Frost Heave Pressure Research Articles

Initiation mechanism of landslides in cold regions: Role of freeze-thaw cycles

Freeze-thaw cycles are recognized as one of the key triggers for some major landslides in cold regions around the world. Though the effects of freeze-thaw cycles on the rock strength degradation have been studied extensively, little effort has been made to qualitatively evaluate how it contributes to the evolution from a stable rock slope to a large-scale mass movement. In this study, we use a discrete element-based numerical model to simulate the entire process of the initiation of landslide under the action of freeze-thaw cycles in a slope with randomly distributed initial cracks. The main goal of this work is to quantitatively describe the landslide evolution process regarding the slope displacement, crack propagation, stress chain and load-bearing structure. Our results show the essence of the displacement evolution of a landslide subjected to freeze-thaw cycles; namely frost heave pressure induces the generation of new cracks, leading to the failure and reconstruction of the load-bearing structure of the slope. Deep-seated landslides can occur when the slope is crossed by a fault; otherwise, the slope is prone to surface erosion or shallow landslides.

A frost heave pressure model for fractured rocks subjected to repeated freeze-thaw deterioration

Rock engineering in the Tibetan Plateau is usually suffered severe freeze-thaw (F-T) deterioration, triggering numerous geotechnical engineering disasters. As the essential triggering factor of F-T damage, the frost heave pressure (FHP) in rocks should be quantitatively described and predicted. In this study, a novel theoretical model is established and validated to estimate the critical entire evolution process of FHP in fractured rocks subjected to repeated F-T deterioration, in which the influence of fracture geometric configuration, rock mechanical properties and F-T conditions are comprehensively considered. Besides, given the obvious five-stage manner of FHP evolution, the combination effect of different dominant mechanisms in different stages is theoretically addressed. During freezing, after a silence stage induced by temperature above freezing point of water, volumetric expansion and frost-heave cracking separately controls the generation and reduction stages of FHP, and the solutions are obtained based on elastic mechanics and Griffith energy balance theory, respectively. During thawing, ice segregation dominates the second-arising stage of FHP that is quantitatively described via segregation potential and water migration velocity, and then the FHP enters the dissipation stage owing to complete melting of fracture ice. In addition, a decay coefficient is introduced to estimate the influence of F-T cycle number on FHP, and a piecewise FHP model is finally constructed for fractured rocks subjected to repeated F-T deterioration. To validate our new model, a total of 12 F-T cycle tests with real-time FHP monitoring are conducted on granite and sandstone specimens considering three typical influencing factors, i.e., fracture width, rock types and freezing temperatures. A rational consistency is identified between the theoretical and testing results in terms of the FHP evolution curves and the peak FHPs in rock fracture, demonstrating the generalizability and robustness of our proposed model.

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.

A numerical method to consider the interaction between multiple fractures in frozen rocks based on XFEM

The initiation, propagation, and coalescence of fractures in frozen rocks plays an important role in determining the deterioration and stability of the geotechnical engineering structure in cold regions. This study proposes a numerical method to consider the interaction of multiple fractures in frozen rock based on the volumetric expansion theory and extended finite element method (XFEM). The effective expansion coefficient is adopted in this paper to describe the volume change of ice-water mixture. To accurately determine the magnitude of frost-heaving pressure during the deformation and propagation of fractures, two iterative methods have been proposed. The correctness of the numerical method is verified by the analytical solution of frost-heaving pressure within a single fracture. In addition, the secant method shows the higher efficiency in solving the problems considering the fracture interaction. The evolution of frost-heaving pressure and cracking behavior under different geometric conditions were studied by the proposed method. The numerical results suggest that stress interference may promote the propagation of fractures and accelerate the deterioration of rock mass when the fractures are located in the favorable zone. After considering the multi-fracture interaction, the configuration of two fractures has a significant influence on the evolution of the frost-heaving pressure.

Mechanical behavior assessment of retaining wall structure due to frost heave of frozen ground

Frost heave action is a major issue in permafrost regions, leading to various geotechnical engineering problems. In this study, we assess the mechanical behavior of a concrete retaining wall subjected to frost heave under different ground conditions. The assessment utilizes ABAQUS integrated with several user subroutines. The numerical simulation model employs a thermo-mechanical coupled analysis with a porosity rate function, which enables to simulate time-dependent variations in porosity and frost heave of the backfill soil. After verification of the predictive reliability of the simulation model, the frost heave action in the soil and mechanical response of the retaining wall were evaluated regarding the initial groundwater level and presence of a drainage material on the backside of the retaining wall. According to the simulation results, as the initial groundwater level decreased in the backfill soil, the area susceptible to frost heave decreased. However, the von Mises stresses applied to the retaining wall increased. Under the same ground conditions, when the drainage material was installed on the backside of the retaining wall, the frost heave pressure acting on the wall significantly decreased, and less deformation and distortion of the retaining wall occurred.

