Frost Heave Research Articles

Deformation causes of the Embankment-Bridge transition section in warm permafrost: The case study of a dry bridge along the Qinghai-Tibet railway

Differential embankment settlement and expansion joint failure in the embankment bridge transition section (EBTS) are two main issues endangering the safety of the Qinghai-Tibet Railway (QTR) in permafrost. A better understanding of the causes of EBTS deformation can offer valuable guidance for engineering maintenance. In this study, a comprehensive field investigation and a series of simulations were carried out to reveal the formation causes. The results revealed significant permafrost degradation beneath the EBTS after 15 years of operation, with temperatures nearing the thawing point. Despite contact between the abutment and beam end, the expansion joint exhibited continuous narrowing, particularly during the cold season. Permafrost degradation was primarily attributed to the heating effect of adjacent bridge structures. Foundation ground settlement emerged as the primary cause of embankment settlement in the transition section, contributing up to 80 % of the total settlement. Differential embankment settlement of the EBTS primarily stemmed from the uneven warming or thawing of permafrost, induced by the thermal impact of the adjacent bridge structures. The weakening of the transition section had a concentrated impact on embankment settlement within a 12-meter span behind the abutment, inducing approximately 30 % to 50 % of the embankment settlement. The backfill soils near the abutment experienced severe lateral frost heave in cold seasons. Horizontal displacement of the abutment caused by the lateral frost heave was identified as the main reason for expansion joint failure. Additional cooling measures are necessary to ensure the long-term stability of the EBTSs along the QTR, considering the faster degradation of ambient permafrost than expected. The findings offer valuable insights for the maintenance and design of railways in permafrost regions.

Discussion of “Experimental and Numerical Investigations of Frost Heave Characteristics of a Transmission Tower Foundation along the Lanzhou–Lintao Power Transmission Line”

Discussion of “Experimental and Numerical Investigations of Frost Heave Characteristics of a Transmission Tower Foundation along the Lanzhou–Lintao Power Transmission Line”

Fracturing behavior and damage model of spatial-rotation fissured sandstone: An experimental study on freeze–thaw and fatigue loads coupling

Earthquake exposure can greatly weaken the mechanical properties and affect the failure process of fractured rocks in cold regions. Creep tests of the spatial-rotation (SR) fissured rock with sandstone as the bedrock under different fatigue combinations and angles were carried out. The effects of freeze–thaw and fatigue loads (FT-FLs) on the deformation behaviour of samples, for example, creep, fatigue deformation, frost heave pressure, and creep rate, were explored. The mechanical responses and failure modes of the specimens were analysed in detail. Based on the experimental results, a new coupled damage model was explored. The results show that in addition to the typical creep stage, the rheological curve also included the phase of disturbance deformation under fatigue loading. The attenuation rates of the rock samples had downward trends with increasing load level under the fatigue combinations and angles, and these decreasing trends had linear characteristics. Moreover, the fatigue rate values increased gradually as the fatigue amplitude, fissure angle and rotation angle increased. In addition, with the change in the fissure and rotation angles, the curves of the tensile crack number had inverted U-shaped trends. The 3D fracture patterns under fatigue were dominated by vertical and vertical-lateral penetration, in which secondary fissure expansion also occurred at different angles. A combined damage model based on the damage variable of freeze–thaw cycles, fatigue loading, and spatial rotation of fissures was established. Compared with test data and other models, the coupled model has good accuracy in describing the entire failure process of specimens under FT-FLs and provides a new framework for the stability of fractured rock masses.

Mechanical analysis of frost heaving of weakly cemented soft rock tunnels in cold regions

To reveal the mechanical response of non-uniform frost heave of surrounding rock in soft rock tunnel in cold region, the stress solution of frozen surrounding rock considering the temperature field was deduced by applying elastic mechanics' displacement potential theory and the superposition principle. Then the plastic zone evolution of frozen surrounding rock was clarified by using the limit equilibrium approach. Furthermore, the analytical solution is verified with the existing solutions, and proved to be reasonable. The calculation results showed that as the temperature drops, the growth rate of the frozen zone radius gradually slows down while the stress increment increases. Frost heaving effect lead to a decrease in the critical state value of the lateral pressure coefficient (λ) for tension–compression. Circumferential stresses show a significant stress drop at the frozen boundary, and radial stresses show extreme values. Frost heaving enlarges the circumferential range of the plastic zone. Under low initial vertical stress conditions (p), when λ or 1/λ decreases from 1 to 0, the plastic zone gradually increases, while its range is always in the frozen zone. However, with an increase in “p” and a decrease in temperature to a certain extent, both inner and outer plastic zones emerged.

