the maximum value. The average unfrozen water content firstly increases sharply with time and then decreases slowly. The obvious horizontal layered segregation cracks filled with unsaturated needle-columnar ice lenses have occurred above the soil column frozen fringe. The thickness of segregated ice is about 43% of the total frost heave. There is a small frost heave in the frozen fringe and a small compression deformation amount in the unfrozen zone. Under the same temperature gradient conditions, the soil column with the low initial water content has a smaller frozen depth, larger total volumetric water content, more water intake, smaller segregated ice thickness, and less total frost heave amount than that of the soil column with the high initial water content. Under the same initial water content conditions, the soil column with a large temperature gradient has a greater frozen depth, consistent total volumetric water content, larger segregated ice thickness, and greater total frost heave amount than that of the soil column with a small temperature gradient.

Experimental Study on Frost Heave Behavior of Steel Fiber Improved Soil

The incorporation of steel fibers into the natural soil is generally considered to be a novel and effective way to reduce the amount of frost heave induced by an artificial freezing process in underground engineering. In order to analyze the frost heave behavior of the steel fiber improved soil, a one-dimensional frost heave test under the open recharge system was conducted in this paper, focusing on the influence of steel fiber content, size, and soil properties. The results show that small amounts of steel fibers in the soil will not significantly affect the freezing process and temperature distribution, while the water-conducting properties of the steel fibers and the effect of limiting the ice lens growth can reduce the frost heave rate of the samples incorporated with 0.5% steel fibers by 26.93%. At the same time, the reduction effect of the frost heave rate increases linearly with the increase of steel fiber content and length but weakens with the increase of steel fiber diameter. In terms of soil property influence, the frost heave rate of the clay samples was reduced by 14.31% compared to the silt samples, while the water migration was reduced by 11.99%. In addition, the cementation of the steel fibers with the soil will also inhibit the growth of the ice lens and reduce the external water migration, thus significantly lowering the frost heave rate. The results can provide a reference for the research of the frost deformation of similar modified soils.

Thermal-hydro-mechanical coupled analysis of unsaturated frost susceptible soils

Damage caused by frost heave leads to costly maintenance in cold regions, like Hokkaido, Japan. Therefore, the study of the frost mechanism with experimental and numerical methods has been of great interest. Numerous models have been developed to describe the freezing process of saturated soil, which differs from the partially saturated conditions in the field. In fact, most subsurface soils are unsaturated. The freezing process of partially saturated soils is more complex than saturated soils, as the governing equations show strongly nonlinear characteristics. This study proposes a thermo-hydro-mechanical coupled model considering the heat transfer, water infiltration, and deformation of partially saturated soil to reproduce the freezing process of partially saturated frost susceptible soils distributed in Hokkaido. This model better considers the water-ice phase change and soil freezing characteristic curve (SFCC) during freezing under field conditions. The results from the multiphysics simulations agree well with the frost heave and water migration data from frost heave tests of Touryo soil and Fujinomori soil. In addition, this study discussed the influence of the various factors on frost heave amount, including temperature gradients, overburden pressures, water supply conditions, cooling rates, and initial saturation. The simulation results indicate that the frost heave ratio is proportional to the initial degree of saturation and is inversely proportional to the cooling rate and overburden pressure.Moreover, simulation under the open system generates much more frost heave than under the closed system. Finally, the main features of the proposed model are revealed by simulating a closed-system frost heave test. The simulation results indicate that the proposed model adequately captures the coupling characteristics of water and ice redistribution, temperature development, hydraulic conductivity, and suction in the freezing process. Together with the decreased hydraulic conductivity, the increased suction controls the water flow in the freezing zone. The inflow water driven by cryogenic suction gradient feeds the ice formation, leads to a rapid increase in total water content, expanding the voids that exceed the initial porosity and contributing to the frost heave.

