Understanding the thermal regime of road embankments in cold climates during winter is essential for efficient road design and accurate estimation of maintenance frequencies to reduce freeze-induced damage. In response to the challenging climate conditions in northern Sweden, an experimental field setup was designed to assess the thermal impact of culverts and accumulated snow in ditches on the thermal regime of road embankments during a winter season. This study provides detailed information on the experimental setup, highlights potential challenges from installation phase to data acquisition, and addresses measurement errors. Methods to ensure accuracy and obtain reliable data are also presented. Additionally, some of the obtained measurement results are included in this paper. The results show that snow impacts the thermal regime of the embankment from the onset of accumulation in the ditch, when the snow cover is still thin, until it reaches a depth of 65 cm. Beyond this depth, the soil beneath the snow remains almost unfrozen throughout the winter season. Additionally, the temperature distribution measurements within the embankment indicate that freezing progresses faster near the culvert compared to the rest of the embankment. However, once the culvert ends are insulated by snow cover, the frost depth in the soil near the culvert does not increase significantly, while the rest of the road continues to freeze gradually to greater depths throughout the winter season. The measurement results presented in this study provide researchers with a reliable dataset for validating numerical models in related research areas simulating cold-climate conditions. Additionally, these results enhance the understanding of the thermal regime of road embankments in typical cold climates and offer valuable insights for planning road maintenance and construction in such regions. Furthermore, this study provides essential information for researchers aiming to design and optimize experimental measurement setups in similar investigations.

Strains at the bottom of a large-scale experimental embankment dam were measured by fibre optics. The strains were measured in four sections, orthogonal to the dam axis. The fibre optic set up was operational after finalising the dam construction. The measurements were conducted continuously during the impoundment and later during the operation with an upstream water level of a maximum of 3.5 m. Based on the measurements, the post-construction behaviour of the dam was observed, indicating settlements. The foundation of the dam is inclined, which was captured by the measurements, with indications of more shear stresses developing at the downstream side. Variations of strains in the different dam zones were observed. The impoundment is causing most of the strain development in the dam. The strains develop further over time after the reservoir is at its maximum level, indicating a transient process is in place.

The appearance of ground frost is of vital importance in construction and maintenance of roads in cold climates. Frost often causes ground heave and subsequent road damage, which must be taken into account in designing the road structure. Frost depth, pavement temperature, and freezing/thawing cycles are also important for estimating the frequency of road maintenance and treatment. Various analytical, numerical, and empirical models have been developed to estimate the surface temperature of the pavement and to model the heat flow in the underlying layers. The pavement surface experiences a variety of intricate nonlinear heat transfer mechanisms during winter, making it challenging to accurately model the surface boundary. Dynamic variation of parameters such as cloud cover and traffic density during the modeling period introduces additional complexity. To address this challenge, we have established an experimental setup in Luleå, Sweden, to measure pavement profile temperatures during the winter season. Additionally, we have developed a Finite Difference Model that utilizes local weather data including dynamic cloud cover, and which also takes traffic into account. The experimental and simulation findings demonstrate how the impact of surface temperature fluctuations diminishes and, more or less, vanishes for depths more than 55 [cm] below the pavement surface. The Finite Difference Model presented in this study exhibits the ability to forecast the pavement profile temperatures, including the surface temperature based on weather conditions, with acceptable precision for at least 3 days. As a consequence, a reasonable assessment of pavement layer conditions appears feasible based on local weather conditions, and the model can serve as a useful tool for planning road maintenance and construction in cold regions.

