Frost Heave Rate Research Articles

Study on Frost Heave and Thaw Settlement Characteristics of Sanya Estuary Channel Soil Layer

In order to explore the frost heave and thaw settlement characteristics of soil layers in the Sanya Estuary Channel Project, the frost heave rate and thaw settlement coefficient of gravel sand, fine sand, silty clay, and clay are obtained. The most unfavorable soil layers are then compared and analyzed. The variation law of frost heave and thaw settlement performance of the most unfavorable soil layer under different water content is studied. The results are as follows: (1) The freezing stage of the passage through the typical soil layer is divided into four stages: frost shrinkage, rapid frost heave, slow frost heave, and frost heave stability. The melting stage is divided into three stages: slow thaw settlement, rapid thaw settlement, and thaw settlement stability. (2) The most unfavorable soil layer in the typical soil layer of the Sanya Estuary Channel Project is silty clay, with a frost heave rate and thaw settlement coefficient of 4.51% and 5.88% at −28 °C. (3) The frost heave and thaw settlement performance of the most unfavorable soil layer is linearly related to water content. The larger the water content, the greater the frost heave rate and thaw settlement coefficient, and the more prone to damage.

A Quasi-Steady Model for Estimating the Rate of Frost Heave When Subjected to Overburden Pressure

The soil beneath buildings constructed in cold regions is affected by frost heave, causing the walls to crack and even the buildings to incline and collapse. Therefore, predicting the frost heave when subjected to overburden pressure is crucial for engineering buildings in cold areas. Utilizing the conservation equation of mass, Darcy’s equation, and the assumption that the pore water pressure at the top of a frozen fringe, denoted as uw, during the quasi-steady state can be approximately estimated using the Clapeyron equation, a quasi-steady frost heave rate model considering the overburden pressure was proposed. This study considered the difference in pore water pressure within the frozen fringe, which causes water to move from the unfrozen zone to the ice lens, where it subsequently accumulates and freezes into ice. The pore water pressure at the bottom of the frozen fringe, denoted as uu, can be estimated using the soil water characteristic curve (SWCC). The thickness of the frozen fringe was determined using the freezing temperature, segregation temperature, and temperature gradient. The segregation temperature was determined using the two-point method. Additionally, the model suggested that, when uw = uu, the movement of water stopped, leading to the end of frost heave. To validate the proposed model, three existing frost-heaving experiments were analyzed. The findings demonstrated that the estimated rates of frost heave of the samples closely matched the experimental data. Additionally, external pressure delayed water migration. This study can offer theoretical support for building engineering in cold regions.

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.

Modeling temperature change and water migration of unsaturated soils under seasonal freezing-thawing conditions

Frost heave and thawing settlements of seasonally frozen soil have a direct impact on the stability of engineered ground in cold regions. On the basis of the theory of seepage and heat conduction of unsaturated soil, a coupled thermal-hydro-mechanical numerical model of frozen soil was established. The alignment of experimental testing outcomes with numerical simulation results confirms the model's precision. The research findings indicate that the duration of freezing emerges as the primary factor influencing seasonal frost heave, with the soil frost heave rate ranging from approximately 1.5% to 3.3%. Within a period of 45 to 60 days following the conclusion of the freezing period, the ground height will return to its pre-freezing level. Construction of foundations in Daqing between late May and mid-October can help mitigate the damage caused by frozen soil. The variation laws of hydrothermal migration and frost heave in seasonally frozen soil have been summarized. The obtained results offer guidance for predicting soil frost heave and designing frost-heaving-sensitive engineering projects in cold regions.

Effects of transient temperature gradient on frost heave of saturated silty clay in an open system

Frost heave in seasonally frozen regions is a one-dimensional process that could severely damage infrastructure subgrades. Stress state, temperature and water migration are important factors for frost heave. This work investigated the effects of soil temperature and volumetric water content on the transient frost heave ratio during the freezing of saturated silty clay in an open system and analyzed the relationships between the transient frost heave ratio and freezing rate and between temperature gradient and frost heave rate. The results show that the frost heave ratio, frost heave rate, and freezing rate are positively correlated with the temperature gradient since the temperature gradient drives the water migration during freezing, indicating the transient temperature gradient could be used to evaluate the frost heave of saturated silty clay. The transient freezing rate and transient frost heave ratio are logarithmically related to the transient frost heave ratio and transient temperature gradient, respectively. The effects of transient temperature gradient on frost heave are the principal mechanism responsible for different frost heave characteristics and uneven frost heave along a subgrade of the same soil type.