Experimental and analytical investigation on frost heave characteristics of coarse-grained soils under closed and open systems

Coarse-grained soil is widely used in the seasonal frozen soil region as subgrade filler. However, substantial frost heave has been observed in coarse filler in high-speed railway embankments. To investigate the frost heave characteristics of the coarse-grained soil in a deep seasonal frozen soil zone, indoor tests were carried out under water supply and no water supply conditions. The effect of water, fineness, and temperature on frost heave behavior is studied experimentally. The relationship between the freezing rate and frost heave of coarse-grained soils was analyzed. The results show that the freezing process of the filler can be divided into the rapid cooling stage, phase transition stage, slow freezing stage, and freezing stability stage. In the closed system, the increase of the fine-grained soil does not affect the cooling process, while the moisture content significantly affects the whole process. In the opened system, both the fine-grained soil content and the ambient temperature affect the cooling process. When the ambient temperature decreased from −5°C to −15°C, the duration of the phase transition stage decreased by almost 17 h, whereas when the fine-grained soil content increased from 2.7 to 16%, the duration of the phase transition stage increased by only 5 h. In both opened and closed systems, the development of the frost heave is closely related to the cooling process. Approximately 95% of frost heave occurs during the phase transition stage and slow freezing stage. Frost heave develops most rapidly in the phase transition stage, with approximately 85% of the frost heave amount occurring in this stage.

Thermomechanical Coupling Analysis of the Lining Structure of the Tunnel Entrance in Cold Regions Based on Peridynamics

To explore the effect of frost heaving of the tunnel entrance in cold regions, this paper carries out a thermomechanical coupling analysis based on peridynamics (PD), combines PD with finite-element method (FEM) into a numerical model, and verifies the feasibility of the proposed model. On this basis, we selected frost heave amount as the quantitative index, discussed the evolution law of the energy field in the lining structure of the tunnel entrance in cold regions, and analyzed the stress of the lining structure, as well as the expansion and distribution laws of lining cracks, under different frost heave amounts. The results show that: The difference of frost heave amount indirectly brings changes to the system’s energy field. With the growth of frost heave amount, the thermal potential and strain would increase. During the changes, the thermal potential and strain energy of the system are both positively correlated with frost heave amount. The degradability of tunnel lining increases with the frost heave amount of the lining. A high density of cracks can be observed at the foot and waist of the arch, most of which are tensile cracks. With frost heave amount as the main temperature reference, this research explores the degradation state of the tunnel entrance in cold regions, which greatly facilitates the maintenance, repair, and safe operation of tunnels.

Water-Rich Soft Soil Freezing Method Combined With Steel Sleeve Receiving-Shield Technology Field Test Research

The initiation and reception of shields are major risk events for shield construction in water-rich and weak strata. Although the freezing method and the steel sleeve method receiving-shield tunneling technologies both have engineering applications, the environmental safety control effect cannot meet the construction requirements of water-rich soft soil. Considering the shield construction of a typical soft soil layer in Suzhou, China, as a research target, the applicability and safety of the freezing method combined with steel sleeve receiving-shield technology in water-rich soft soil were evaluated based on a field test system. The test results show that, during soil freezing, the temperature change trend of each measuring point in the temperature measuring hole is roughly the same. The freezing process can be divided into five typical stages. The closer the active freezing period of the water-rich soft soil is to the inside of the frozen-soil curtain, the faster the development rate of the frozen wall. The soil cooling gradient increased with an increase in the radial depth. After freezing the curtain circle, the soil frost heave significantly accelerated until the frost heave amount peaked. During the construction process, special attention should be paid to the change in the value of the soil settlement during each stage change to prevent sudden changes in soil displacement. The freezing method, combined with steel sleeve receiving-shield technology, can effectively reduce the environmental disturbance caused by shield construction in water-rich soft soil.

