Cold Regions Engineering 2024: Sustainable and Resilient Engineering Solutions for Changing Cold Regions

Frost effects, such as frost heave and thaw weakening, can significantly degrade pavements. Effective mitigation relies on accurate prediction of frost penetration depth. Current prediction methods use empirical equations or finite element analysis, with recent progress using machine learning. One potentially appropriate machine learning model may be a recurrent neural network, which takes in present data as input and outputs an estimation of future data, which can then be fed back into the model recursively to make further predictions. Using this method and training data from Hill Air Force Base, Utah, and Air Force Academy, Colorado, we were able to forecast soil parameters including temperature, thermal conductivity, and moisture content for frost susceptible soils, with a deviation from experimental values of no more than 10%, with the most significant contributions to accuracy being the use of gated recurrent unit neurons and the incorporation of multiple soil parameters.

In the challenging domain of engineering, where cold regions present formidable challenges, we confront the relentless forces of nature. From sub-zero temperatures to the unpredictable dance of snowfall and the silent buildup of ice, these regions demand innovative solutions to fortify the resilience of critical infrastructure. This initiative harnesses the potential of cutting-edge technology and leverages the extensive historical weather data tapestry. It introduces a pioneering strategy by integrating machine learning algorithms with extensive weather data, steering cold region engineering into an era defined by foresight and adaptability. This paper studies a transformative approach designed to forecast, prevent, and ultimately enhance infrastructure resilience in the face of rigid cold. Addressing the distinct challenges of cold region engineering, arising from harsh winter conditions such as extreme cold temperature, snowfall, and ice accumulation, we offer a comprehensive study using machine learning algorithms applied to historical weather data to construct a deeper analysis model capable of highlighting adverse weather effects. This, in turn, covers the way for optimized resource allocation, streamlined maintenance planning, and design enhancements. Our proposed study follows a systematic process, encompassing meticulous data collection, appropriate feature selection, and aiming seamless integration of the model into existing infrastructure management systems. Additionally, it facilitates the implementation of efficient and proactive measures to mitigate the impact of severe weather conditions on infrastructure. The paper also conducts three different hypotheses testing: temperature impact hypothesis, precipitation influence hypothesis, and ice accumulation and infrastructure resilience hypothesis, propelling engineering practices to new heights, particularly in the face of challenging cold environments.

Coastal erosion in the Arctic occurs due to both thermal and mechanical processes. On the Alaska Beaufort Sea coast and on much of the Chukchi Sea coast, the dominant coastal erosion mechanism is bluff face thaw/slump or thermal denudation. This erosion mechanism is a two-step process. In the first step, the bluff face thaws due to multiple heat fluxes and then slumps to the beach face. In the second step, storm surge events with their aggressive waves transport material offshore. This two-step sequence is repeated multiple times during the open water period. In this paper, using data from both Foggy Island Bay on the Alaska Beaufort Sea, we develop a process-based model of bluff face thaw/slump erosion and validate calculations with observations. Secondly, using the same model, we explore and integrate thermal and mechanical approaches to slowing coastal erosion.

The current approach to calculate ice design forces on coastal structural elements is to apply the crushing strength of thick sea ice over the width of the structural element, plus the width of any accreted ice bonded to the element. To evaluate the accuracy of this method, accreted ice samples from the Port of Alaska were harvested and tested for shear and compression strength. The resulting data were then used to calibrate a preliminary finite-element (FE) material model in Abaqus CAE 2022 using a concrete damaged plasticity model. Three simulations were created and evaluated: a uniaxial compression model of a cylindrical sample to verify the material model against the experimental results; a bare pile and ice floe interaction model; and an interaction model consisting of a vertical pile, accreted ice, and ice floe. Model results showed the modeled ice floes were extremely stiff, causing excessively large ice forces that greatly exceeded the design capacity of the pile. The model provided valuable insight into the complexities of numerical modeling of ice–ice–structure interaction and demonstrated that more sophisticated ice material models are needed for the ice floe.

In this paper, we focus on investigating ship activities in the United States’ Arctic waters and developing new viscoelastic materials that can mimic specific ice behavior. This is a significant challenge, and we discuss potential positive outcomes and how the acquired knowledge can contribute to understanding ice behavior in Arctic and Sub-Arctic regions. We first define ice and ship statistics, providing a foundational understanding of potential ice–ship interactions. We then describe the development of thought experiments for wave–ice interactions and the creation of a numerical environment for modeling purposes. This step is crucial for simulating various scenarios related to ice and wave dynamics, ultimately contributing to the design of ships capable of navigating safely in diverse Arctic conditions. Finally, stakeholder and community engagement is addressed, recognizing the importance of involving local perspectives and insights to ensure practical, socially responsible, and effective solutions.

With the global warming, the permafrost on the Qinghai–Tibetan Plateau (QTP) is degrading significantly, which brings potential threats to the major engineering projects built in or on it, e.g., the Qinghai–Tibet Highway, Qinghai–Tibet Railway, and Xinjiang–Tibet Highway. This study uses advanced survey and statistical methods to reveal the spatial distribution characteristics, development patterns, influencing factors, and formation mechanisms of the damages on the pavement induced by permafrost thawing and freeze–thaw cycles to identify their development process, evolution patterns, and different types of underlying permafrost. This will provide suggestions and guidance to the relevant departments in the decision-making, planning, design, and construction and maintenance of the running or future engineering projects on the QTP.

With global warming, engineering measures based on permafrost protection are still challenging to inhibit high ice-content permafrost thawing and subsidence in some areas of the Qinghai–Tibetan Plateau (QTP). Hence, early permafrost thawing is an effective method to reduce the later settlement of the upper infrastructure. In this study, thawing tests were carried out on permafrost using steam and heater tubes in the laboratory and on-site, respectively. The results show that steam can rapidly melt frozen soil within a radius of 5 cm, and it took 4 and 12 h to completely melt 0.09 m³ of frozen soil with 20% and 40% ice content, respectively. After thawing, the water content of frozen soil with 20% and 40% ice content at a distance of 5 cm from the steam diffusion tube was 1.68 and 1.37 times the design ice content, respectively. In contrast, the water content of frozen soil exceeding 15 cm was approximately equal to the design ice content after complete melting. The cone penetration test can be used to evaluate the melting range of permafrost. The high-power heating tube designed in this study can thaw high ice-content permafrost with the radius of at least 20 and 35 cm, respectively, within 2 and 4.5 h, and the melting rate along the depth direction was lower than that in the radial direction.

Water sealing of shafts and repair of subway tunnels all use liquid nitrogen for rapid freezing to realize emergency rescue, due to the unfrozen water content in the soil at extremely low temperatures will significantly affect the rescue project safety, therefore, it is necessary to quantitatively study unfrozen water content in soil at extremely low temperature. In this paper, based on LF-NMR, the unfrozen water content of the muddy clay at extremely low temperatures was measured, and the three cutoff values of the four types of unfrozen water in artificially frozen were quantified. The surface relaxivity value of muddy clay was obtained for the first time by combining with the MIP test. Results show that the three T₂ cutoff values for the classification of strongly bound water, weakly bound water, capillary water, and bulk water are 0.13, 0.56, and 2.58 ms, respectively, and the freezing characteristic curve of clay at extremely low temperatures can be divided into the rapid decline stage and the slow decline stage. The value of surface relaxivity of the muddy clay is 12 nm/ms. This study facilitates the stability analysis of artificially frozen projects by investigating the unfrozen water content of the soil under extremely low-temperature conditions.