Model Test Investigation of Pipe-Soil Interaction under Frost Heave Conditions of Roadbed

Model Test Investigation of Pipe-Soil Interaction under Frost Heave Conditions of Roadbed

Study on the formation mechanism and preventive measure of pot cover effect for subgrade in seasonal frozen soil area under freeze–thaw cycles

AbstractThe presence of an impervious cover layer inhibits the free evaporation of moisture in the soil during seasonal freeze–thaw cycles, leading to a phenomenon known as the pot cover effect. This can result in severe frost heave issues in airport runways, highway subgrades, railway subgrades, and other similar infrastructure. In this study, a disease investigation was conducted at a gas transmission station situated in an area with seasonally frozen soil. Meanwhile, the causes of moisture accumulation and frost heave in the lower part of concrete pavement slabs were analyzed. A coupled water–vapor–heat model for unsaturated frozen soil is then established to analyze the formation mechanism of the pot cover effect in the subgrade. Finally, the preventive effect of the impervious layer on moisture migration in the pot cover effect was analyzed. The results indicate that the pot cover effect causes a significant accumulation of moisture beneath the concrete pavement at the gas transmission station, resulting in a moisture content increase of 5%–35%. During the freezing period, the vapor of shallow soil migrates upward, while the liquid water remains unchanged. During the melting period, both vapor and liquid water migrate downward. The laying of the impervious layer can prevent moisture migration of the pot cover effect. When the impervious layer is placed on the freezing front (0°C), the prevention effect of the pot cover effect is the best.

Assessment of Frost Depth and Frost Heave in Romania

The investigation of extreme weather and climate events has gained momentum in the last few decades, spurred in part by political involvement. However, not enough attention has been paid to the historical recorded data of climate monitoring. An accurate estimate of maximum soil frost depth is an important factor in determining construction costs and structures’ foundations, and designers also need reliable information about local meteorological parameters. In this study, the calculations of the parameters for the city of Arad are presented as an example. An updated Romanian frost depth map and a new Romanian freeze–thaw cycle (FTC) map are needed since recent climate studies have documented an increase in global and regional surface temperatures, with the greatest shift in warming occurring over the last three decades. This trend is particularly pronounced when comparing the 1990–2020 period with earlier periods, which could be indicative of broader climate change trends. It is important to note that these conclusions are based solely on the provided statistical parameters and do not take into account other potential factors influencing temperature trends in the region. The results from this investigation could be used to achieve a reduction in frost disasters and the formulation of policies and measures for the adaptation of geotechnical/structural design for Romanian territory. They may also support the development of maps that help to visualize and understand the evolving climate patterns in the region, including changes in frost depth and the frequency of freeze–thaw cycles, which are important for various sectors such as agriculture, construction, and infrastructural planning. Given the documented increase in global and regional surface temperatures, updating such maps will also provide valuable information for policymakers, researchers, and stakeholders on how to adapt to ongoing climate change and its impacts on the Romanian region.

Laboratory study on the frost-proof performance of a molecular vibration infrared Nano-thermoprobe (MVINT) embankment in seasonally frozen ground regions

Frost heave significantly affects the stability of embankment in seasonally frozen ground regions. Most previous studies focused on the investigation of the passive method for controlling or mitigating frost heave, but its effectiveness diminishes with time. Therefore, proactive method is proposed to address frost heave. In this study, a novel embankment with molecular vibration infrared nano-thermoprobe (MVINT) was designed. The performance of an embankment with MVINT and an embankment without MVINT were compared. During the freezing-thawing process, we monitored temperature, volumetric unfrozen water content and deformation fields. The results show that the MVINT significantly improves the temperature of the embankment. For the embankment with MVINT, its whole temperature is above 0 °C, while the temperature of the lower part of the embankment without MVINT is above 0 °C in the cold seasons. Meanwhile, the variations of volumetric unfrozen water contents for the embankment without MVINT are more significant compared to the embankment with MVINT at the same position. Furthermore, the vertical deformation at the road surface is significantly reduced for the embankment with MVINT. It is because the MVINT releases warm energy in the cold periods, which effectively reduces frozen depth and mitigates frost heave. Therefore, the MVINT could be used to control and mitigate the frost heave of embankment in seasonally frozen ground regions.