A Freezing-Thawing Damage Characterization Method for Highway Subgrade in Seasonally Frozen Regions Based on Thermal-Hydraulic-Mechanical Coupling Model

Seasonally frozen soil where uneven freeze–thaw damage is a major cause of highway deterioration has attracted increased attention in China with the rapid development of infrastructure projects. Based on Darcy’s law of unsaturated soil seepage and heat conduction, the thermal–hydraulic–mechanical (THM) coupling model is established considering a variety of effects (i.e., ice–water phase transition, convective heat transfer, and ice blocking effect), and then the numerical solution of thermal–hydraulic fields of subgrade can be obtained. Then, a new concept, namely degree of freeze–thaw damage, is proposed by using the standard deviation of the ice content of subgrade during the annual freeze–thaw cycle. To analyze the freeze–thaw characteristics of highway subgrade, the model is applied in the monitored section of the Golmud to Nagqu portion of China National Highway G109. The results show that: (1) The hydrothermal field of subgrade has an obvious sunny–shady slopes effect, and its transverse distribution is not symmetrical; (2) the freeze–thaw damage area of subgrade obviously decreased under the insulation board measure; (3) under the combined anti-frost measures, the maximum frost heave amount of subgrade is significantly reduced. This study will provide references for the design of highway subgrades in seasonally frozen soil areas.

Frost susceptibility of Nordic metal mine tailings

The mining industry produces significant amounts of waste materials, with the greatest volumes generated during enrichment. These waste materials or by-products, tailings, may be used as alternative civil engineering materials, reducing the need for natural resources. In cold climates, the frost behaviour of materials is one critical functional requirement in civil engineering applications. The frost behaviour of tailings classified as sand, silty sand, or sandy clayey silt (EN ISO), from four metal mines located in northern Finland and Sweden, was evaluated in this study using basic laboratory characterisation and one-dimensional freezing tests. The laboratory results were compared with existing guidelines on estimating the frost susceptibility of natural soils. Based on grain size distribution, the tailings samples were characterised as non-susceptible or frost-susceptible. Capillary rise values indicated that the frost susceptibility of the samples ranged from negligible to strong. In the one-dimensional frost heave test, measured frost heave after 96 h was 0.1–23.1 mm and calculated segregation potential (SP) was 0–9.7 mm2/Kh. Based on the frost heave test, the frost susceptibility of the samples ranged from low to strong. The results indicated that the finest samples classified as sandy clayey silt (L1−L3) generated the majority measured amount of frost heave and were classified as frost-susceptible material. The coarser tailings samples (K1-K3 and AK1) classified as sand or silty sand were classified non-susceptible, and measured frost heave amounts were low <1.0 mm (after 96 h). Thus, the tailings samples behaved like natural soils, indicating that classification methods developed for natural soils are valid for evaluation of the frost susceptibility of mine tailings. However, the influence of added reagents should be considered, and standardised frost behaviour methods should be developed.

An Example of Damage to Slope Stabilization Work Caused by The Frost Heaving of Mudstone and Its Countermeasure

In this study,field surveys were carried out at the damaged area of slope stabilization works,where the main cause was presumed to be the frost heaving of the rock mass.Field measurements of the freezing depth and the amount of frost heave were also conducted.In addition, the effectiveness of the slope stabilization work with the frost heave measures was verified based on the investigation results.The findings are summarized as follows. (1) From the results of the field survey and the field measurements,it was found that even if frost heaving occurred in the extreme surface layer, the rock mass would be degraded and the slope stabilization work would be affected.(2)From the results of the frost heaving tests, it is clear that the frost susceptibility of the damaged rock slope is extremely high, and there was wide agreement between the results of the frost heaving tests and the results of determining the frost susceptibility of the damaged rock slope using a simple strength test method. Therefore, the validity of the simple method proposed by Nakamura et al. for determining the frost susceptibility of rocks by using the strength test was also verified. (3)It was confirmed that both the gabion and the continuous fiber reinforced soil work were effective in preventing the freezing front from advancing into the rock mass.The method of covering the rock slope with non-frost susceptible material to prevent the penetration of the freezing front was found to be effective as a countermeasure against frost heaving.

