Frost Heave In Soils Research Articles

Monitoring of changes in the thermal regime in the road structure

Freezing of wet dispersed soils is accompanied by a number of physical, physicochemical and physicomechanical phenomena and processes. In soils, when water freezes, the properties of the soils themselves change abruptly and abruptly, and the volume of frozen soil increases significantly, and not evenly. It was revealed that during freezing conditions can arise under which an increase in soil volume due to moisture migration to the freezing front and its freezing can reach tens of percent. This process is usually called frost heaving of soils. This phenomenon refers to physical and mechanical processes, as a result of which, under the influence of thermodynamic changes, the freezing soil acquires a stress-strain state. To combat frost heaving, it is necessary to study the patterns of changes in the water-thermal regime of road structures. The article presents various methods for assessing the water-thermal regime of road structures. The developed system of temperature monitoring of the road structure to a depth of up to 3 m and some measurement results are described, which make it possible to assess the temperature change at different depths from the road surface.

A study on frost heave and thaw settlement of soil subjected to cyclic freeze-thaw conditions based on hydro-thermal-mechanical coupling analysis

Frost heave and thaw settlement are the main cause for damaging the engineering structures in the region of seasonally frozen soil. The soil freeze-thaw (FT) deformation is a typical complex result of multiple physical fields and involves the process of water transfer, heat transfer, ice-water phase transition and stress redistribution. While the theory and model of frost heave have been studied for decades, less attention has been paid to the simulation for soil deformation under FT cycles. In this study, coupled equations for water, heat and the deformation of frozen soil are derived based on previous theories and are realized in numerical software. The volumetric water content of the frozen soil in the experiment was tested by nuclear magnetic resonance (NMR) technology, and the obtained data were imported into the model. Experimental soil samples were arranged in improved model equipment, and the temperature and frost heave at different heights of the soil column varied with time. The model validity and applicability based on the hydro-thermal-mechanical coupled equations is verified by comparing the results of both the experiment and numerical simulation. In this research, from the curves of the soil temperature change, water content distribution, water flux occurred at the soil bottom surface, as well as the displacement of frost heave and thaw settlement, and the pore size distribution, the characteristics of the soil subjected to cyclic FT conditions was analyzed. The existed theoretical model cannot well model the soil FT deformation. Therefore, this study may provide references for developing more accurate theoretical models on the soil subjected to FT cycles.

The Frost Heaving and Heave Properties of Soils on the Projected Moscow–Kazan Railway

The Frost Heaving and Heave Properties of Soils on the Projected Moscow–Kazan Railway

Water and salt migration mechanisms of saturated chloride clay during freeze-thaw in an open system

Water and salt migration mechanisms are of great significance for understanding the frost heave and thaw settlement of saline soils during freeze-thaw (F-T). In this study, unidirectional open-system F-T tests were conducted on saturated clay specimens with various chloride salt contents to investigate water and salt migration mechanisms. Relevant parameters, including temperature, unfrozen water content, bulk electrical conductivity, matric suction, and water intake volume, were measured continuously during testing. Besides, the water molecule mobility was obtained by the Nuclear Magnetic Resonance relaxometry tests to help understand the water and salt migration mechanisms. The test results indicated that the freezing front development was highly dependent on salt content. The matric suction gradient was found to be the driving force of water-salt migration, which was larger in specimens with lower salt content and led to more water intake. The migration of water and salt was asynchronous due to their different driving mechanisms during F-T. Specifically, salt migration was affected by both convection and diffusion, while water migration was primarily driven by convection. This phenomenon was also confirmed by the different patterns in water and salt redistributions after F-T. Meanwhile, pore water in the frozen specimens with different salinity and the same unfrozen water content was found to have the same water molecule mobility. Both the matric suction and water molecule mobility were dependent on unfrozen water content but independent on salt content. However, the salt content has a significant effect on the soil freezing point depression, which further affects the matric suction and water molecule mobility.