Combined deterioration effects of freeze–thaw and corrosion on the cyclic flexural behavior of RC beams

Reinforced concrete (RC) stands as the predominant construction material, and with the growing prevalence of aging infrastructure, the safety assessment of deteriorating structures has emerged as a pressing and critical concern. This study presents an experimental investigation into the combined effects of freeze–thaw cycles (100, 200, and 300 cycles) and corrosion (corrosion ratio: 3% and 10%) on the cyclic behavior of RC beams. Seven RC beam specimens with varying types and levels of deterioration were fabricated, and static tests were conducted using a four-point bending method to assess the behavior of RC beams under each degradation factor. The experimental results revealed that increasing freeze–thaw cycles significantly impact RC beam behavior, leading to intensified crack formation due to cyclical frost-heaving pressure. This ultimately results in reduced yield loads ranging from 3% to 11% and peak loads reduced by 1–2% compared to the reference specimen A-0-0. Corrosion of steel bars in RC beams alters failure modes, with corroded specimens (C-0-3 and C-0-10) experiencing substantial decreases in yield load, a 15% reduction in C-0-3, and a 26% decrease in C-0-10, compared to A-0-0. Displacement at yield load and peak load also decreased, highlighting the detrimental impact of corrosion on beam mechanical properties. The combined deterioration from freeze–thaw cycles and corrosion further exacerbates these reductions, resulting in a substantial decrease in yield load (32%) and peak load (24%) in D-3-10 compared to the reference specimen A-0-0. Additionally, energy dissipation capacity and cumulative energy dissipation capacity exhibit dynamic changes influenced by the progression of freeze–thaw cycles, corrosion, and their combined effects.

Study on frost heaving force and the propagation of cracks in freezing rocks using the phase field method

In cold regions, the water in rocks expands volumetrically after freezing, leading to the propagation of fractures. In this study, the effective volume expansion coefficient is employed as a substitute for the volume expansion strain after the water in the fracture undergoes freezing and transforms into ice, and the phase field method is used to simulate the propagation of fractures in freezing rocks under various conditions to further explore the law of fracture propagation. The Abaqus software is used to solve the mechanical field control equation and the phase field evolution equation. First, the theoretical calculation of the frost-heaving pressure is compared with that obtained by experimental and numerical calculations. This comparison indicates that the numerical model presented in this study can effectively calculate the frost-heaving pressure during fracture propagation. Subsequently, the propagation of single and double fractures caused by frost heave is simulated based on fracture propagation experiments under frost heave conditions. The simulation results closely resemble the observed morphology of fracture propagation caused by frost heave obtained from the experiments. This confirms the suitability of the proposed model for simulating and predicting the propagation of fractures caused by frost heave. Finally, the influence of volume expansion strain growth path on fracture propagation due to frost heave is discussed. Although the final volume expansion strain value is the same, different growth paths of the volume expansion strain result in different fracture propagation morphologies.

Frost-heaving characteristics and formation mechanism of saturated sandstone under unidirectional freezing conditions

In this study, a series of frost-heaving experiments were conducted on saturated sandstone at varying cooling rates under unidirectional freezing conditions. The frost-heaving strain in the freezing process was examined using a novel laboratory testing methodology. The results showed that the frost-heaving behavior of the saturated sandstone was significantly affected by the freezing direction and rate. Specifically, the rapid freezing of sandstone parallel to the freezing direction resulted in a more pronounced frost-heaving strain than that perpendicular to the freezing direction. The rock freezing rate had a positive correlation with the peak frost-heaving strain parallel to the freezing direction, and a negative correlation with that perpendicular to the freezing direction. A microstructure-based conceptual model is proposed to determine the frost-heaving pressure. The conceptual model showed that the ice pressure, determined by the pore-water pressure and capillary force, resulted from the crystallization of the pore water within the pore structure. A nonlinear relationship was observed between the ice pressure and crystallization rate. Capillary forces were more significant for slow crystallization processes, resulting in a larger difference between ice and water pressures. At high crystallization rates, the hydraulic pressure acted on the pore structure before the capillary forces become significant, leading to a smaller difference between the water and ice pressures. Rapid crystallization processes resulted in the uneven distribution of ice pressure within the pore structure, with subsequent re-equilibration occurring with the migration of unfrozen water. The proposed conceptual model presents a new perspective for obtaining an improved understanding of the microscopic frost-heaving mechanism involved in the freeze-thaw damage of porous rocks. It provides an evaluation method for the behavior of rocks during weathering by frost heave in cold regions.