Physical and Mechanical Properties of Expanded Polystyrene (EPS) Particle Lightweight Soil under Freeze-Thaw Cycles.

In seasonally frozen regions, the bearing capacity of soil decreases and gradually deteriorates after undergoing freeze-thaw cycles. To resolve this problem, based on the idea of frost-resistant filling materials, a filling scheme of expanded polystyrene (EPS) particles lightweight soil in cold regions was proposed. Unconfined compressive strength, direct shear, and micro-SEM tests were carried out to study the physical and mechanical properties of EPS particles lightweight soil under freeze-thaw cycles. The results indicate that the EPS particle lightweight soil has good frost resistance and can be used as frost-resistant filling material in cold regions. Under freeze-thaw cycles, EPS particle lightweight soil maintains good integrity; EPS particles can effectively reduce the frost heave rate, mass loss rate, and compressive strength loss rate of lightweight soil. The compressive strength depends on the EPS and cement contents: it decreases with an increase in the EPS content and increases with an increase in the cement content. The strength loss rate decreases with an increase in both. When the content of EPS is larger (more than 2%), the soil cement bound with EPS particles is limited, and the performance of lightweight soil decreases. The shear strength and cohesion decrease with an increase in freeze-thaw cycles and EPS content, and the internal friction angle follows no obvious rule with regard to the increase in freeze-thaw cycles but decreases with an increase in the EPS content. Based on the experimental results, an empirical formula for the compressive strength of EPS particle lightweight soil under freeze-thaw cycles was proposed. This study can provide a reference for the engineering design and application and provide new ideas for resolving freeze-thaw problems in construction engineering in cold regions.

A thermomechanical model for frost heave and subglacial frozen fringe

Ice-infiltrated sediment, or frozen fringe, is responsible for phenomena such as frost heave, ice lenses and metres of debris-rich ice under glaciers. Understanding frozen fringes is important as frost heave is responsible for damaging infrastructure at high latitudes and sediment freeze-on at the base of glaciers can modulate subglacial friction, influencing the rate of global sea level rise. Here we describe the thermomechanics of liquid water flow and freezing in ice-saturated sediments, focusing on the conditions relevant for subglacial environments. The force balance that governs the frozen fringe thickness depends on the weight of the overlying material, the thermomolecular force between ice and sediments across liquid premelted films and the water pressure required by Darcy flow. We combine this mechanical model with an enthalpy method that conserves energy across phase change interfaces on a fixed computational grid. The force balance and enthalpy model together determine the evolution of the frozen fringe thickness and our simulations predict frost heave rates and ice lens spacing. Our model accounts for premelting at ice–sediment contacts, partial ice saturation of the pore space, water flow through the fringe, the thermodynamics of the ice–water–sediment interface and vertical force balance. We explicitly account for the formation of ice lenses, regions of pure ice that cleave the fringe at the depth where the interparticle force vanishes. Our model results allow us to predict the thickness of a frozen fringe and the spacing of ice lenses in subaerial and subglacial sediments.

Experimental Study on Engineering Characteristics of High-Speed Railway Subgrade Filler in Island Permafrost Regions

The high-speed railway (HSR) subgrade has a strict settlement-control standard at the mm level, but its deformation stability is significantly threatened on permafrost with poor thermal stability and in susceptible-to-thawing settlements. Therefore, the filler suitable for permafrost regions needs to be explored and determined. In this study, the frost heaves, permeabilities and static strength characteristics of three coarse fillers were experimentally investigated, and the optimal subgrade filler was determined for the certain HSR, the first HSR in permafrost regions around the world. The test fillers include pure fillers, 5% cement improved fillers and 5% cement + 3% modifier improved fillers, and the effects of curing time, modifier content and freeze–thaw cycles were analyzed. The test results show that: (1) the frost heave rate and permeability coefficient decrease with the increase of curing time and modifier content, while increasing with the freeze-thaw cycles; (2) After six freeze–thaw cycles, the cement + modifier improved filler’s frost heave rate and permeability coefficient are 0.51 and 0.00331 cm/s, a larger decrease in the frost heave rate (more than 50%) and the permeability coefficient (about one order of magnitude) than that of pure filler; (3) The cement + modifier improved filler shares the highest compressive strength under different curing times and freeze-thaw cycles. In summary, the modifier has a more significant influence on the engineering characteristics than the curing time or freeze-thaw cycles, and the cement + modifier improved filler has the best comprehensive performance. This study will provide a technical reference for the foundation-treatment and disease-prevention of HSRs in island permafrost regions.