A unified model for frost wedging in an open fissure under unidirectional freezing

The propagation of joints and fissures, included by the frost heaving pressure arising from the water-ice phase transition is considered as frost wedging. This process is widely observed and plays a crucial role in weathering of jointed hard rocks in cold regions. Despite some fundamental results achieved in former experimental studies, a unified theoretical model is still absent, hindering a thorough understanding of this process. To further explore the mechanism of frost wedging during the freezing process, this paper firstly carries out a frost heave test on a rock block bearing a single open fissure. The results indicate that the evolution of frost heaving pressure in the fissure can be divided into four stages: sealing of the open fissure by ice wedge, ice wedge slipping, crack propagation, as well as stabilization of the ice-filled fissure. Based on the laboratory test results, a unified model for the frost heaving pressure in a single open fissure is established, which comprehensively takes into account the mechanical interaction between ice, water and rock. The model is validated by the test result, and it can reasonably describe the formation of the sealing conditions and the process of crack propagation. Fracture of the ice-rock interface near the free surface increases the likelihood of ice wedge slip, while frost wedging mainly damages geological bodies during crack propagation.

Experimental study on progressive interfacial mechanical behaviors using fiber optic sensing cable in frozen soil

Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction. Optical frequency domain reflectometry (OFDR) based on Rayleigh scattering can be applied to monitor ground deformation in frozen soil areas, where the interface behavior of soil-embedded fiber optic sensors governs the monitoring accuracy. In this paper, a series of pullout tests were conducted on fiber optic (FO) cables embedded in the frozen soil to investigate the cable‒soil interface behavior. An experimental study was performed on interaction effects, particularly focused on the water content of unfrozen soil, freezing duration, and differential distribution of water content in frozen soil. The high-resolution axial strains of FO cables were obtained using a sensing interrogator, and were used to calculate the interface shear stress. The interfacial mechanical response was analytically modeled using the ideal elasto‒plastic and softening constitutive models. Three freezing periods, correlating with the phase change process between ice and water, were analyzed. The results shows that the freezing effect can amplify the peak shear stress at the cable-soil interface by eight times. A criterion for the interface coupling states was proposed by normalizing the pullout force‒displacement information. Additionally, the applicability of existing theoretical models was discussed by comparing the results of theoretical back‒calculations with experimental measurements. This study provides new insights into the progressive interfacial failure behavior between strain sensing cable and frozen soil, which can be used to assist the interpretation of FO monitoring results of frozen soil deformation.

A new measurement method of volumetric frost heave deformation of freezing soil under complex pressure and constraint conditions

Preventing and controlling frost heave deformation is critical to artificial freezing construction. Compared to road engineering, the soil experienced complex pressure and constraint conditions during the freezing process. Therefore, this study introduces a new method for measuring the volumetric frost heave coefficient (VFHC) of freezing soil under complex pressure and constraint conditions. Series experiments were performed to validate the method and explore the pressure effects. Experimental results demonstrate that this method consistently produces stable and well-reasoned outcomes, providing valuable reference for the development of specialized three-dimensional frost heave testing apparatus in subsequent research. Furthermore, this research reveals that pressure and constraint conditions have a significant influence on the volumetric frost heave deformation of soil. An empirical equation that describes the variation of the VFHC with moisture content, considering the pressure and constraint effects, was proposed. These findings have significant implications for underground engineering employing the artificial ground freezing method.

