Journal of Cold Regions Engineering

Snow and ice on roads often lead to increased rolling resistance that makes roads less accessible and less attractive for cyclists. Introducing a minimum requirement for rolling resistance in winter maintenance of cycleways may increase the attractiveness of winter cycling. To control the rolling resistance level, an objective measurement method is needed. This article presents a new method for measuring rolling resistance for cyclists by using an instrumented bicycle. The new method utilizes measurements of pedaling power and resistive forces from gravitation, acceleration, and air drag to estimate the rolling resistance. Test results show that the method can measure the coefficient of rolling resistance, C_rr, with a precision, represented as the standard error of the mean, between ±0.005 (1 Hz, n = 9) and ±0.001 (1 Hz, n = 220). The accuracy of the method was verified in a test with known rolling resistance and the results yielded a mean accuracy of 96.5%.

In cold regions, the freeze–thaw (FT) cycle is a common natural physical process. It directly affects the stability of the project by changing the mechanical properties of the saline soil. Due to the presence of salt, the effect of the freeze–thaw cycle is greater, and the effects of different salts are not the same. In recent years, the construction of various projects such as ditches and roadbeds has been carried out in saline soil areas. Therefore, to study the mechanical properties of saline soil with different salt types and contents subjected to FT conditions in cold regions, in this study, saline soil from a representative site in Nong’an was selected for the preparation of artificial specimens considering different salt types (Na₂SO₄, NaHCO₃/Na₂SO₄, and NaHCO₃), salt contents (0%, 0.5%, 1%, 2%, and 3%), numbers of freeze–thaw cycles (0, 10, 30, and 60), and confining pressures (100, 200, and 300 kPa); unconsolidated–undrained (UU) triaxial compression tests were carried out to study the mechanical properties including the stress–strain relationship, peak undrained shear strength (τ_u), cohesion (c_u), and internal friction angle (φ_u). The results showed that the stress–strain relationship, τ_u and c_u, basically showed a steady decline with an increase in the number freeze–thaw cycles under the condition of the same salt type and salt content, and the dynamic evolution of the soil structure was the main reason for this change. Using the Gouy–Chapman diffusion double-layer theory, the influence mechanism of the salt content on c_u and φ_u under different numbers of freeze–thaw cycles was analyzed. There was a threshold salt content (approximately 2%) by analyzing the change law of τ_u and φ_u, and the values of different salt types were different, but the difference was not large. By comparing the properties of Na₂SO₄ and NaHCO₃, the mechanical properties including the stress–strain relationship, τ_u, c_u, and φ_u, were analyzed, and it was confirmed that the effect of Na₂SO₄ on the soil was greater than that of NaHCO₃. According to the relationship between the change law of τ_u and the change law of c_u and φ_u, it was found that the freeze–thaw cycle mainly affects τ_u by affecting c_u, and the salt content mainly affects τ_u by φ_u. For different salt types, the freeze–thaw cycle effects and salt content are different, which in turn affects τ_u. Finally, the gray correlation degree was used to analyze the influence of each factor on the strength, and the order of influence of each factor on the strength was determined as the confining pressure > freeze–thaw cycle > salt type > salt content.

The repeated passage of ships through ice-infested waters create a field of broken ice pieces. The typical size of the broken ice pieces is generally <2.0 m. This area might be referred to as a brash ice field. The movement of ships and vessels leads to the transportation and accumulation of broken ice pieces in a brash ice field. A better understanding of the properties and behavior of brash ice could improve the estimates of ice load that are associated with shipping in a brash ice field. An in situ test referred to in this study as a pull up test will be performed in Luleå harbor, Luleå, Sweden. An attempt will be made to estimate the mechanical and physical properties of a brash ice field based on the in situ test results. The test setup, procedure, and test results will be described in detail. Furthermore, the test will be simulated using the smoothed particle hydrodynamics (SPH) formulation. The numerical simulations will calibrate the numerical and material model of brash ice using the pull up test measurements. In this numerical model, a discrete mass-spring-dashpot model will be used to simulate buoyancy and drag. The continuous surface cap model (CSCM) will be used as a material model for the brash ice. The elastic modulus and the fracture energy of brash ice as a material model input will be estimated by an ad hoc scaling formula. The parameters, such as void fraction (V_f), cohesion (c), and angle of internal friction (φ) will be altered to assess their influence on the test data. The analysis of the in situ test results and the simulation results provide a preliminary approach to understand the brash ice failure process that could be further developed into modeling techniques for marine design and operations.

Frost jacking of electricity transmission tower (ETT) pile foundations in permafrost regions of the Qinghai–Tibet Plateau is becoming increasingly serious. This study investigated the effects of thermosyphons on the frost jacking characteristics of such pile foundations. Field tests of pile foundations with and without thermosyphons were carried out in the Wonkhu–Budongquan section of the Qinghai–Tibet Plateau. A three-dimensional finite-element model was established to analyze the effectiveness of thermosyphons, ground temperature distributions, and jacking displacements and force characteristics of ETT pile foundations. The results showed that the power of thermosyphons decreases yearly within 30 years. The thermosyphons can effectively increase the cold reserves of the permafrost and reduce the soil temperature; the soil temperature around the pile and the depth of thaw is the lowest in the fifth year, and this will increase the top of permafrost by 48 cm in the thirtieth year. Thermosyphons can effectively increase the adfreezing force of the pile side below the active layer and reduce the frost jacking displacement, thus alleviating frost jacking damage to ETT pile foundations.