Ground thermal regime in cold regions is influenced by seasonal snow cover, which acts as an insulating layer influencing the heat transfer between the atmosphere and the underlying soil. The thermal properties of the snow change with different environmental conditions, playing a crucial role to determine the thermal state of the sub-surface soil. Previous research in this field have faced challenges to accurately characterize thermal properties of seasonal snowpacks under varying spatial and meteorological conditions. To address this issue, two experimental field setups were constructed in Luleå, Sweden, to observe the temperature distribution of the snowpack and the ground sub-surface soil. The first experiment studied a naturally accumulated, undisturbed snowpack. The second experiment was conducted on a roadside ditch where the snowpack consists of a combination of natural accumulated snow and plowed snow from the adjacent road. In this research, heat transfer processes at both field sites were monitored over a winter season each to better understand the complex relationship between snow cover properties and sub-surface thermal regime. Furthermore, thermal conductivity of a basal layer in each snowpack was calculated over a time period, based on the field measurements. The results showed that the history of snow deposition, meteorological conditions, and changes in soil moisture impact the metamorphism process within the snowpack, thereby altering the structure of the layers of snowpack and its influence on the thermal regime of the sub-surface soil. The findings of this research have important applications in various sectors, from mining to road maintenance and agriculture.

The primary goal of this study is to evaluate the migration of fine granular materials into overlying layers under cyclic loading using a modified large-scale triaxial system as a physical model test. Samples prepared for the modified large-scale triaxial system comprised a 60 mm thick gravel layer overlying a 120 mm thick subgrade layer, which could be either tailings or railway sand. A quantitative analysis of the migration of fine granular materials was based on the mass percentage and grain size of migrated materials collected in the gravel. In addition, the cyclic characteristics, i.e., accumulated axial strain and excess pore water pressure, were evaluated. As a result, the total migration rate of the railway sand sample was found to be small. However, the total migration rate of the sample containing tailings in the subgrade layer was much higher than that of the railway sand sample. In addition, the migration analysis revealed that finer tailings particles tended to be migrated into the upper gravel layer easier than coarser tailings particles under cyclic loading. This could be involved in significant increases in excess pore water pressure at the last cycles of the physical model test.

Understanding the mechanism of excess pore water pressure generation in subgrades is essential for not only designing but also further maintenance purposes. The primary goal of this research was to investigate excess pore water pressure generation in fine granular materials under cyclic loading. A series of undrained cyclic triaxial tests were performed to study the excess pore water pressure generation in two selected fine granular materials: (1) railway sand and (2) tailings. The excess pore water pressure response of these materials was evaluated in terms of density conditions, number of cycles, and applied cyclic stress ratios (CSR). As a result, excess pore water pressure accumulated over time due to cyclic loading. However, its accumulation was significantly dependent on the governing factors, i.e., densities, CSR values, and material types. The excess pore water pressure exhibited a slight increase at low CSR values, but a sharp increase was observed at higher CSR values, which ultimately led to a failure state after a certain number of cycles. In addition, under the same loading conditions, the samples that had higher relative compaction showed better resistance to cyclic loads as compared to those with lower relative compaction. Finally, a relationship between excess pore water pressure and cyclic axial strain of the fine granular materials was discovered.

This paper outlines the design and development of a trapdoor test setup used to simulate the effect of a geosynthetic reinforcement on the load distribution in a timber piled embankment. Geosynthetic-reinforced pilesupported embankment (GRPSE) is a common foundation method for both roads and railways on soft subsoil. Timber piling allows for a solution with lower carbon footprint than concrete or steel piling. The removal of concrete pile caps further reduces the footprint but increases the requirements of the geosynthetic reinforcement. The purpose of the trapdoor test setup is to find the best suited number, placement, stiffness, and strength of the layers of geosynthetic reinforcement for different embankment heights and pile spacings. The tested embankment model consists of a vertical cross section of the embankment between two adjacent piles, assuming plane strain. The test is performed under Earth’s gravity. A hydraulically controlled trapdoor mechanism in between the two pile heads acts as the deformed subsoil. The trapdoor is composed of several segments to model a non-horizontal top surface of the displaced subsoil. Displacements are captured using optical measurement techniques to confirm and study the arch formation. The arching efficacy is quantified by pressure cells on each of the two pile heads. Though the primary application is timber piled embankments, the test results can be extrapolated to GRPSE designs in general.