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.

A new criterion for vapour induced ice lens initiation in coarse-grained soils

Vapour migration and condensation into ice have been found to be the main reasons for frost heave in coarse-grained soils. The mechanism of this kind of frost heave is less understood than the traditional one due to condensation of liquid water. In particular, an accurate mathematical criterion is required to explain when and where the ice lens will form in coarse-grained soils. This study focuses on the migration of vapour from a mesoscale point of view. Mechanical equilibrium on the vapour-ice interface is discussed, and the rate of frost heave is acquired theoretically. A new criterion for ice lens initiation is proposed by analysing the forces acting at the vapour-ice interface. The influence of the overburden pressure and temperature gradient on the heaving rate is discussed. The new criterion provides a theoretical basis to understand frost heave in coarse-grained soils and can be used in numerical models for simulating frost damage in cold regions.

A study of the insulating and anti-frost heave effects of polystyrene boards under molded bag concrete conditions

Abstract In this study, the channel frost heaving actions in the Hetao irrigation area of Inner Mongolia were examined and a field in-situ test platform was established. Then, experimental investigations were conducted regarding the insulating and anti-freeze effects of polystyrene boards under the conditions of concrete bags with different thicknesses. In this study's experiments, concrete bags with different thicknesses were set, along with a test block of polystyrene boards with different thicknesses. The research results showed that by adding 2–5 cm molded bags, the total accumulated temperature increased in the range of 3.93–9.22% and the frost heave rate decreased by between 18.28 and 55.44% concrete, on the basis of 10 cm molded bag concrete. In addition, when 4–8 cm polystyrene boards were laid, the total accumulated temperature increased by 207.63–272.25%, and the frost heave rate decreased by between 71.43 and 96.6%. The absolute slope of the curve fitting of the frost heave rates and the soil temperatures decreased by 44.6–58.7%.

Centrifuge modelling of gas pipelines undergoing freeze–thaw cycles

Frost heave and thaw settlement are two critical factors that need to be considered in the design of chilled gas pipelines in cold regions. Due to the variation in seasonal temperature and operating conditions (e.g., pressure and temperature at the compressor stations), the pipeline temperature in some segments might vary from subzero to above zero during winter and summer, respectively. This study examines the freezing and thawing for cyclic and constant temperatures at the pipeline and ground surfaces based on the response of 14 model pipes tested in a geotechnical centrifuge. The cyclic (temperature) operation reduces the frost heave rate per year and causes net settlement in some cases. When the thaw bulb resulting from an above-zero operating temperature is less than the previously developed frost bulb, upward water flow occurs through the thawed soil, which could alter the pipeline–soil interaction behaviour. Five types of freeze-thaw-induced vertical displacement of the pipe have been identified from the centrifuge test results.

A thermal–hydromechanical coupled model for poro-viscoplastic saturated freezing soil

Most existing thermal–hydromechanical (THM) models used to describe the process of frost heave assumed the freezing soil to be elastic. However, an inelastic constitutive model capable of reflecting the viscous constitutive behaviour of freezing soils should be considered. Based on the existing mathematical model, this study presented an improved mathematical model of coupled water, heat, and stress for saturated freezing soil, in which the soil was assumed to be elastic-viscoplastic and its viscoplasticity was modelled by means of a simple (linear) Norton–Hoff’s law. In addition, solid–fluid interface energy was considered to formulate the effective water and ice pressures and liquid–crystal equilibrium condition which can be used to explain the micro-cryosuction mechanism was adopted to replace Clapyron equation which were used in most existing models. To solve the nonlinear governing equations, numerical simulations were performed using COMSOL software. Finally, the improved model was validated by comparing its simulation results with reference model and the distribution curves of frost heave, temperature, water content and flux rate were discussed.