Effect of freeze-thaw cycles on water permeability of sand mixtures with nanoclay

The mixtures of sands and nanoclays are used to isolate municipal and industrial solid wastes. Compared with natural clayey soils, these mixtures are characterized by homogeneous composition, workability, and low compressibility. This study investigated the effect of freeze–thaw cycles on their permeability. The mixtures of four sands and a saponite clay suspension generated by diamond ore processing were studied. The mixtures were prepared on the basis of 4 % and 8 % clay from sand weight. The tests were performed using an apparatus consisting of four devices for measuring frost heave and permeability, which were placed in containers with water. The water level was decreased gradually to ensure sample freezing or increased to ensure sample thawing. The frost heave of the mixtures with 4 % clay was 10.0–16.4 % under an external load of 2 kPa, and the five freeze–thaw cycles resulted in an increase in the hydraulic conductivity by 2.0–4.7 times. The mixtures with 8 % clay were tested under a load of 12 kPa, because of their high frost susceptibility. The hydraulic conductivity increased by approximately the same value as in the first case, i.e., by 1.2–2.0 times. The experiments have shown that the examined mixtures are suitable for isolating wastes. However, to eliminate the above effect, a waterproof liner should be covered with inert soil, which would reduce the depth of frost penetration and apply the load on it.

Frost heave model and frost heaving force analysis of permafrost tunnel based on segregated ice

Bi-directional freezing occurs when a tunnel portal passes through an active layer in cold region, or when the tunnel passes through permafrost. The surrounding rock of tunnel portal is frozen by air inside of the tunnel and earth surface. The freezing-thawing cycle of permafrost tunnels is frozen by the permafrost and air inside the tunnel. To investigate the frost heave force on the lining of permafrost tunnels, and verify the layered segregation ice in the surrounding rock of these tunnels, a one-dimensional hydrothermal stress model of bi-directional freezing is established, so as to study the evolution law of segregated ice from the surrounding rock in permafrost tunnels based on the theory of hydro-thermal coupling and segregated ice. After that, based on the mechanical theory, a frost-heave elastic mechanical model including secondary lining, freeze–thaw zone, freezing zone and segregated ice is established. The results show that there is layered segregated ice in the surrounding rock after the lining of permafrost tunnel. The annual difference and the annual average temperature have a great influence on the thickness of segregated ice, while the influence of thermal conductivity is relatively small. The thickness of thawing cycle should be less than 5 m, so that the frost heaving force acting on the lining will not be too large. Good water plugging quality can decrease the thickness of segregated ice. The frost-heaving force acting on the lining increases as the thickness of segregated ice increases. When the thickness of segregated ice is 10 cm, the maximum frost heaving force generated on the lining of single-layer segregated ice is 1.39 times that of non-segregated ice. The frost-heaving force caused by the segregated ice should be considered to guarantee the safety of tunnel structure.

Calculation and numerical modeling of the effect of heat and mass transfer on the properties of pile foundations in seasonally freezing soils

The phenomenon of heat and mass transfer in seasonally freezing soils has a significant impact on the condition of pile foundations. Building structures constructed in such soils experience extremely negative consequences: frost heave, vibration dynamics, moisture mass transfer and soil weakening during the thawing. Seasonally freezing soils occupy most of the territory of Kazakhstan, and in most regions the depth of soil freezing exceeds 1.5 m, there are settlements where the index reaches 1.97 m (Semiyarka, East Kazakhstan region) and in the north of the country - 2.74 m (Arshaly, Akmola region). Arrangement of foundation bases below the frost depth leads to increased construction costs, requires additional costs for thermal insulation, ventilation, other materials and structures, and, in addition, does not always lead to a full levelling of the negative impact of heat and mass transfer on the term and conditions of operation of buildings, structures, railways and roads. Therefore, the efforts of engineers and specialists in the field of thermal physics are aimed at finding effective ways to solve the problems of deformation and destruction of foundations in seasonally freezing soils. In the article an attempt is made to reveal the character of heat and mass transfer influence on pile foundations in seasonally freezing soils on the basis of a thermomechanical model.