In Shanghai, artificial ground freezing (AGF) method is widely used in complex engineering projects like the construction adjacent to subway tunnels. And to reduce frost heave and thaw settlement and reinforce the soil, cement will be used together. In this case, the cemented soil–concrete interface will be formed around the underground structures. Because material properties on both sides of the interface are different and the interface is one of the weak parts, it is necessary to study the shear characteristics of the cemented soil–concrete interface after artificial freeze–thaw under the influence of surrounding vibration load in underground construction for the stability of the whole structure. In this paper, large-scale interface shear tests under vibration loading were carried out, and the effect of curing time and artificial freeze–thaw on interface shear characteristics was studied. At the same time, microstructure of the cemented soil was observed by scanning electron microscope (SEM) tests. The results show that the shear strength of the interface increases with the increase of curing time. The artificial freeze–thaw has a reduction on the shear strength of the interface with vibration loading. Microscopically, artificial freeze–thaw will increase pores and produce some tiny cracks. The results in this paper provide help for further research on the shear characteristics of the cemented soil–concrete interface.

The Rammsonde is a kind of convenient, popular, and classic test equipment for in situ snow strength determination without snow sampling. While existing research has yielded empirical relationships linking Rammsonde hardness to various snow mechanical parameters, these relationships primarily rely on experimental data, necessitating a more robust numerical and theoretical underpinning. This study leverages the coupled Eulerian–Lagrangian (CEL) numerical method, recognized for its effectiveness in simulating pile-driving processes, to model the Ram penetration test on snow surfaces featuring various mechanical properties. Two loading regime assumptions are numerically investigated to simulate the impact between the dropping hammer and the Ram probe. This paper reveals the CEL approach’s capacity to offer a large deformation calculation of snow closely mirroring real-world conditions without mesh distortion. Besides the strength of snow, Young’s modulus exerts a substantial influence on penetration results and holds promise for refining future correlations between penetration outcomes and snow strength.

The bearing capacity of piles in frozen soils is a critical consideration in foundation design of cold regions. This paper presents a comprehensive study on the bearing capacity of pile foundations installed in frozen sandy soil. The research was conducted at Clarkson University, where axial loading tests were performed on model piles within a specially designed frozen soil–pile interaction lab. A soil box with dimensions of 1.38 m length, 0.9 m width, and 1.22 m height was constructed in a cold room, allowing precise temperature control ranging from −50°C to 75°C. Two steel model piles (Pile 1 and Pile 2), each with a diameter of 6.35 cm and a length of 81 cm, were installed in the soil box. To monitor strains, strain gauges were strategically placed along the surface of the piles. Notably, one of the piles was equipped with a steel angle to protect the sensors. The ultimate bearing capacity of the pile was conducted by using the ASTM D5780 quick loading test method. Throughout the tests, the temperature of the frozen soil was maintained at −4.62°C and −4.35°C for Piles 1 and 2, respectively. The results obtained from the quick loading test showed that the addition of the steel angles has increased the ultimate capacity of the pile by 26%. The load transfer analysis revealed load reduction with increasing depth into the soil.

A standard practice in seepage analyses for mining dams with frozen components is to apply homogeneous hydraulic properties, although soil is inherently heterogeneous. In this study, a basic numerical model was developed to evaluate the impact of soil heterogeneity on seepage analyses. Sixteen combinations of soil type and heterogeneity distributions at 12 sub-zero temperatures ranging from −0.1°C to −5°C were analysed. The results of the heterogeneous cases are compared to a reference case considering equivalent homogeneous conditions. The findings suggest that homogeneous cases generally underestimate seepage and preferential water flow compared to heterogeneous cases. This research is a first step in evaluating shortcomings of the current engineering practice when modelling frozen soil water flow.

Colorado State Highway 5 within the Summit Lake Park region has experienced severe roadway damage due to permafrost degradation and freeze–thaw cycling. Passing through a sensitive alpine wetland complex, current roadway configuration has yielded inadequate pavement performance, accelerated permafrost degradation, disrupted surface and subsurface water flow paths, and altered ecological processes. Roadway reconstruction utilizing an air convection embankment (ACE) was selected as the preferred design alternative to meet project priorities of permafrost and wetland restoration and improved roadway performance. A subsurface investigation was conducted, and a two-dimensional finite element model was developed to evaluate the passive cooling capabilities of the ACE and its effects on the soil temperature profile and active zone depth. Model results revealed positive mitigative effects on permafrost degradation, with diminishing cooling capabilities over time due to ongoing global climate warming. Due to the coarse, angular embankment material, and porous nature of the ACE, thaw-settlement of the roadway is anticipated to be minimized, and surface water is expected to diffuse through the embankment, contributing to restoration of the downgradient hydrologic regime. All images and illustrations within this paper are attributed to FHWA, unless marked otherwise.

Alyeska Pipeline Service Company (APSC), operator of the Trans-Alaska Pipeline System (TAPS), maintains a supporting fuel gas line (FGL) extending 148.4 mi south of Prudhoe Bay. This line, which is 10 in. nominal diameter for the first 33.9 mi and 8 in. diameter beyond that, has supplied natural gas since 1977 to three pump stations south of Pump station 1. The FGL was originally buried a minimum of 36 in. below ground surface (within the active layer of an ice-rich permafrost regime); it runs primarily along the Dalton Highway as buried piping, with two above-ground highway crossings and one elevated bridge crossing. Its route includes both thaw-stable and thaw-unstable segments, some of which have proven vulnerable to thermokarst formation. In addition, the FGL is subject to water infiltration and erosion from seasonal surface water overflow, which also can contribute to or cause loss of cover materials. Because of these dynamics, Alyeska has developed a set of monitoring methods for the FGL. These include use of in-line curvature and corrosion inspection tools, field surveys, periodic “linewalk” surveillance, and LIDAR interpretation. This paper describes these tools, as well as the maintenance approaches that Alyeska has developed over the last 46 years to maintain line stability and protection.

The Trans-Alaska Pipeline System (TAPS), designed for a peak throughput of over 2 million barrels per day, operates at an average of less than 470,000 barrels per day (2023). At peak flow, the transit time from Prudhoe Bay to the Valdez Marine Terminal was 4.3 days; it is now more than 18 days. Frictional heating is now negligible, and the extended time in transit assures significant heat loss along the line which can become operationally critical in winter months. This paper describes the development of a strategy by the pipeline operator, Alyeska Pipeline Service Company (APSC), to mitigate ice formation risks. This effort began in the mid-2000s and continues to this date. The paper details the mechanisms behind heat loss on the pipeline, the TAPS temperature gradient model, establishment of risk critical temperature thresholds, evaluation of heating methods (bulk versus slipstream), and the operation and performance of the three major “heating kits” and supplementary heating methods along TAPS. Finally, the paper will offer lessons learned to date, and how the lessons are being applied to improve future operations.