Pile—soil interactions in frozen soil foundations based on frost heave rate and soil stiffness variations

The frost heave rate and stiffness of soil in frozen soil foundations varies remarkably with the freezing depth under the influence of the freezing-end temperature, temperature gradient, and overburden stress. The stress level of frozen soil increases with increasing frost penetration, leading to greater stiffness and a smaller frost heave rate. In this work, the freezing-end temperature and temperature gradient are introduced to the traditional Takashi model via the frost heave layering method and the overburden stress is modified to establish an empirical prediction model of frost heave rate and stiffness. Analytical solutions of load transfer differential equation of single pile considering stiffness increase and frost heave rate decrease along the frost penetration are derived on the basis of the mechanism of pile–soil interactions. The calculation results are in good agreement with measured values, thus confirming the correctness of the analytical solution. Variations in frost heave rate and soil stiffness with increasing depth are then combined to form four models, and changes in axial force and tangential frost heave force as a function of frost penetration are calculated and analyzed on the basis of these models. Results show that calculation of the frost heave rate and stiffness of soil along the frost penetration depth according to normal values will significantly underestimate the axial force of on the pile.

Frost heave and thaw settlement of initially saturated-slurried and compacted-saturated materials

Soils and industrial waste in various geotechnical engineering applications are expected to experience freezing and thawing processes in various regions of the world where the winter and summer temperatures fluctuate between sub-zero and positive ambient temperatures. In this study laboratory tests were undertaken on three materials (Speswhite kaolin, Pegwell Bay soil and a cement kiln dust). A custom-made test set up was used to carry out the laboratory tests involving freezing and thawing processes. Initially saturated-slurried and compacted-saturated samples of the selected materials were subjected to one cycle of freezing and thawing to study the influence of material type and initial conditions on the one-dimensional frost heave and thaw settlement. The test results showed that the type of material and the initial conditions of the materials prior to the freezing process influenced the frost heave, frost heave rate, velocity of water flow, segregation potential, and thaw settlement. Compacted-saturated materials showed a tendency to exhibit a greater magnitude of frost heave as compared to their saturated-slurried counterparts.

Physical and Mechanical Performance of Frozen Rocks and Soil in Different Regions

The artificial freezing method is extensively used in the reinforcement of engineering strata in various regions for shaft excavation and subway connection channels. In this study, representative rock and soil strata from different regions were subjected to low‐temperature physical and mechanical performance tests. The results show that, compared with Cretaceous and Jurassic rock and soil strata, deep topsoil and shallow coastal topsoil have high water content, low thermal conductivities, high frost heave rates, and high freezing temperatures. In addition, the results show that, as the curing temperature decreases, the uniaxial compressive strengths and elastic moduli of deep topsoil and shallow coastal topsoil increase almost linearly. The strength of the sandy soil strata is the highest, followed by the cohesive soil strata, and the strength of the mucky soil and the calcareous clay is the lowest. The strength of the frozen wall and the waterproof requirements must both be taken into account in the freezing design. Deep Cretaceous and Jurassic rocks can have high strength of more than 5 MPa under normal temperature conditions. An increase in the uniaxial compressive strength and elastic modulus with decreasing curing temperature is mainly manifested within the range from the normal temperature to −10°C. The strength can reach more than 10 MPa at −10°C, and only the strength requirements of the frozen wall need to be considered in the freezing design. At low temperatures, deep topsoil and shallow coastal topsoil are dominated by the form of compression failure. The average failure strain at −10°C is typically greater than 5%. When excavating the strata, it is essential to pay attention to the effect of creep. The failure strain of deep Cretaceous and Jurassic rocks is between 1% and 2%, and the breaking and sudden collapse of surrounding rocks should be prevented.