Frost Heave and Thawing Settlement of Frozen Soils around Concrete Piles: A Laboratory Model Test

Abstract The frost heave and thawing settlement of soils around piles could cause a series of problems, such as freezing of the pile and reduced bearing capacity of the pile. Based on the soil profiles recorded at a permafrost region in Western China, laboratory tests were performed to investigate the frost heave and thawing settlement of frozen soils around piles. The ambient temperature was adjusted in such way that the thawing and freezing of soils occurred from top to bottom, respectively. As the thawing and freezing reached different depths, the temperature, unfrozen water content, and displacements of soils around eight piles were recorded. The results showed that when the thawing was completed, the unfrozen water content of soil located at a distance equal to the pile’s diameter measured from its face was larger than that of the soil located at a distance equal to triple the pile diameters. At the end of freezing, the unfrozen water content of the soil located at a distance equal to the pile’s diameter (from the pile’s face) was smaller than that of the soil located farther (triple pile diameters). It was also shown that for the soil region between 1 and 2 times the pile diameters from its face, the amount of thawing settlement and frost heave increases, while the magnitude of the soil thawing settlement and frost heave decreases from 2 to 3 times the pile diameters. The laboratory results also showed that the difference in the frost heave and thawing settlement is related to the difference of the performance of heat transfer between the pile and soil during the freezing process. Therefore, a transverse temperature gradient exists in the pile-soil system, causing the unfrozen water to migrate toward the pile–soil interface and freeze.

A deep learning forecasting method for frost heave deformation of high-speed railway subgrade

Deformation of high-speed railway subgrades, due to low temperatures, is a common phenomenon in cold regions. In winter, the uneven frost heave of subgrade soil would cause hazards to train safety. It is therefore necessary to estimate and predict the subgrade properties. Since the variation of frost heave is non-stationary over time, traditional time series analyses have difficulties where complex physical parameters are not available. In this study, we introduce two models based on deep learning technology to predict frost heave deformation of railway subgrade. These include the artificial neural network (ANN) and long-short term memory (LSTM) network, where we used data of four sections to build the ANN and LSTM. The experimental results of the LSTM model provided lower MAE and RMSE with different datasets. The prediction of three deep deformations for the K1959 + 580 and K1962 + 618 section with slight fluctuation in the data and the performance of the ANN with MAE is 0.0090‐–0.0660 and 0.0069‐–0.0201 of the LSTM models. In the K2005 + 948 and K2029 + 829 section, ANN and LSTM estimated the frost heave deformation with MAE of 0.0061‐–0.0681 and 0.0054‐–0.0309 for a more intense fluctuation on the deformation. Our findings suggest that the network topology of the LSTM model with 12 hidden neurons performs best with fewer parameters, with an average RMSE of 0.0210 mm and MAE of 0.0138 for all the training samples, indicating that the deep learning model has high precision in this scenario.

Effect of different concrete properties on frost heave crack in U-shaped canal lining and joint

Due to seasonal frost heave of base soil, there were numerous U-shaped concrete canal linings that crack or even fracture in the irrigation area of northern China. Once the canal lining was cracked or fractured, there would lead to seepage and damage of the canal lining. This situation was adverse to water saving irrigation gravely. The U-shaped canal lining includes two parts which contain prefabricated concrete slabs and cast-in-place concrete joints. Based on the features of construction, the concrete characterization included strength and deformation had observably distinction between slab and joint of lining, which resulted the difference in frost heave effect. In this study, the cracks difference between slab and joint was quantified by the experiment of crack observation firstly. Further, the numerical simulation model with concrete damage model and smeared crack approach of frost heave force was established by the experiments of the effective frost heave and concrete mechanical properties. The crack propagation process of different concrete lining slab and joint was analyzed under the change of frost heave force. At the same time, the validity of the numerical model and approach was proven by comparing the results with the experimental. The result showed that the increase of concrete strength had a significant effect on the resistance of U-shaped canal lining to crack by frost heaving. It indicated that the tensile strength of concrete was increased by 48.28% from C15 to C20, and the frost heaving force during cracking was increased by 21.26%. The empirical equations of power function could be used to predict the cracking frost heave force of U-shaped canal lining by the concrete strength. The study provided a new idea for studying the frost heave damage process of different types of canal lining.