Cold regions present unique challenges for ensuring traffic safety, necessitating sustainable and resilient engineering practices. Significant hotspot crash locations and causes are the key parameters for creating an informed safety measure; however, previous studies on traffic safety have primarily focused on general factors, such as driver behavior and road conditions, without examining the relationships between incident causes and impacts. This study proposes a novel approach that uses association rule mining to analyze significant associations between traffic crash variables and evaluates spatiotemporal clustering using geographic information system tools. The findings from the spatiotemporal analysis revealed that more crashes occurred during winter, and the hotspot identification results from the Getis-Ord (Gi*) and Anselin Local Moran’s (I) statistics were compelling. The extracted association rules provide a quantitative understanding of the cause-and-effect relationships between various contributing factors. The results will help transportation planners better understand the interrelationships between the factors and their effects, enhancing traffic safety in cold regions.

In the world’s cold regions, Alaska stands as a highly seismic area with extensive permafrost coverage. Climate change has stimulated warming heightening infrastructure resilience challenges. To address these challenges, this study introduces an integrated seismic resilience framework. It employs a transdisciplinary approach, incorporating climate stressors through system dynamic models (SDM) that capture complex interactions that are difficult to be mathematically described. Furthermore, the outcome of a series of key informant interviews and an international workshop are employed to validate and expand the model. The results could lead to a policy space with two primary objectives: First, by integrating climate stressors, decision-makers can proactively consider the long-term impacts of changing environmental conditions and develop adaptive strategies to ensure infrastructure sustainability. Second, the SDM serves as a decision support tool, enabling stakeholders to understand the complex dynamics of Arctic systems and make informed choices to strengthen infrastructure resilience.

Within the Northwest Territories, Canada, permafrost is ubiquitous with communities and industrial development requiring transportation infrastructure (e.g., roadways, airports, and railways) or other linear infrastructure (e.g., pipelines and transmission lines) to accommodate potentially unstable subgrades. In these regions, transportation is of vital social, economic, and political importance. However, warming climate conditions are and will impact the integrity of existing and future transportation infrastructure constructed in permafrost regions. Existing analytical frameworks and tools for geohazard and geo-asset management have not included hazards derived from permafrost; where the ubiquity of permafrost results in the hazard being nearly ever-present underlying the infrastructure and ever changing as climate warming continues through time. This paper presents the conceptual design of quantitative risk algorithms for a geohazard assessment system using dynamic segmentation techniques to discretize the infrastructure spatially based on credibility factors for individual dangers specific to permafrost and changing thermal conditions. The hazard (probability of occurrence) will be calculated based on current conditions and projected using IPCC climate projects for the infrastructure region. This discretized approach will allow infrastructure owners to determine current high-risk areas as well as projections for high-risk areas in the future allowing for more efficient infrastructure improvement planning and an overall increase in roadway network safety.

The dynamic challenges posed by climate-driven threats indicate an acceleration in complexities surrounding the planning, construction, and maintenance of infrastructure within cold regions installations and their proximate communities. It is imperative for installations, including military posts, bases, and facilities, situated in these regions, to enhance their capacity to address the resilience of critical infrastructure while gaining a comprehensive understanding of the risks entwined with mission-critical functionalities. The proposed approach emphasizes a combined community and installation understanding of threats affecting missions through infrastructure. It seeks to identify prospective interventions geared towards risk reduction and resilience amplification. To develop a systematic assessment, we draw upon existing approaches and data on projected climate-driven hazards, incorporating interdependencies between infrastructure systems, installation capabilities, and nearby communities for our new start resilience project. This assessment focuses on a specific installation and its surrounding community infrastructure exposed to unique and compounding threats in cold regions environments. The purpose of this paper is to highlight existing tools and methodologies applicable to installation resilience assessments such as the Mission Dependency Index (MDI) and Mission Assurance Assessment (MAA), with modifications addressing not only asset management concerns but also other dependencies, including the surrounding communities in cold regions.

For current structural snow loading modeling, scale model wind tunnel tests are commonly conducted to gather bulk wind flow data across building roofs. While the wind tunnel data are reliable, collecting high-resolution data is constrained by the size of wind sensors and building geometry. This study employs computational fluid dynamics simulations, specifically using the Reynolds averaged Navier Stokes (RANS) turbulence model, to develop a cost-effective method for generating high-resolution input flow fields for RWDI’s snow loading software. A well-understood building with bluff body aerodynamics was chosen, and both a scale model wind tunnel test and a numerical model RANS simulation were conducted. The computational fluid dynamics model attains higher-resolution data than wind tunnel by directly resolving the mean flow at every grid node, correcting some post-processing artifacts. Snow-related structural loads are generally within 10% in most areas. Limitations in the computational fluid dynamics method include discrepancies in snow loads in regions with strong wind recirculation, to be addressed in future large eddy simulation computations.

To better address indoor air quality (IAQ) and mold issues in northern housing experiencing varying occupancies and indoor conditions, ventilation needs to become demand-controlled. Currently, heat/energy recovery ventilators (HRVs/ERVs) are commonly installed in northern communities and they offer constant or globally controlled airflows. Overcrowded homes are then under-ventilated, leading to higher indoor pollutants and moisture that need to be controlled. This study examines a method for providing adequate ventilation through control of ventilation based on occupancy and modulation of ventilation fans. This paper presents results from a side-by-side testing of a CO₂-based demand-controlled dual-core ERV versus conventional single-core ERV with constant flow using twin houses with simulated occupancies. The implemented strategy based on a CO₂ sensor network connected with a dual-core ERV continuously exhausting stale air from the kitchen and bathrooms was simple and efficient in adjusting ventilation rate based on occupancy rate. The potential of the CO₂-based demand-controlled dual-core ERV system was evaluated based on its capability to control indoor CO₂ levels, percentage of time kept below 1,000 ppm, and power consumption.

The occurrence of freeze–thaw cycles within the soil can result in adverse consequences such as frost heaving and a reduction in stiffness during thawing. The freezing behavior and subsequent thaw-weakening of soils can be influenced by the salt concentration in soils, which is affected due to road deicing operations during the winter. The presence of salt concentrations in soils induces a phenomenon known as freezing point depression, resulting in a decrease in the formation of ice within the soil. Concurrently, an elevated concentration of salt triggers osmotic suction as a result of the expulsion of ions towards the freezing front during the process of ice formation. These two phenomena can potentially result in either a decrease or an increase in the vulnerability of soils to frost action. The present study aims to examine the influence of varying salt concentrations on the freeze–thaw susceptibility of soil. The soil samples were treated with various salt concentrations, including 0.2%, 1%, and 5% NaCl solutions, as well as a control prepared with deionized water. The experiment involved determining the freezing point depression resulting from the presence of salt, and it was observed that the degree of depression increased in proportion to the concentration of salt. The specimens underwent a freeze–thaw test in a one-dimensional manner. During the experiment, measurements were taken for heave, temperature, and water intake. Additionally, the moisture content of the specimen was determined at various depths following the freeze–thaw test. In order to comprehend the distribution of salt within the specimen following a freeze–thaw cycle, the salt concentration of the specimens was assessed at various depths. This was achieved by measuring the electrical conductivity of pore water using a 1:5 soil-to-water extraction method. The findings indicated that the freezing point depression exerted a greater influence compared to osmotic suction, resulting in a decrease in the formation of ice within soils. The specimens treated with salt exhibited a reduction in the heave of up to 31% when compared to the control prepared with deionized water, due to lower ice segregation. Large variations in moisture content and salt concentration were observed between different specimens and along the specimen height after the freeze–thaw test. It can be concluded that freezing point depression has a greater influence over osmotic suction at above salt concentrations during freeze–thaw. Hence, the presence of salt can aid in the mitigation of freeze–thaw damage in soils.