Development of a Frost-Heave Testing Apparatus with a Triple Cell

In this study, the first frost-heave testing apparatus with a triple cell was developed that can measure the amount of frost-heave and heaving pressure, as well as achieve high-accuracy temperature control. The performance of the apparatus was validated by a series of frost-heave tests, which were conducted in a closed system with saturated sandy soil and an initial boundary temperature of 3 °C. The effect of having multiple cells (triple cell, double cell, and single cell), different freezing directions (top to bottom, both sides, and bottom to top), and multiple temperature gradients (0.09, 0.11, and 0.13 °C/mm), was examined to investigate the frost-heave properties of sandy soil. The reliability of the testing machine was validated by comparing the measured (experimental) and estimated (theoretical) amount of frost-heave that occurs in saturated sandy soil. The results show that the newly developed testing device accurately estimates the amount of frost-heave with error of < 8.69% between predicted and measured results for heaving pressure with freezing direction from top to bottom.

Longitudinal Deformation Model and Parameter Analysis of Canal Lining under Nonuniform Frost Heave

Due to the unique hydrothermal environments, the frost heave failure of the concrete lining of water conveyance canals in cold regions is still frequent. The deformation of lining after frost heaving and the stress distribution calculated by the mechanical model can be the reference for the lining design. However, previous research mainly focused on the mechanical model of the cross‐section while having little attention for the longitudinal nonuniform frost heave damage. In this study, a mechanical model of the bottom lining under the nonuniform frost heave deformation is built based on the Euler–Bernoulli beam and the Pasternak foundation model, and the analytical solution of the model is obtained. The internal stress of the lining is analyzed during the changes of subgrade coefficient, shear rigidity, transition section length, and frost heave amount inside the model. Also, the calculation process is proved to be correct. The result shows that dangerous cross‐sections are at the start and the end of the transition sections. The maximum normal stress and the tangential stress increase when the subgrade coefficient and the frost heave amount increase and the shear modulus and transition section length decrease. The frost heave amount in the frozen ground subgrade increases constantly, while the temperature decreases, but at the same time, the shear rigidity of the subgrade increases with it. The former increases the stress of lining, and the latter decreases it. Therefore, during the frost heaving process, the internal force of lining is coupled with these two elements. By analyzing a water conveyance canal lining under the nonuniform frost heave in the Xinjiang Tarim irrigation district, the maximum normal stress of the dangerous lining cross‐section is greater than its tensile strength when the transition section length smaller than 7 m at the frost heave amount is 0.031 m.

Predicting the frost heaving of bottom ash value for road design

Introduction. Most of the researchers dealing with the use of ash and slag materials (especially in the construction) have focused on the study of their mechanical characteristics or assessment of their impact on the environment. At the same time, the design of roads with embankments of soil materials in the Northern regions requires taking into account the behavior of materials in cold climates.Although ash and slag materials are a typical dispersed soil, it is prone to frost heaving (due to the peculiarities of the internal structure). In addition, these materials have not been sufficiently tested in the development of the Russian Federation standards and codes for road design. Therefore, the professional environment is developing a hypothesis about the inadmissibility of using ash and slag materials in road embankments due to excessive frost heaving of this material, which, in our opinion, is not the case.Methods of research. To obtain real values of ash and slag frost heaving, specialists of Siberian State Transport University carried out additional studies to determine the relative deformations of frost heaving of medium-grained samples and coarse-grained ash slabs. SibADI specialists compared the results obtained with earlier studies to determine the relative deformations of frost heaving of fine-grained ash slabs samples, and analyzed the entire array of data obtained.Results. As a result of joint work, an empirical model was obtained that makes it possible to predict the amount of frost heaving of ash and slag material depending on its degree of compaction, initial moisture content (when working in a closed circuit or moisture in freezing through an open system), particle size distribution and freezing temperature. This makes it possible to determine the degree of frost heaving of ash and slag systems based on the grain size composition and the calculated characteristics of the subgrade.