An Analytical Solution of Frost Heaving Pressure for Cold-region Tunnel Considering Freeze-thaw Cycles and in-situ Stress

The damage caused by the frost heaving pressure on the surrounding rocks and lining structure of cold-region tunnels is always common, which can seriously threaten the safety and stability for cold-region tunnels. Although many achievements of frost heave pressure model have been obtained, two factors have been often ignored, which are in-situ stress and freeze-thaw cycles. Therefore, the calculation mechanical model of coldregion tunnels is established and the expression of frost heaving pressure considering frost heaving effect and in-situ stress is derived based on the elastic theory. The relationship between the elastic modulus of surrounding rocks and the number of freeze-thaw cycles was fitted by experimental data and the calculation formula of frost heaving rate of rocks considering their porosity change caused by freeze-thaw cycles is derived. Based on that, the calculation method of frost heaving pressure considering in-situ stress and freeze-thaw cycles is proposed. The example analysis results show that frost heaving ratio and frost heaving pressure gradually increase with freeze-thaw cycles, which are eventually subjected to a steady value. Simultaneously, the frost heaving pressure acting on lining increases with in-situ stress for tunnels in cold regions and some effective insulation measures should be applied to prevent frost damage. KEYWORDS: Frost heaving pressure, Cold-region tunnels, Freeze-thaw cycles, Analytical solution, Zero-frost heave displacemen

A fully coupled thermo-mechanical peridynamic model for cracking analysis of frozen rocks

In cold regions, the crack propagation and coalescence behaviors of frozen rocks with ice-filled flaws are very complex. Research on the failure mechanisms of such rock masses is essential to ensure the structural safety of geological engineering in low-temperature environments. Therefore, a fully coupled thermo-mechanical model considering the frost heave effect was constructed using the ordinary state-based peridynamic (OSBPD) theory, and the cracking characteristics of frozen rocks were analyzed. The constitutive equations of the OSBPD model were modified by introducing the coupling term for the thermal-structural interaction and an equivalent pressure density term for frost heave. An improved global convergence criterion was also proposed to achieve a fast convergence to the numerical solution. The correctness and validity of the proposed coupling model were confirmed using several numerical examples. Additionally, the effect of frost heave pressure on the cracking behavior and mechanical properties of frozen rocks was thoroughly discussed. The results show that (a) the frost heave pressure drives the rock to crack along the direction of prefabricated flaws, and (b) the ultimate compressive strength of frozen rocks exhibits a decreasing trend with an increase in frost heave pressure.

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.

Characterizing frost heave pressure distribution on rock crack surfaces during freeze–thaw

Frost heave pressure plays a pivotal role in driving the occurrence and expansion of rock cracks. Thus, understanding the distribution and evolution of frost heave pressure on rock crack surfaces is integral to elucidate the mechanism of rock mass damage caused by freeze-thaw. In this study, a unique frost heave pressure monitoring experiment was performed, employing a membrane pressure sensor to provide real-time monitoring of frost heave pressure distribution across an entire rock crack surface. Simultaneously, temperature changes within the crack during freeze-thaw were monitored. Various factors including freezing temperature, crack water content, and lithology, were analyzed for their influence on the frost heave pressure distribution on the crack surface. Findings indicate that the frost heave pressure evolution during freeze–thaw can be divided into five stages: incubation, eruption, fall, equilibrium, and dissipation. The frost heave pressure is not uniformly distributed across the rock crack surfaces, with 0 MPa pressure on the upper part of the crack. The distribution pattern of frost heave pressure on the crack surface features smaller edges surrounding a larger middle area. No obvious correlation is observed between the maximum frost heave pressure and the freezing temperature. However, as the freezing temperature decreases, the maximum pressure-bearing area on the rock crack surface gradually increases. Additionally, as the water content within the crack decreases, there is a noticeable decrease in the distribution of frost heave pressure on the rock crack surface. Regarding frost heave pressure monitoring tests under four different lithological conditions, crack expansion was observed in fine sandstone, granite, and limestone specimens, but not in coarse sandstone specimens. The findings from this research enrich our understanding of the incubation mechanism of rock mass freeze–thaw disasters in cold regions, and serve as a reference for calculations and numerical simulations of rock crack frost heave pressure in these areas.