Transportation infrastructure is of vital importance to the local communities in Nunavik, Quebec, Canada. Permafrost degradation results in infrastructure failures and affects social and economic development. The case study of airstrip embankment at Salluit was selected to help improve the understanding of ground thermal conditions in Nunavik. This paper presents the analysis of thermal data collected at the Salluit airstrip and one two-dimensional geothermal model developed to reproduce the subsurface thermal regime under the centerline of airstrip embankment. The measured embankment dimension and air temperature were used as the inputs to improve the model accuracy. Field measurement of ground temperatures for a two-year monitoring period from 2016 to 2018 was used to calibrate the model developed. This study provided valuable information to investigate the vulnerability of the airstrips using the simulation approach in response to climate warming effects in Nunavik.

In 2003, the Alaska Department of Transportation and Public Facilities began a new road building project near Fairbanks, Alaska. The project (now known as Thompson Drive) contains three different types of passive cooling systems aimed at maintaining the thermal stability of underlying permafrost. The cooling systems utilize air convection embankment layers, ventilated shoulders, and two-phase thermosyphons in three different configurations. Each of these systems provides a passive cooling effect by enhancing the winter-time cooling of the embankment and underlying foundation soils, thus helping to preserve underlying permafrost and maintain the structural integrity of the roadway. In this paper we provide a summary of the performance data for Thompson Drive over a 15-year period extending from 2005 to 2020. Each of the systems included in the project has demonstrated effective cooling of the underlying soil layers despite a string of very warm years (2014–2019) in the Fairbanks area. In the present paper we focus on the performance of Test section #1 of the project, which includes a combined system of hairpin thermosyphons and ventilated shoulders. Temperature time series for a number of key locations within the test section show the cooling progress during the test period. In addition, contour plots of mean yearly temperatures provide a spatial indication of the effectiveness of both the thermosyphon and ventilated shoulder features.

Liquefaction-induced lateral spreading can cause significant deformations and damage in structures, such as bridges, highways, and pipelines, including the broad cold regions. This paper assesses how a seasonally occurring ground crust would affect liquefaction-induced lateral spreading. One-dimensional, plane-strain analyses with shear beam boundary conditions were performed with OpenSeesPL, using the soil profile at the Slana River site and a pressure-dependent multiple yield surface constitutive model for liquefaction simulation. Four cases, including the base case (no seasonal frost) and cases with seasonal frost of 0.3, 1, or 2 m thick, were considered. The East–West motion recorded at Pump station #10 of the Trans-Alaska Pipeline System during the 2002 Denali earthquake was used as the base input. The results, including the time histories of acceleration, excess pore water pressure ratio, shear strain, and ground lateral spreading for selected depths, are presented. The results show that seasonal frost has a minor impact on the lateral spread displacement induced by liquefaction for the study site with a silty gravelly fill of relatively low permeability. Moreover, a parametric study was carried out to analyze the impact of the permeability of the fill on the triggering of liquefaction and ground surface lateral displacement. The medium sand layer almost entirely liquefies when the permeability of the fill is equal to or less than 10⁻⁵ m/s, resulting in larger lateral spreading displacements.

Unfrozen water content and thermal properties are factors in understanding permafrost degradation processes, yet there is a general lack of information on the hydro-thermal properties of relatively undisturbed ice-rich permafrost in Arctic coastal regions. In this research, we measured the unfrozen water content as a function of temperature in samples from near-surface undisturbed ice-rich permafrost using a pulsed nuclear magnetic resonance (P-NMR) testing system, in a temperature-controlled environment. We measured frozen and unfrozen thermal conductivity and heat capacity of the permafrost samples. The average frozen and unfrozen thermal conductivities are 2.23 and 1.30 W/m · K, respectively, and the average frozen and unfrozen heat capacities are 1.91 and 3.00 MJ/m³/K, respectively. To investigate the effect of salinity on unfrozen water content of permafrost, we measured the samples’ salinity levels. The salinity levels of the permafrost samples varied, ranging from 0.5 to 15.2 parts per thousand. Based on these data, we established an empirical relationship between salinity and unfrozen water content for ice-rich organic silty permafrost that can be used for engineering purposes.

Knowledge of ground ice type and volume in the upper permafrost are vital for engineering design in cold regions. Cryostructure, which describes the pattern of ice inclusions, is an indicator of the formation characteristics and geology of permafrost soil and affects the geomechanical behavior of permafrost. In this paper, we present field sampling of relatively undisturbed permafrost on the Arctic Coastal Plain near Utqiaġvik, Alaska. We characterize the cryostructure of the permafrost samples that were retrieved from five boreholes, which primarily consisted of organic silty sand with suspended ice inclusions. We conducted a series of unconfined compression tests under constant strain rate at temperatures of −2°C and −10°C to investigate the geomechanical behavior of selected permafrost cores. Here, we present the effects of temperature, dry density, water content, and cryostructure on the geomechanical behavior of ice-rich permafrost. Considering the effect of temperature, an empirical equation for short-term peak compressive strength is developed based on the experimental results. A quantitative example is provided to demonstrate how the varying geomechanical properties affect ultimate bearing capacity of shallow foundations in permafrost.

This study evaluates the freezing mechanism of pure water inside nanopores confined by cohesive soil particles using molecular dynamics (MD). The key contribution of this study is to provide an assessment to better understand the physical and chemical particle interactions among water, ice, and clay surfaces within nanopores under supercooling temperatures. The nanopores were simulated by implementing coarse-grained kaolinite surfaces face-to-face with the milliwatt water model filled in between using LAMMPS (large-scale atomic/molecular massively parallel simulator). The distance between face-to-face kaolinite sheets was controlled to target the desired nanopore size with the implementation of the piston model. The isothermal–isobaric ensemble, NPT, was used as the thermostat with hybrid Lennard–Jones and Stillinger–Weber potentials for the simulations. Simulations proceeded under freezing temperatures from 220 K (about −53°C) to 190 K (about −83°C) to capture the whole evolvement of water crystallization within clay nanopores. CHILL+ algorithm was implemented to detect ice formation and distinguish different types of ice formed within nanopores. Ovito was used as a visualization tool to monitor the progress of crystallization and a descriptive method to observe the interactions within nanopores. The results showed that both hexagonal and cubic ice were formulated almost instantaneously within the clay nanopore at the temperature of 208 K (about −65°C) with 20% more cubic ice than hexagonal ice. Some water remained liquid even as the temperature dropped to 190 K (about −83°C).