Insights into the thermal insulation capability of a new polyurethane polymer subgrade material: An in-situ field test on the Qinghai–Tibet highway

The frost heave and thaw settlement of subgrades in permafrost regions severely threaten highway safety during repeated freeze–thaw cycles. However, these freeze–thaw cycles are difficult to overcome because of the lack of thermal insulation materials (or structures). To fill this gap, we developed a polyurethane (PU) polymer material with low thermal conductivity and designed a double–layer PU–grouted structure. The water–vapor–thermal coupling governing equations of the grouted subgrade were established. A numerical simulation was conducted using the finite element software COMSOL Multiphysics. Ten-month in-situ tests were conducted on the Qinghai–Tibet Highway from November 2021 to August 2022 to investigate the thermal insulation properties of the grouted subgrade. The results indicated that the PU exhibited excellent thermal insulation performance and considerably reduced the disturbance depth of the air temperature. Freeze and thaw depths were reduced by 0.65 and 1.65 m, respectively. During the freeze period, the surface and deep layers of the subgrade showed a temperature difference of 6 °C due to the upper PU layer, preventing 32.4 % of the liquid water from being frozen. The upper PU layer caused a temperature difference of up to 7 °C between the surface and the deep layers of the subgrade during the thawing period. Water evaporation was prevented by the upper PU layer, and water gathered between the grouted layers, which was defined as the “pot-cover effect.” The pot cover effect significantly reduced the soil temperature and maintained a stable temperature in the deeper subgrade during thawing.

Long-term freeze–thaw cycle behavior of high-speed railway embankment in frozen soil regions and its effects on train-track dynamic interaction system

The high-speed railway embankment built in cold regions has a long-term freeze–thaw cycle behavior, and the frost heave of soil will inevitably affect the smoothness of the track structure laid on the embankment, resulting in the deterioration of the train running performance and the dynamic behavior of the ballastless track system. This work is motivated by the research to investigate the long-term freeze–thaw behavior of the embankment in frozen soil regions and its effects on the train-track dynamic interaction system. Based on this motivation, the temperature-deformation field model of the embankment and the train-track dynamic interaction model (TTDIM) are established as an integrated model. The additional track irregularity triggered by the frost heave deformation of the embankment is regarded as the excitation source in the TTDIM to achieve the co-analysis of two sub-models. Through an illustrative example, the evolution characteristics of the freeze–thaw cycle behavior of embankment is fully revealed. Moreover, the effects of time-varying frost heave deformation of embankment on the performance of train-track interaction are quantified from the aspect of representative responses and safety evaluation indexes. This paper provides a valuable model and research thought reference for the analysis and assessment of the performance of train-track interaction under the long-term freeze–thaw cycles of the embankment in frozen soil regions.

Measurement and Modeling of Thermo-Hydro-Mechanical Behaviors of Frozen Clays: Frost Susceptibility and Compressibility

The risk of geohazards associated with frozen subgrades is well recognized, but a comprehensive framework to evaluate frost susceptibility from microstructural characteristics to macroscopic thermo-hydro-mechanical (THM) behaviors has not been established. This study aims to propose a simple framework for quantitatively assessing frost susceptibility and compressibility in frozen soils. A systematic THM model was devised to predict heat transfer, soil freezing characteristics, and stress states in frozen soils. Constant freezing experiments and oedometer compression tests were performed on bentonite clays under varying temperatures (−5°C, −10°C, and −20°C) and stress levels to validate the proposed model. Additionally, soil electrical conductivity measurements were employed to assess the temperature- and stress-dependent volumetric and mechanical properties of frozen soils. The model used Fourier’s law to compute the transient soil temperature profile and estimated the volume change and stress states based on the soil freezing characteristic curve. Experimental results showed that frost heave of bentonite reached between 9.0% and 26.6% of axial strain, which was largely predicted by the proposed model. It also demonstrated that the frost heave was mainly attributed to the fusion of the porewater. Additionally, the preconsolidation pressure of frozen soils exhibited a rapid increasing trend with decreasing temperature, which was explained by the temperature-dependent ice morphology in the soil interpore. Furthermore, the findings also demonstrated a remarkable sensitivity in the electrical conductivity in response to the soil temperature during the frost heave process and the stress state under the loading or unloading path.