Experimental Study on Frost-Heaving Force Development of Tibetan Clay Subjected to One-Directional Freezing in an Open System

Frost heave of soils involves complex coupled interactions among moisture, heat, and stress, which can cause serious damage to cold regions engineering. In this paper, a series of one-directional freezing experiments were implemented for the Tibetan clay with rigid restraint in an open system. The varying characteristics of the temperature, frost-heaving force, and water replenishment during the freezing process were analyzed under different freezing temperatures (−5, −7, and − 9°C), dry densities (1.65, 1.7, and 1.75 g cm−3), and initial moisture contents (11, 14, and 17%) of the soil samples. It was concluded that the freezing of soil samples mainly occurred within 10–25 hours from the beginning of the experiment; hereafter, the soil temperatures tended to be stable. The development of frost-heaving force could be divided into three stages as slow increase, quick increase, and relative stable stages. Low freezing temperature, large dry density, and high moisture content were all the contributors to the frost-heaving process of the soil, which could increase the freezing depth, magnitude of the frost-heaving force, and amount of water replenishment. The variations in water replenishment from the open system corresponded to the three stages of the frost-heaving force but had time lags. The moisture contents at different layers of soil samples were measured after the freezing experiment. The results showed that the freeze part of soil samples experienced a significant wetting, while the unfrozen part experienced drying during the experiment. The degrees of wetting and drying were related to the freezing temperature, dry density, and initial moisture content of the soil samples. The experiment results could provide data support for theoretical study on moisture, heat, and stress coupling in freezing soil.

Evaluation of frost heave in clay soils

Frost heaving in clayey soils with a low coefficient of permeability raises a lot of questions regarding the cryosuction, surface tension forces, and accompanying phase transfer of water. The freeze-thaw laboratory test results were considered in this work in terms of temperature and volumetric parameters change, dry density, and water mass transfer. The article presents a model for calculating the mass transfer of water (vapour) in the gas state under the influence of cryogenic forces. Findings include the improved understanding of the heat and mass transfer phenomenon during the unidirectional freezing of soils in an open system. Most of the tests for engineering properties registered a slight reduction in relation to strength, cohesion, and angle of internal friction. However, there was a significant increase in the coefficient of permeability after the freeze-thaw cycles with initially dense compacted soil samples, which was due to loosening and moistening of the soil samples during the heave at sub-zero temperatures. The conceptual model for frost heave in soils was developed based on the vapour mass transfer. There was presented algorithm of vapour flow calculation in unsaturated soils using fundamental thermodynamic equations.

单向冻结黏性土水热特性冻胀试验研究

单向冻结黏性土水热特性冻胀试验研究

Study on Frost Heave Evaluation System of Large Canal Foundation Soil in Cold Area

Frost heave of canal foundation soil is the main factor of destroying canal system engineering in the cold area. Restricted by technical and economic conditions, further evaluation of the frost heaving index and system of the large channel in cold areas where needed. Based on the field investigation and relevant evaluation methods, several evaluation indexes such as water content, compaction coefficient, fine grain content, and cumulative negative surface gas temperature, the direction of canal slope are selected. Combined with the observation results of the prototype test field for many years, the frost heave degree of large channel foundation soil was comprehensively evaluated. The purpose of this paper is to standardize the evaluation method of frost heave characteristics of canal foundation soil in cold region, which has important guiding significance for the prevention and control of road frost damage in the cold region.

Research on the Temperature Field and Frost Heaving Law of Massive Freezing Engineering in Coastal Strata

In this study, based on the background of massive freezing engineering in coastal strata, the thermal physical parameters and some freezing laws of soil were obtained through soil thermal physical tests and frozen soil frost heaving tests. When the freezing temperatures were −5°C, −10°C, −15°C, and −20°C, the frost heaving rates of the soil were 0.53%, 0.95%, 1.28%, and 1.41%, and the frost heaving forces of the soil were 0.37 MPa, 0.46 MPa, 0.59 MPa, and 0.74 MPa, respectively. In the range of test conditions, the frost heaving rate and the frost heaving force of the soil increased with the decrease of the freezing temperature, and the relationship was roughly linear with the temperature. The entire cooling process could be roughly divided into three stages: active freezing stage, attenuation cooling stage, and stability stage. The range of the frozen soil expansion did not increase linearly with the decrease of the freezing temperature, and there was a limit radius for the frozen soil expansion. A three‐dimensional finite element model was established to simulate the temperature field and frost heaving of the soil under the on‐site working conditions. The entire frost heaving process could be roughly divided into two stages. The calculated temperature values and the frost heaving force values were compared with the on‐site measured values, and the results verified that the numerical calculation could accurately reflect the temperature field and frost heaving law of the formation.