Under the influence of rainfall and groundwater, the moisture content of the roadbed in service undergoes changes, especially in seasonally frozen areas. Roadbeds in excessively wet and humid conditions are more susceptible to frost heave and settlement, thereby impacting driving safety. This study aims to investigate the water absorption and conductivity of core absorbent geotextiles under water replenishment conditions to address the challenge of increased moisture content in roadbeds. By introducing traditional geotextiles, core suction geotextiles, and no geotextiles into a sand column, with water head height and water replenishment method as variables, this study explores humidity changes at different positions within the soil column. The findings indicate that core absorbent geotextiles exhibit water absorption and conductivity capabilities, effectively influencing water content variation within a specific range.

Studies on the induced anisotropy of soil by the shear wave velocity test with bender elements have been investigated for decades, but few considered the anisotropy of soil induced by freeze–thaw cycles. This study reports the shear wave velocities of subgrade soil specimens subjected to different numbers of freeze–thaw cycles measured using bender element tests. Taking shear modulus and anisotropy index as the evaluation indicators, the evolution law of structural anisotropy of subgrade soil after different numbers of freeze–thaw cycles was systematically analyzed. The results showed that the freeze–thaw cycles can induce new structural anisotropy of subgrade soil. For the specimen with optimal moisture content which had undergone freeze–thaw cycles in a closed system, the shear modulus exhibited a slight decrease in the vertical direction and a slight increase in the horizontal direction as the number of freeze–thaw cycles increased, and the anisotropy indices were between 1.28 and 1.62. For the saturated specimen, the shear modulus exhibited a decreasing trend and eventually reached a stable state as the number of freeze–thaw cycles increased, and the anisotropy indices were between 1.1 and 1.25. The anisotropy index of the subgrade soil increased as the number of freeze–thaw cycles increased, and its growth decreased and tended to be stable after the 7th freeze–thaw cycle. The relationship between the anisotropy index of subgrade soil specimen and the number of freeze–thaw cycles could be quantitatively represented by an exponential function.

Observed and projected climate warming affects the thermal stability of airstrip foundation in Nunavik, Canada. Intensive maintenance is needed to keep a reasonable service level. The paper focus on a case study of permafrost beneath the airstrip embankment at Tasiujaq, Nunavik. Field measurements of 6 years thermal data have been used to calibrate a 2D finite element model developed to reproduce the thermal condition of airstrip foundation and simulate soil temperatures. The model developed was well calibrated to the measured temperature data, supporting the reasonable accuracy of developed model. Specific interest was paid to the side slope, where rapid permafrost degradation was expected. One adaptation solution was also proposed, based on documented thermal stabilization approach.

The nuclear magnetic resonance method (NMR) is widely used as a tool in the pore size characterization of rocks such as sandstones, carbonates, and coals. This technique also has been widely used to estimate the unfrozen water content in frozen soils; however, there are limited studies that focus on the frozen soils pore structure characterization. In the NMR tests, based on the results from the literature, a linear relationship is typically assumed between the pore size (R) and transverse relaxation time (T₂), of the transverse magnetization decay. This relationship is mathematically represented as $\frac{1}{T_2}=\frac{2{\rho }_2}{R}$, where ρ₂ is a constant representing the surface relaxivity. Traditionally, ρ₂ is determined by T₂ cutoff values, which is a relaxation time threshold that divides the T₂ spectrum into two zones: namely, the bound water and free water in frozen soils. Conventionally, centrifuge experiments are used for determining the cutoff value in the field of petroleum engineering. The key parameter ρ₂ is also approximately estimated or assumed based on the information from the published literature for different types of soils. In other words, T₂ cutoff value is based on approximations that have limitations or based on centrifuge tests that need elaborate testing which is expensive. In this paper, a new method is proposed to calculate T₂ cutoff value from the NMR test results on a saturated frozen silt clay. The key advantage of this method is that it alleviates the approximations or the use of expensive centrifuge tests for the estimation of the cutoff value, T₂. The proposed method in this paper is useful for better understanding the behavior of frozen soils with the aid of simple and inexpensive methods.

Energy shafts and energy tunnels are a kind of energy conservation and environmental protection underground structures. They can be used as shallow geothermal energy harvesting systems in cold regions. The theoretical research and practical application of energy shafts are still in the initial stage, and there are relatively few related experiments. This paper takes the Shanghai Taihe energy shaft test section in winter as the research background. It numerically analyzes the thermal-force response test of the energy shaft using COMSOL software. And compared with the Beijing Qinghuayuan energy tunnel for applicability evaluation and analysis. The results show that the heat exchange capacity of the Shanghai energy shaft is better than that of the Beijing energy tunnel due to the difference in the geological environment. Meanwhile, the temperature stress generated during heat exchange in Shanghai energy shafts is less than that in Beijing energy tunnels. Therefore, the energy underground structure is more applicable to the Shanghai strata in winter. Based on the thermal results and economic considerations, it is suggested that the inlet fluid velocity of the energy shaft is around 0.6 m/s in winter. The heat transfer tube spacing between 0.2 and 0.3 m can ensure a high heat transfer capacity.

The depth to ice-bonded permafrost is a critical piece of information for engineering design in cold regions. The use of non-invasive methods allows depth measurements to be made more rapidly than using traditional invasive methods resulting in project savings. However, while non-invasive methods may be faster than invasive techniques, non-invasive techniques must be carefully analyzed to produce meaningful results. Here we present the analysis of a unique surface wave dataset acquired in August 2023 in Eagle Summit, Alaska. Measurements followed a dynamic data acquisition methodology that resulted in multichannel analysis of surface waves (MASW) data from arrays of different lengths (23 and 2.3 m) and waveforms associated with different surface waves (i.e., Rayleigh and Love) and particle motion directions (i.e., Rayleigh-vertical, Rayleigh-inline, and Love-crossline). The Eagle Summit site (65.4621N, 145.4349W) is of particular interest because of the challenges associated with the data acquisition and interpretation. These challenges include the presence of thick near-surface organic material, obfuscating near-field effects, and ambiguous multi-mode dispersion trends. Yet, despite these challenges, the authors were successful in characterizing the shear wave velocity (Vs) to a depth of 5 m and identifying the top of ice-bonded permafrost at approximately 0.45 m. The authors hope that by presenting this unique and challenging dataset to highlight key challenges and provide recommendations for performing seismic measurements at permafrost sites.

This study investigates several of the snowpack micromechanical and microstructural properties which are critical to assessing the engineering capabilities of snow, such as stability. Snow density, compression strength, and microstructural element deflection at rupture were derived using the 2017 NASA SnowEx SnowMicroPenetrometer datasets from the Grand Mesa, Colorado, USA. Our study employs a comprehensive methodology involving spatial statistical relationships and physically based calculations to assess these microparameters. The SMP force profiles were initially pre-processed to correct signal errors and eliminate non-snow portions. Results from the statistical analyses reveal notable spatial auto- and cross-correlations among compression strength, deflection at rupture, and snow density. Despite non-uniform spacing between the sampling locations, results indicate positive cross-correlations between snow density and compression strength, as well as between snow density and deflection at rupture. Conversely, an observable negative correlation exists between compression strength and the rupture deflection.