Cyclic freezing-thawing induced rock strength degradation, crack evolution, heave and settlement accounted for by a DEM model

A general discrete element method-based model is proposed to investigate the cyclic freezing-thawing induced damage of fractured rocks. A set of cracks is defined as an assembly of interparticle pores that are interconnected due to self-definition (pre-existing) or contact breaking (external force induced). During the freezing-thawing simulation, only the rock grains surrounding the cracks are subjected to frost heave pressure, which are expected to cause contact breaking and crack propagation. In this sense, most of the pores that do not form cracks in the numerical model will not participate in the calculation, so the computational cost and time are substantially reduced. The cracks connected to the atmosphere, i.e. the model boundaries, are classified as inactive cracks and their frost heave pressures are removed accordingly. Therefore, model convergence is recognized when all cracks are converted to inactive. Parametric analysis is further performed to show the influence of some important input parameters, including the unfrozen water content, calibration factor of frost heave pressure, crack density and dip. Finally, the freezing-thawing damage of rocks is quantified by the reduction in uniaxial compressive strength after a prescribed number of freezing-thawing cycles. The results are validated with an analytical solution. It is shown that the rock strength degradation, crack evolution, heave and settlement can be well simulated by the proposed model. This methodology can be extended to large-scale problems such as glacier slope instability or landslides.

A method of safety monitoring and measurement of overall frost heaving pressure of tunnel in seasonal frozen area

Abstract Antifreeze design, scientific operation, and maintenance of tunnels with broken surrounding rock in seasonal frozen areas are key factors that affect the safety of tunnel. According to a freezing damage treatment project, theoretical analysis, field monitoring, and numerical simulation are used to study the calculation method of the overall frost-heaving pressure of a tunnel with broken surrounding rock in the seasonal frozen area. Based on the overall frost-heaving model of the broken freeze–thawing lithosphere, a calculation method of the overall frost-heaving pressure of the horseshoe-shaped tunnel with broken surrounding rock in a seasonal frozen area is proposed. The results show that the management grading results based on the freezing depth of the surrounding rock on site are consistent with those based on the minimum safety factor of the lining structure, which indicates that the proposed method for calculating the overall frost-heaving pressure of broken surrounding rock tunnel and management standards for safety monitoring and measurement of tunnel linings can be applied to engineering practice. The research results can provide a reference for the calculation of frost-heaving pressure, operational safety, and prevention of freezing damages in tunnels with broken surrounding rock in a seasonal frozen area.

The mechanics of frost heave with stratigraphic microstructure evolution

Frost heave is a major cause of engineering geology hazards in cold regions, which is mainly the result of frost-heaving pressure due to the non-linear transport-freezing of water in the pore network. However, few studies have fully quantified the contribution of the strata pore-network structure to that pressure and the hazard to cold-region projects under multifactorial effects. Therefore, to address this long-term challenge in cold regions, we pioneered a generic, interdisciplinary, thermal-hydrological-mechanical fractal model for the quantitative study of the effect of strata microstructure on frost heave and hence the assessment of construction risk for engineering geology projects. First, a strata frost heave model based on fractal theory is proposed, with pore fractal dimension, maximum pore diameter, and pore tortuosity fractal dimension used to characterize strata pore density, pore size, and throat complexity, respectively. Secondly, the numerical model is compared with field observations in cold-region projects, and reasonable agreements can be obtained. The results indicate that various fractal parameters have different effects on engineering geology projects in cold regions. The strata displacement changes by 9.7–20.3% as microscopic parameters change. This study contributes to a better understanding of the micro- and macro-interactions of soil in cold regions, as well as a reference for geoengineering stability in cold regions under frost heave conditions.