An analysis of the influences of groundwater level changes on the frost heave and mechanical properties of trapezoidal channels

Abstract In this research study, platforms with different heights were established for the purpose of simulating the different groundwater level conditions. Combined with the prototype channel, the influences of the groundwater level changes on the frost heave deformations in the foundation soil and on the frost heave force of the channel, as well as on the bending moment of the channel section and water content migration of the foundation soil, were studied by the method of mechanical analysis. The research results show that, after a comparative analysis of the ground temperatures in the same layer had been completed, the difference value was found to have been less than 5%. The frost heave of the foundation soil had decreased by 0.15 cm for every 1 cm reduction in the groundwater level. In addition, the maximum frost heave force of the channel was shown to have varied with the change of groundwater level. This study's theoretical calculations determined that the most unsafe groundwater level of a typical channel was 2.61 m. It was concluded that the increase of groundwater level can reduce the amount of soil moisture transfer, while the influence of groundwater level on frost heave of foundation soil can be effectively reduced by laying polystyrene boards.

Dependence of Freezing Soil Heaving Properties on the Degree and Composition of Salinization

This research presents the experimental data on physical modeling of cryogenic heaving of saline soils under laboratory conditions in the external mass transfer and isothermal temperature mode. This paper also reports the regularities of frost heaving of sandy and clayey soils salinized with sodium chloride and sodium sulfate. The mechanism of the development of cryogenic heaving of saline soils is presented.

Полевые и лабораторные исследования действия касательных сил морозного пучения грунтов на свайные фундаменты

In conditions of heaving soil, there are tangential forces of frost heaving, which may lead to blowing out the pile foundations of above-ground oil pipeline supports. Russian design standards established the analysis and tests to determine the values of these forces. At the same time, the regulatory documents do not contain data for determining the estimated specific tangential forces of heaving acting on pile foundations of steel pipes with anti-corrosion coating. It is stipulated that for such surfaces, the values obtained in the course of laboratory or field studies shall be taken into account in analysis. The article presents the results of laboratory and field tests to determine the frost heaving forces acting on pile foundation samples made of steel pipes with and without protective coating. The data on soil temperature observations, changes in position of surface bench marks are given. Reduction factors of frost heaving tangential forces for samples with different types of coatings were found and the conclusion was made about the efficiency of the application of coatings not only for the anticorrosive protection, but also for the protection of pile from the effects of soil frost heaving.

Analysis of internal force and displacement of foundation pit pile anchor supporting structure based on soil frost heaving

In order to study the influence of soil frost heaving on the internal force and displacement of foundation pit supporting structure in seasonal frozen soil area in Northwest China, the field test of pile anchor supporting structure for deep foundation pit is carried out to monitor the change of internal force and displacement of supporting pile in winter. The interaction relationship between soil frost heaving and internal force and displacement of supporting pile is analyzed combined with temperature change conditions. The results show that: Under the condition of natural frost heaving in winter, the frost heaving effect is the most significant at 0.5 m of the upper part of the supporting pile, and the reinforcement stress value on both sides of the pile body is the largest. The change rate of bending moment of supporting pile above 3.25m is higher than that of the embedded section and the maximum bending moment is at 0.5m, while the blot has a certain constraint on the bending moment deformation. The displacement of supporting pile increases in proportion to the freezing time, and the final increase is 157.7% of the initial value. It can be seen that soil frost heaving has great influence on the internal force and deformation of the upper structure of the retaining pile. The research results can provide reference for the construction of foundation pit support engineering in similar areas in winter.