Utilizing Sentinel-1 single look complex (SLC) products as the initial image, we employ the differential interferometric synthetic aperture radar (D-InSAR) technique to derive the most up-to-date digital elevation model (DEM) dataset of the mountainous region, located in Tianshan Mountain and Zheduoshan Mountain, China. This approach can minimize the preliminary scanning workload due to limited knowledge of the surveyed area, breaking through the limitations of conventional drone power sources, and thereby enhancing the efficiency of unmanned aerial vehicle (UAV) aerial surveys in the field. Here, we present a demonstrative experiment showcasing the method’s feasibility.

Aiming at the many shortcomings of the current traditional monitoring methods, such as high cost, inability of real-time solving, and high requirements for the monitoring environment, we propose a three-dimensional coordinate calculation method of feature points based on the close-up photogrammetry technology, and analyze and research on the calibration of the camera parameters, identification and localization of markers, and calculation of the coordinates of feature points. Firstly, the calibration method is selected for camera calibration test, and the internal and external parameters of the camera are calculated; secondly, artificial markers are selected, target detection algorithm is used to identify the markers, and the marker images are preprocessed to obtain the 2D coordinates of the feature points; lastly, the matrix transformation of the image under the spatial system is analyzed through the projective geometric transformation, and the mathematical characterization of the relationship between the 2D coordinates of feature point pixels and the actual 3D coordinates is established.

Frozen soil engineering usually involves many dynamic loads, so it is necessary to study the deformation and dynamic characteristics of frozen soil under different dynamic loads. How to simulate and realize these complex cyclic stress paths is the premise. Based on five typical cyclic stress paths, their theoretical formulas are derived in this paper. Meanwhile, the loading effect of the paths is tested by the frozen soil hollow apparatus (FHCA-300). The results show that the paths can be controlled precisely by the FHCA-300. It is hoped to provide an experimental reference for the study of frozen soil under complex cyclic stress paths.

Based on the local conditions, the causes of pavement distress in the existing bus-rapid-transit (BRT) lanes in Lanzhou, China, were analyzed and summarized. Based on the analyses of the stress–strain condition of BRT lane pavements and the conduction state of solar radiation in the pavement material structure, the forms of rutting, congested packs, and other road pavement distresses and the direct causes of the distresses were found. A comparative analysis of the status quo, rutting-resistant asphalt, changing the aggregate particle size ratio, and three working conditions concluded that the use of a horseshoe-shaped asphalt material for the surface layer is a suitable improvement option.

In order to clarify the structural characteristics and applicability of heavy-duty bus lane pavements in cold regions, this paper takes the BRT (Bus Rapid Transit System) special line in Lanzhou City as the research object and proposes three asphalt pavement structural schemes using the theory of multi-layer elastic laminated system [Scheme I (P₁): SMA-13+AC-20+AC-25; Scheme II (P₂): SMA-13+AC-20+ATB-25; Scheme III (P₃): block masonry + cement treatment layer + gravel soil], and based on HPDS2017 and GeoStudio 2018, the study is centered on its service performance (permanent deformation of pavement, road surface acceptance bending settlement value). The results show that: rutting is the main deterioration problem, and BRT lanes are more serious; the rutting resistance of P₁ is stronger than that of P₂; the design permanent deformation of P₃ is smaller than the design bending settlement value of P₁ and P₂, so the rutting deterioration resistance of block pavements is better than that of asphalt pavements. Combined with P₃, a combined scheme is proposed, i.e., P₃ pavement is paved at BRT station stops and P₁ pavement is paved at driveways.

The global phenomenon of climate change has led to significant environmental transformations, particularly affecting cold regions due to their extreme temperature dynamics. Among the critical elements facing the consequences of climate change in these regions are pavement structures, essential components of roadway, and airport infrastructure. This study explores the repercussions of climate change on pavement structures within cold regions, focusing specifically on shifts in temperature patterns and, subsequently, frost depth. Through the analysis of temperature records, this research investigates the annual average temperatures, emphasizing trends spanning multiple decades. Complementary to this, freezing degree day data are utilized to compute frost penetration depths and establish average trends over the same extended timeframe. By comparing three prominent Alaskan regions in terms of both temperature variations and frost penetration, the study aims to discern the direct implications of climate change. The regression analysis reveals noteworthy statistical changes in frost penetration depths across all studied locations. Projecting from current trends, future estimates for frost penetration indicate potential variations of around 15 cm over a 40-year period, contingent on the region. This study not only investigates if tangible effects of climate change on pavement structures exist but also offers valuable insights into potential long-term consequences for infrastructure in cold regions.

Frost heave and thaw weakening have a significant impact on the performance of pavement foundations in cold regions, leading to structural damage. Road agencies use different approaches, including seasonal load restrictions (SLR), to minimize the impact of this damage. Accurate and continuous measurement of displacements caused by frost action is crucial for agencies to assess the condition and behavior of pavement foundations. Existing methods, such as vehicle-mounted laser sensors and surveying equipment, have limitations in capturing the temporal distribution of displacement in roadways. Shape array accelerometers (SAA) can measure the ground’s displacement in real time and come with temperature sensors that provide temperature measurements at its location. This study discusses the installation procedure and evaluates the effectiveness of SAA in characterizing frost heave–thaw settlement of flexible pavements. SAA was installed along the cross-section of a flexible pavement within the Minnesota Road Research Facility (MnROAD) mainline on Westbound I-94 near Albertville, Minnesota. Minnesota falls in the wet-freeze climatic region, making it highly susceptible to freeze–thaw damage. The collected displacement and temperature dataset for the 2022–2023 freeze–thaw season was analyzed, and maximum settlement of 3.5 and 10.3 mm were observed in the shoulder and passing lane, respectively. The temperature data indicated that the ground started to settle when thermocouple readings went below freezing, suggesting ice lens formation, resulting in the contraction of the soil structure. After the spring thaw, a maximum residual settlement of 6.6 mm remained along the wheel paths, but the ground eventually stabilized once the thawing was complete. The efficacy of SAA in capturing real-time displacement data indicates its potential for broader implementation in similar climatic conditions.

The traffic load is different from the traditional vibration load in the stress path, which is manifested as the heart-shaped stress path. A series of triaxial stress path and heart-shaped stress path tests are carried out at three temperatures in this study. The permanent strain of frozen soil under traffic and triaxial stress path were analyzed. The rational curve can used to fit the permanent strain difference between traffic and triaxial stress path. The research results can provide guidance for further understanding of the permanent strain under traffic loading.