Elasto-plastic solution for frost heave force considering Hoek-Brown criterion and freezing temperature gradient in cold region tunnels

The tunnel frost heave force is a primary cause of frost damage in cold region tunnels. To guide the prevention and treatment of tunnel frost damage, an elastic–plastic solution for the frost heave force is proposed based on the nonlinear Hoek-Brown (H-B) strength criterion. The elastic–plastic calculation model for the frost heave force simultaneously considers the variation of the volumetric frost heave strain of the surrounding rock with the freezing temperature and the uneven frost heave linear strain. The elastic–plastic analysis of the tunnel frost heave force and development of plastic damage in rock masses based on the H-B criterion is performed through engineering examples in cold regions. The frost heave force of Dabanshan Tunnel obtained by the H-B criterion elastic–plastic solution is 1.14 MPa, which is basically consistent with the monitoring values. The plastic radius is 5.72 m. But the calculation using the linear strength criterion results in a smaller frost heave force and a larger plastic zone radius. And the corresponding parameters of the H-B criterion directly use the rock mass parameters in the survey report, which is convenient for engineering application. The parameter analysis reveals that the plastic zone and frost heave force gradually increase with decreasing GSI and increasing disturbance parameter D. The degree of disturbance has a significant effect on the frost heave force and the plastic zone radius, and is an influencing factor that cannot be ignored.

Numerical Study of Pore Water Pressure in Frozen Soils during Moisture Migration

Frost heaving in soils is a primary cause of engineering failures in cold regions. Although extensive experimental and numerical research has focused on the deformation caused by frost heaving, there is a notable lack of numerical investigations into the critical underlying factor: pore water pressure. This study aimed to experimentally determine changes in soil water content over time at various depths during unidirectional freezing and to model this process using a coupled hydrothermal approach. The agreement between experimental water content outcomes and numerical predictions validates the numerical method’s applicability. Furthermore, by applying the Gibbs free energy equation, we derived a novel equation for calculating the pore water pressure in saturated frozen soil. Utilizing this equation, we developed a numerical model to simulate pore water pressure and water movement in frozen soil, accounting for scenarios with and without ice lens formation and quantifying unfrozen water migration from unfrozen to frozen zones over time. Our findings reveal that pore water pressure decreases as freezing depth increases, reaching near zero at the freezing front. Notably, the presence of an ice lens significantly amplifies pore water pressure—approximately tenfold—compared to scenarios without an ice lens, aligning with existing experimental data. The model also indicates that the cold-end temperature sets the maximum pore water pressure value in freezing soil, with superior performance to Konrad’s model at lower temperatures in the absence of ice lenses. Additionally, as freezing progresses, the rate of water flow from the unfrozen region to the freezing fringe exhibits a fluctuating decline. This study successfully establishes a numerical model for pore water pressure and water flow in frozen soil, confirms its validity through experimental comparison, and introduces an improved formula for pore water pressure calculation, offering a more accurate reflection of the real-world phenomena than previous formulations.

Foundations in Permafrost of Northern Canada: Review of Geotechnical Considerations in Current Practice and Design Examples

In northern Canada where permafrost is prevalent, a persistent shortage of accessible, affordable, and high-quality housing has been ongoing for decades. The design of foundations in permafrost presents unique engineering challenges due to permafrost soil mechanics and the effects of climate change. There is no specific design code for pile or shallow foundations in northern Canada. Consequently, the design process heavily relies on the experience of Arctic engineers. To clearly document the current practice and provide guidance to engineers or professionals, a comprehensive review of the practice in foundation design in the Arctic would be necessary. The main objective of this paper is to provide an overview of the common foundations in permafrost and the geotechnical considerations adopted for building on frozen soils. This study conducted a review of current practices in deep and shallow foundations used in northern Canada. The review summarized the current methods for estimating key factors, including the adfreeze strength, creep settlement, and frost heave, used in foundation design in permafrost. To understand the geotechnical considerations in foundation design, this study carried out interviews with several engineers or professionals experienced in designing foundations in permafrost; the findings and the interviewees’ opinions were summarized. Lastly, in order to demonstrate the design methods obtained from the interviews and review, the paper presents two design examples where screw piles and steel pipe piles were designed to support a residential building in northern Canada, according to the current principles for adfreeze strength, long term creep settlement, and frost heave. The permafrost was assumed to be at −1.5 °C, and the design life span was assumed to be 50 years. The design examples suggested that for an axial load of 75 kN, a 12-m-long steel pipe pile or a 7-m-long screw pile would be needed.