The Modelling of Freezing Process in Saturated Soil Based on the Thermal-Hydro-Mechanical Multi-Physics Field Coupling Theory

The freezing process of saturated soil is studied under the condition of water replenishment. The process of soil freezing was simulated based on the theory of the energy and mass conservation equations and the equation of mechanical equilibrium. The accuracy of the model was verified by comparison with the experimental results of soil freezing. One-side freezing of a saturated 10-cm-high soil column in an open system with different parameters was simulated, and the effects of the initial void ratio, hydraulic conductivity, and thermal conductivity of soil particles on soil frost heave, freezing depth, and ice lenses distribution during soil freezing were explored. During the freezing process, water migrates from the warm end to the frozen fringe under the actions of the temperature gradient and pore pressure. During the initial period of freezing, the frozen front quickly moves downward, the freezing depth is about 5 cm after freezing for 30 h, and the final freezing depth remains about 6 cm. The freezing depth of the soil column is affected by soil porosity and thermal conductivity, but the final freezing depth mainly depends on the temperatures of the top and lower surfaces. The frost heave is mainly related to the amount of water migration. The relationship between the amount of frost heave and the hydraulic conductivity is positively correlated, and the thickness of the stable ice lens is greatly affected by the hydraulic conductivity. With the increase of the hydraulic conductivity and initial void ratio, the formation of ice lenses in the soil become easier. With the increase of the initial void ratio and thermal conductivity of soil particles, the frost heave of the soil column also increases. With high-thermal-conductivity soil, the formation of ice lenses become difficult.

Application of PIV Technique in Model Test of Frost Heave of Unsaturated Soil

Abstract Frost heave of soil is a highly nonuniform problem, in which the local deformation is much more severe and meaningful compared with the overall deformation. When soil is upon freezing, a w...

Modelling frost heave in unsaturated coarse-grained soils

Coarse-grained soils were considered not susceptible to frost heave. However, substantial frost heave has been observed in unsaturated coarse fills in high-speed railway embankments. Recent experimental results in the literature show that vapour transfer has a considerable influence on the frost heaving of coarse-grained soil. However, vapour transfer has rarely been considered in modelling frost heave. This study presents a new frost heave model that considers vapour transfer and its contribution to ice formation. An updated computer program (PCHeave) is developed to account for the vapour transfer in unsaturated coarse-grained soils, where the rigid ice theory is applied to initiate ice lens formation in the frozen fringe. The results of the proposed model are compared with laboratory test results, which show reasonable agreement. The frost heave data monitored in 2013–2014 along the embankment of the Harbin–Dalian Passenger Dedicated Railway are also used to validate the proposed model. The prediction of the model agrees well with the measured results of frost heave and frost depth. This indicates that the proposed model can reasonably reflect the process of frost heave caused by vapour transfer in unsaturated coarse-grained soils.

Optimization analysis of heavy metal pollutants removal from fine-grained soil by freeze-thaw and washing technology

Heavy metal contaminants in clay soils can be removed through freeze–thaw cycles and washing, but the removal efficiency is low. In this study, the cause of low remediation efficiency was analyzed through the influence of eluent concentration and replenishment sequence on the frost heave of soil in combination with one-dimensional freezing soil column experiments. Results showed that the viscosity coefficient of 0.15 mol/L ethylene diamine tetraacetic acid (EDTA) increased by approximately 10% compared with that of deionized water. This condition led to an increase in the migration resistance of the eluent in the soil and a decrease in the liquid–solid ratio, which in turn decreased water absorption by approximately 62% and affected removal efficiency. The pH of the soil column increased by approximately 12.9% compared with the initial value (pH 6.93). Its value was between 7 and 8, which was within the range for conducive crop growth after freeze-thaw cycles and washing. The original structure of soil particles could be destroyed during the freeze-thaw cycles, which contributed to improving washing efficiency. After seven freeze-thaw cycles, the concentrations of the single leachate were 642.3 mg/L of lead (Pb) and 3439 mg/L of cadmium (Cd), and the extraction efficiencies were 77.24% for Pb and 37.78% for Cd. This research provids new methods that utilizes the freeze-thaw cycle phenomenon in nature for the remediation of heavy-metal-contaminated clay soils.