This study aims to assess the impact of microencapsulated phase change material (MPCM) on the low-temperature cracking of asphalt binders. To achieve this objective, MPCM6D with melting point of 6°C was selected. This MPCM was introduced into PG 64-22 binder at varying dosages (0%, 5%, 10%, and 20% by binder weight) using a low-shear mixer. Subsequently, the laboratory tests were conducted on prepared binders to evaluate the influence of MPCM on thermoregulation, encompassing parameters like enthalpy change, low temperature properties (creep stiffness and stress relaxation), and complex shear modulus change rate of binders. The results of the study revealed a direct correlation between the dosage of MPCM and the observed enthalpy changes. Moreover, matching of measured enthalpies with the expected values confirmed effective thermoregulation achieved during blending process, demonstrating survivability of capsules. Additionally, analysis using bending beam rheometer results indicated increase in creep stiffness and slight reduction in creep rate, depicting decrease in low-temperature cracking resistance, for MPCM modified binders. Further, it was observed from temperature sweep results that the MPCM6D exhibited the ability to enhance low-temperature cracking within the thermoregulation range. In conclusion, this study recommends exploring MPCMs with broader thermoregulation ranges or combinations of MPCM to extend their performance across wider spectrum of temperatures.

This experimental study presented the effect of cement stabilization on sulfate-rich soil from South Dakota’s Pierre Shale formation. To quantify the effects of the stabilization of sulfate-rich soils and freeze–thaw cycles, control and stabilized soil samples were prepared with cement (Type I) stabilizers (3% and 6% by weight) for a curing period of 28 days and subjected to freeze–thaw cycles in a closed system. Repeated load triaxial (RLT) tests were conducted to determine the resilient modulus of control and cement-stabilized sulfate-rich soil for a range of freeze–thaw cycles. UC strength tests were conducted to compare the compressive strength of the soil after the 1st, 4th, 8th, and 12th freeze–thaw (F–T) cycles. The trend of changes in resilient modulus was illustrated in the study. A significant decrease in compressive strength due to freeze–thaw cycles was observed. Field emissions scanning electron microscopy (FESEM) was used to demonstrate the formation of ettringite and calcium-silicate-hydrate (CSH) and determine the changes in microscopic and mineralogy due to freeze–thaw cycles.

Establishing a link between low temperature cracking resistance results for binder and mixture tests has proven challenging. This study aims to investigate the underlying factors that impact this correlation. A diverse set of loose asphalt mixture samples was collected from user agencies around North America, allowing for the extraction and recovery of asphalt binder as well as the preparation of semi-circular bend (SCB) specimens. Subsequently, extended bending beam rheometer (EBBR) and double edge notched tension (DENT) tests were conducted on the recovered binder. SCB tests were performed on asphalt mixture specimens before and after low-temperature conditioning. The analysis of correlations between binder and mixture test results revealed that considering thermo-reversible aging significantly improves the correlation between the two sets of data. Additionally, the presence of oil exudation was identified as another confounding factor for the correlation exercise.

Studded tire wear is widely considered to be a critical aspect that conditions the ride quality in cold regions. This research provides a comparative analysis of the influence of certain factors on pavement wear caused by studded tires. Abrasion resistance measurements were conducted on aggregates and asphalt specimens, using the Nordic Ball Mill apparatus and the Prall apparatus, respectively. This approach ensures an understanding of the interaction between these variables and the resultant wear response of the asphalt mixture. Tests relied on three different types of asphalt mixtures (ESG, dense-graded asphalt; EG, coarse-graded asphalt; and SMA, stone matrix asphalt), different percentages of reclaimed asphalt pavement (0%, 10%, and 20%), and different aggregate hardness. Image analysis methodology was used to assess the coarse-sectional area of the sample covered by coarse aggregates. The results showcased that harder coarse aggregates were less prone to wear. Comparisons indicate that the SMA10 yields higher abrasion resistance than the remaining mixtures used in this study. The percentage of the cross-sectional area covered by coarse aggregate influences the mixture abrasion value.

This study aims to develop a high-performance asphalt concrete (HPAC) by using waste asphaltenes to modify the binder and incorporating polyethylene terephthalate (PET) fibres to enhance the performance of asphalt mix at low temperature. As such, a method is proposed to reduce the cracking potential of HPAC mixtures composed of asphaltenes-modified binders by the addition of PET fibres. First, performance properties of a crude oil binder modified with 12% asphaltenes are evaluated by artificially short-term and long-term ageing of the binder using rolling thin-film oven (RTFO) and pressure aging vessel (PAV) procedures, respectively. Superpave binder tests are conducted on the binders through a rotational viscometer, dynamic shear rheometer, and bending beam rheometer. For modifying the HPAC mixture, 6 mm long PET fibres are used at a concentration of 0.15% where it is first tested for compactibility, reflecting field practical considerations. Then, two performance tests, namely dynamic modulus and indirect tensile strength test at low temperatures (−20°C, −10°C, and 0°C), are conducted for an effective mechanical evaluation of the mixture modifications. The results of binder performance grading tests reveal that when the base binder, with continuous PG 70.2-25.9, is modified with 12% asphaltenes, it achieves a continuous PG 82.9-21.8 with a high PG that is suitable for demanding asphalt applications. Although the addition of asphaltenes increases binder stiffness, resulting in a decrease in low-temperature grading, the overall improvement in high-temperature performance outweighs this drawback. Additionally, compactibility tests demonstrate that mixes with 0.15% PET fibres exhibit acceptable compactibility and meet the prescribed air void requirements of a maximum 6%. Furthermore, the incorporation of PET fibres in HPAC mixes increase stiffness by 63% at a 15°C and 10 Hz loading frequency, with no negative impact on the anticipated response. Compared to control mixes where no asphaltenes or fibres are used, the asphaltenes modification and PET fibre incorporation increase fracture energy by up to 27% at −10°C, indicating lower cracking potential and improved low-temperature performance. Moreover, tensile strength is enhanced by up to 18% at 0°C, demonstrating an efficient combined effect of both modifications.

Electrically conductive asphalt (ECA) pavements have emerged as a promising technology for deicing applications in cold regions. This innovative system comprises three key components: an electrically conductive asphalt layer, transverse steel electrodes, and an electrical power supply unit. The design of these components, effectively and economically, is crucial to achieving the desired deicing performance of asphalt pavements in extreme cold climates. This paper proposes a design approach for ECA pavements by determining the thermal power output required to raise and maintain the temperature of the pavement surface above the freezing point of water. Through a combination of experiments and finite element modeling, a design chart that recommends the required thermal power output for ECA pavements under ambient conditions in cold regions was developed. Based on the required thermal power output, the optimum design components of ECA pavements (thickness of the ECA layer and spacing of transverse steel electrodes) were determined.

This study explores the rheological behavior of asphalt binders under two distinct loading conditions: oscillatory shear and cyclic tension-compression. Notably, the longitudinal complex modulus of asphalt binders was found to be lower in oscillatory shear compared to cyclic tension-compression loading. Furthermore, a reduction in asphalt film thickness during tension-compression loading led to an increase in longitudinal complex modulus. Phase angle master curves of asphalt binder in tension-compression loading show rheologically complex behavior. Interestingly, alterations in asphalt film thickness had minimal influence on the phase angle master curve for tension-compression, while the phase angle master curve under oscillatory shear exhibited higher values at high frequencies or low temperatures. Additionally, the study discovered that the limiting phase angle temperature was lower in oscillatory shear than in tension-compression. A decrease in asphalt film thickness leads to an increase in the limiting phase angle temperature.