Highway agencies use significant financial resources to operate traffic monitoring programs. Conventional traffic monitoring practices are operated only during weather-permissible periods, leading to inefficient traffic monitoring caused by restricted sample sizes. None of the previous studies considered the possibility of executing a traffic monitoring program throughout the entire year including wsevere winter weather conditions. The objective of this research was to diagnose the influence of snowfall and temperature on traffic volume changes according to vehicle class by employing two phases of statistical approaches and to propose unique traffic investigation programs for a different type of vehicle. This research used huge vehicular records archived for 6 years at the weigh-in-motion site operated in Leduc City, Alberta, Canada. Three vehicle classes classified from the raw data were used in the analysis. Three classes were total traffic, passenger cars, and truck traffic. Both layers of the statistical approach reported that passenger vehicles are impacted by climate elements. However, the truck was not significantly affected by snowfall and temperature. The results of this investigation will support highway agencies in developing evidence-based programs for traffic counting and road maintenance in winter.

Radial stress produced by the freezing of soil mainly results from two parts: the segregated ice lens and the in situ freezing of pore water. However, most studies concentrate on the stress of freezing direction, but little known about radial stress. In this study, a series of freezing experiments were conducted by a novel designed frost heave cell, which can provide strong radial constraint to reduce the possible uneven deformation in the radial direction. To distinguish the contribution of in situ freezing from segregated ice lenses to the radial stress, the authors adopted three different non-frost-susceptible materials (Toyoura standard sand, washed sand, and 0.1 mm glass beads) and agar as the experimental samples. Next, the authors compared the radial stresses produced by the freezing experiments of these four different materials with that of frost-susceptible material. In order to clarify the influence of unfrozen water content on radial stress, the authors adopted an improved pulse nuclear magnetic resonance method to measure the unfrozen water content at negative temperatures for these four different materials. In comparison with other research concerning the freezing stress of sand, it is concluded that in situ freezing of non-frost-susceptible materials produces isotropic stress in freezing and its radial direction. The sizes and surface conditions of particles are considered as the main factors that affect the maximum value of radial stress. The reduction process of unfrozen water affects the increasing curve of the radial stress of agar during freezing.

The durability of structures is greatly affected by their level of exposure to environmental and climatic conditions. In the case of northern structures, a major factor of deterioration is the corrosion of reinforcing steel due to the ingress of chloride ions from deicing salts during the winter season. The rate of penetration of chloride ions is a function of the properties of the concrete and exposure conditions, which can be direct (e.g., ponding on a slab), by splashing (e.g., on parapets), and by mist. Several models have been proposed to model the ingress of chloride ions for each mode of exposure; however, many assumptions are required for boundary conditions at the surface of concrete elements given the current state of knowledge. The objective of this research is to address these issues through the development of a custom meteorological station and measuring devices that can be deployed near existing structures. In this article, the station and its measuring devices are described, and typical data collected for one winter season are described.

Helical steel piles (HSPs) are currently used as supports for photovoltaic panels in seasonally frozen ground in order to mitigate the adverse impacts of frost jacking; nevertheless, issues frequently arise due to considerable frost-heave forces through the frozen domain and the piles' limited embedment depth. This study aims to properly estimate the heaving of HSPs and the mobilized resisting forces as the frost penetrates, providing a quick guide to the application. To this end, small-scale model tests were first performed on three types of HSPs installed in cohesive soil with a straight-shaft pile served as a comparison. The pile head was vertically constrained or unconstrained when the surrounding soil was to be frozen from the top down. A linear relationship between the anchor-resisting force and pile head displacement was then derived from test data, and its implications for other boundary conditions (e.g., dead load and flexible boundary at pile head) were discussed. A calculation method was finally proposed to analyze the thermomechanical behavior of HSPs during unidirectional freezing process. The applicability of this approach was examined by two indicators. Hopefully, the findings of this paper can be synthesized into design criterion and facilitate a wider use of HSPs.

Extensive frost heave problems deriving from 2D freezing occurred behind retaining structures. A novel test apparatus was thus developed to observe frost heave behaviors governed by 2D growth of an ice lens. The results obtained showed that the moving characteristics of the freezing front, the frost heave process, and the change of water distribution were similar with that found in 1D freezing. However, the ice lens-dependent frost heave in 2D freezing accounted for less than 75% of that in 1D freezing due to the strong interactions between the frozen zone, the unfrozen zone, and the neighboring constraints. The geometry of an ice lens in 2D freezing within soil specimen was an arc. The relationship between geometry of ice lens and its location coordinate satisfied a parabolic function. The growth rate of ice lens perpendicular to thermal gradient was usually restrained in 1D freezing, whereas it made up nearly 100% of that parallel to thermal gradient in 2D freezing. The observations on anisotropic growth of ice lens in 2D freezing have significances to develop a frost heave model for coupled heat and mass transfer.