Ice lens induced interfacial hydraulic resistance in frost heave

Frost heave and ice lens cause the failure of engineerings and change the soil structure in cold regions. It is known that the water migrates from the unfrozen zone to feed the ice lens, but the mechanism of water migration in the vicinity of the ice lens is not well understood. In this study, the water migration at the interface between the ice lens and soil particles is theoretically investigated. Pore water flows from the soil pores to the unfrozen film between the ice lens and soil particles to expands the integral ice lens. The kinetics of the microscopic flow in the unfrozen film produces the hydraulic resistance at the macroscopic interface between ice lens and soil particles. Based on the global mechanical equilibrium at the ice-water interface, the rate of frost heave is derived for freezing soils with and without a frozen fringe. An expression for the neutral stress in the frozen fringe is developed to predict the initiation of new ice lenses with considering the effect of anisotropic stress of ice. The impacts of overburden pressure, temperature gradient, and interfacial hydraulic resistance on the rate of frost heave are discussed. In a relatively thick frozen fringe, the interfacial hydraulic resistance is insignificant compared to the hydraulic resistance of frozen fringe. However, if the thickness of frozen fringe is less than a critical value the interfacial hydraulic resistance will play a dominant role in the frost heave. This research is expected to facilitate the improvement of frost heave models, studying the influence of the interfacial hydraulic resistance on the characteristic of frost heave with and without a frozen fringe.

The effect and parameter analysis of stress release holes on decreasing frost heaves in seasonal frost areas

Frost heave can be substantially reduced if frost deformation of seasonally frozen ground is allowed to occur to a certain extent in the lateral direction. This controlled process can be achieved with a new approach of using stress release holes (SRHs) to decrease the frost heave. Experiments were designed and conducted based on one-dimensional frozen soil samples in closed or open systems. After being frozen for 48 h or 72 h, the soil samples with and without SRHs were then compared for their differences in frost heave deformation, temperature, frost heave rate, and moisture migration. The effects of soil samples with different Hole Ratio in Area (HRA), SRHs, and SRH filling materials are also studied. Results show that when the compaction coefficient Kcc decreases, there is resulting increase in frost heave. Furthermore, with an increasing ratio of HRA, the deformation and the frost heave rate decreases. The maximum frost heave of saturated soil samples with filled SRHs can be effectively decreased in both open and closed systems. Consequently, SRHs with filling are an appealing treatment measure that can be taken to decrease the frost heave of seasonally frozen soils.

Frost Heave of Irrigation Canals in Seasonal Frozen Regions

Soil frost heave acts as a driver of the emerged fracture in the concrete lining of irrigation canals and subsequent water leakage in seasonal frozen ground. A model test was carried out on the frost heave of a U‐shaped canal with concrete lining. The heat and water migration during freezing, and frost heave‐induced deformation, and force in normal direction were live monitored by high‐precision transducers. The results prove that the freezing front descends downward over time at a specified thermal boundary, with considerable migration of water within the scope of 0–40 cm. The maximum deformation occurred at the bottom of the lining and decreased upward with the rate of frost heave lowering over time while the normal force showing little change in the monitoring points, implying that stress concentration does not show up during freezing. Besides, the layered settlement observation reveals that frost heave dominates the total deformation while creep, the universal source of deformation, accounts for a negligible proportion. A practical model was proposed based on a simple theoretical model for heat‐water coupled transfer in a partially saturated medium and was numerically implemented in COMSOL. The computed results were compared with the monitored data including frozen depth, water content, normal displacement, and frost heave force. Finally, the rational thickness of the insulation board was determined based on the partial insulation method.

Experimental study on dynamic cumulative axial-strain performance of freezing–thawing saturated sandy silt

Depending on artificial freezing method adopted in subway tunnel construction, a series of frost heave and stress-controlled cyclic triaxial tests were conducted on saturated freezing–thawing sandy silt to investigate their unconfined frost heave performance and plastic strain behavior. In terms of practical engineering, this study focuses on four significant influencing factors which are freezing temperature, dynamic stress amplitude, cell pressure and loading frequency. The results indicate that the remolding–stripping device provide an effective way for remolding soil sample, particularly dense sand and silt. Besides, the freeze–thaw action can truly has influence on the unconfined frost heave rate, and undisturbed or remolded soil with higher freezing temperature possesses smaller volume frost heave rate. In addition, the value of freezing temperature has significant influence on strain of remolded saturated freezing–thawing sandy silt with higher freezing temperature possesses larger accumulated axial strain, the accumulated plastic strain decreases remarkably with the increasing of dynamic stress amplitude and cell pressure, the loading frequency has considerable effect on accumulated axial strain of soil that is lower frequency can generate larger accumulated plastic strain. Finally, an improved semi-logarithmic empirical formula of cumulated permanent axial strain on freeing-thawing saturated sandy silt is proposed, and verified by experimental data, which could exactly forecasting development trend of dynamic permanent axial strain.