This open-ended research investigates the correlation between climate history, climate change, and pavement infrastructure performance for specific airfields in Arctic and Subarctic Alaska. Parameters such as temperature, air indices, and permafrost extent are compared to PAVER pavement management system data and construction costs for four locations. Site criteria are developed and implemented to select airfields for analysis that provide representative conditions. Climate data are analyzed to show the range of variability and temporal trends. Geotechnical borehole data are consolidated to portray nominal local permafrost extent. Data trends show that the depth of upper extent of permafrost at locations is increasing with time. PAVER family curves compare degradation rates and airfield pavements in areas with permafrost were shown to degrade two–three times faster compared to locations absent of permafrost. Regression of Pavement Condition Index (PCI) degradation rate and permafrost upper extent showed correlation. Construction cost histories from the Federal Aviation Administration Airport Improvement Program are included in trend analyses. Cost estimates for typical maintenance treatments are generated and applied to pavement inspections to model maintenance requirements and predict changes in airfield rehabilitation frequency.

The practical usage of ice has increased significantly in recent times, as it is a readily available material utilized in various applications, such as temporary constructions and permanent hydraulic structures. Consequently, there is a growing practical interest in developing models that can accurately compute the flexural strength of ice based on its compressive strength. Following the testing procedure recommended by UNI EN 196 for cement-based mortars, three-point bending, and compression tests were conducted on 40 mm × 40 mm × 160 mm ice prisms, specifically prepared under different temperature conditions. Through these tests, the ratio between flexural and compressive strengths of ice was determined. As the effect of temperature on ice is comparable with that of water/binder ratio on cement-based mortars, the flexural/compressive strength ratio of ice also depends on the frozen temperature.

This study investigates the impact of freeze–thaw (F–T) cycles on chloride ingress in concrete. Two air-entrained concretes, conventional (Group A) and fiber-reinforced (Group B), were investigated using transmission X-ray microscopy to determine the time-dependent diffusion coefficients before and after 125 F–T cycles. Performance metrics, including ultrasonic pulse velocity, surface resistivity, mass loss, and relative dynamic modulus of elasticity, were evaluated. Key findings indicated that both concretes were resistant to 125 F–T cycles, with Group A demonstrating slightly better performance. Group A showed a lower mass loss than Group B, which is consistent with the literature. Relative dynamic modulus values (99.7% for Group A and 99.3% for Group B) confirmed the improved F–T resistance. After 125 F–T cycles, diffusion coefficients remained similar, which suggests that F–T damage does not impact chloride diffusion at low numbers of F–T cycles. The findings of this study will facilitate the design of reinforced concrete structures coastal environments in cold regions with combined chloride and F–T exposure.

Mudstone mixed soil is a kind of mixed soil formed by the mixture of mudstone and surface soil. The disintegration properties of mudstone in contact with water have led to a significant decrease in the weak stability of mudstone mixed soil, so it is often treated as a kind of construction solid waste in engineering construction. In order to promote the process of resource utilization of construction waste, improve the mechanical and stability of mudstone mixed soil, and make it meet the road performance requirements of subgrade in cold areas, the benefits of the wicking geotextile were quantified via numerical simulations. The performances were compared for road embankments with and without the wicking geotextile. The results showed that wicking geotextiles can effectively reduce the moisture content of the subgrade, and the moisture content of the bottom layer of the upper road bed and the bottom layer of the lower road bed are reduced by 45.4% and 41.6%. Maximizes subgrade performance when wicking geotextiles are placed at the bottom of the roadbed. Based on research results, the mudstone soil mixture, as a solid waste, can be used as a filling material in cold regions with the application of the wicking geotextile.

Taking a loess roadbed high slope in Sanyangchuan area of Tianshui City as the study, GeoStudio software was used to conduct numerical simulation to analyze the stability of the slope under earthquake conditions, and anchor was used to strengthen the unstable slope and evaluate the reinforcement effect. The results show that when the peak acceleration is 0.25 g, the slope is unstable by using the time-history analysis method and the Newmark method. By comparing the safety factors obtained by the time-history analysis method and the pseudo-static method, we can see that the safety factor is estimated by the high average safety factor, and the minimum dynamic safety factor is the safest evaluation standard. According to the different incidence angles of bolt reinforcement, numerical simulation results show that the reinforcement effect is better when the incidence angle of bolt is 19 degrees. Meanwhile, among the three evaluation methods, M-P method may overestimate the stability of slope, and Janbu method is more conservative, while Bishop method is more reasonable.

In recent years, ultra-high-performance concrete (UHPC) has attracted interest from the research community because of its excellent physical, mechanical, and durability properties. However, due to its very high production cost, utilization of UHPC is very limited. In this context, a detailed experimental investigation was conducted to utilize locally-available fine aggregates in producing UHPCs that will help in reducing their production cost. This study reports on freeze-thaw resistance with deicing salt of the non-propriety UHPCs containing different fine aggregate and cementitious materials. Two distinct fine aggregate types, plaster sand and masonry sand, were each combined with coarser concrete sand to create a unique aggregate blend for the studied UHPCs. A total of 12 plain and fiber-reinforced UHPCs were batched using a uniform water-to-cementitious materials ratio of 0.21. The aggerate-to-cementitious materials ratio of 1.2 was kept uniform for all studied UHPCs. Due to the dense microstructure of the studied UHPCs, both masonry and plaster fine aggregates displayed similar resistance to freezing and thawing with deicing salt with mass losses ranging from +0.05% to −0.15% after 60 F–T cycles. The studied tertiary UHPCs exhibited reduced mass loss in comparison to that of the equivalent reference UHPC.

A new composite material of polyurethane-bonded rubber particle-sand mixture (PolyBRuS) is presented here. A series of cyclic triaxial tests were carried out the hysteresis curves under different confining pressures, temperatures, and freeze–thaw cycles, and then the morphological characteristics and evolution law of hysteresis curves under low-temperature conditions were analyzed. The results indicate that the dynamic strain amplitude, temperature, and number of freeze–thaw cycles have a great influence on the hysteresis curve, while the confining pressure has little influence on the hysteresis curve. While the temperature (T) is −15°C and the number of freeze–thaw cycles (N) is 25, the long-axis slope K, i.e., the elastic properties and stiffness of the PolyBRuS material, decreases with increasing dynamic strain amplitude, tends to increase with higher confinement pressures. While N = 25 and the confining pressures (σ₃) is 25 kPa, the distance between the center point of the adjacent hysteresis curve d, i.e., fine microscopic damage of the PolyBRuS material, grows with increasing dynamic strain amplitude, rises with lower temperature. While T = −10°C and σ₃ = 25 kPa, hysteresis curve area S, i.e., energy dissipation of the PolyBRuS material, increases non-linearly in relation to the dynamic strain, and reduces with the enlarge of the number of freeze–thaw cycles, however, this reduction is negligible. Further research should focus on the quantitative analysis of the morphological characteristics and evolution law of hysteresis curves.