Study on the evolution and dominant mechanism of frost heave pressure in the fracture of rock masses

Study on the evolution and dominant mechanism of frost heave pressure in the fracture of rock masses

Peridynamic investigation on crack propagation mechanism of rock mass during excavation of tunnel group in cold regions

An extended ordinary state-based peridynamic model was developed to investigate the crack propagation of surrounding rock due to tunnel excavation. The frost heave effect on the crack surface was described by an equivalent pressure density. Two numerical examples were conducted to verify the effectiveness and robustness of the proposed model. Moreover, the influence of frost heave pressure, buried depth and rock elastic modulus on damage characteristics of the surrounding rock was investigated. The results demonstrate that massive microcrack damage will be formed at the invert when the tunnel is excavated in a deeply buried rock mass or soft rock stratum. HIGHLIGHTS A peridynamic model of rock mass under excavation and frost heave was constructed. Damage characteristics of surrounding rock could be simulated efficiently. Frost heave load was exerted on the crack surface by an equivalent pressure density. The effects of frost heave load, buried depth and rock elastic modulus were studied.

Model test and numerical simulation of foundation pit constructions using the combined artificial ground freezing method

With the increasing demand for water resources protection, realizing undrained excavations in foundation pit engineering has become a crucial technical problem to be urgently solved. In this study, we proposed a new design concept—the combined artificial ground freezing method. This method uses the diaphragm wall as the vertical support and the frozen curtain generated by freezing pipes in a temporary shaft as horizontal support. A model test and numerical simulation were performed to analyze the evolution law of the temperature field and the interaction mechanism between the freezing process and the diaphragm wall. The above research results show that the combined artificial ground freezing method could effectively and inexpensively seal the foundation pit. During the freezing period, the frost heave pressure on the contact surface of the frozen curtain and diaphragm wall was 30– 60 kPa and 25– 35 kPa in numerical simulation, much lower than the diaphragm wall's critical design value. Therefore, frost heave would not damage the diaphragm wall. In the end, the design criterion of the freezing pipes deflection form was proposed. The study provided a reference for designing and constructing foundation pits using the combined artificial ground freezing method.

Frost Heaving and Induced Pressure of Unsaturated Interfacial Zone between Gravel Ballast and Subgrade

Most existing railroads are composed of gravel ballast. One of the major issues with gravel ballast is frost damage in cold regions. Gravelly soils are known to be not prone to frost action due to their low water retention capacity and high hydraulic conductivity. However, reports indicated continued frost damages resulting from the mixed zone between gravel ballast and subgrade. This study evaluated the frost heaving and induced pressure of gravel ballast–subgrade soil mixtures via 1D soil column testing in a cold chamber. Gravel ballast and subgrade soil were collected from the railroad in situ. Various mixing ratios and degrees of saturation were used as factors affecting the frost experiments. The mixtures were placed in the cold chamber, and vertical displacements and pressures were measured. Overall evaluations showed that gravelly soils are not a geomaterial prone to frost damage; however, the frost potential of gravel ballast increases as the degree of saturation and the mixing portion of the subgrade soil increase. Therefore, the interfacial zone between gravel ballast and subgrade soil, especially where possible mixing with low drainage exists, needs cautions of potential frost damage.

Evolution Patterns of Frost-Heaving Pressure with Partial Ponding in Cold Region Tunnels

The calculation of the frost-heaving pressure is one of the key issues in the frost-resistant design of tunnels in cold regions. To reveal the frost heave mechanism of partial ponding behind the tunnel linings, a three-dimensional geo-mechanical model test was developed that only considered the frost heave load. A self-designed water bladder equipment was set up to simulate the partial ponding. The frost heave response characteristics of the surrounding rock with partial ponding were simulated to analyze the change law of temperature field and frost-heaving pressure under freezing by using air-conditioning to reduce the ambient temperature of the model test. The changes in the internal temperature of the surrounding rock and the evolution of the frost-heaving pressure over time under different thicknesses of partial ponding and different levels of surrounding rock were compared. The theoretical calculation value of frost-heaving pressure and the test values of the model test were compared and analyzed using the numerical simulation method. The results showed that the temperature of the surrounding rock presented three-stage changes, which showed a lagging characteristic relative to the environmental temperature. The empirical equation for the relationship between the frost-heaving pressure and time was obtained by nonlinear fitting of the experimental results. Taking advantage of the regular tetrahedron calculation model, the paper established a semiempirical frost-heaving pressure model considering time and space effects, which was identical with the frost-heaving phenomenon from the experiments. Theoretical analysis, experiments, and numerical simulation show that the frost-heaving pressure increased along with the depth of partial ponding and the elastic resistance coefficient of surrounding rock, which could provide references for revealing the frost-heaving pressure of partial ponding behind tunnels of cold regions and has a significant meaning in the engineering application.