This paper presents the results of a community survey that was designed to better understand the effects of permafrost degradation and coastal erosion on civil infrastructure. Observations were collected from residents in four Arctic coastal communities: Point Lay, Wainwright, Utqiaġvik, and Kaktovik. All four communities are underlain by continuous ice-rich permafrost with varying degrees of degradation and coastal erosion. The types, locations, and periods of observed permafrost thaw and coastal erosion were elicited. Survey participants also reported the types of civil infrastructure being affected by permafrost degradation and coastal erosion and any damage to residential buildings. Most survey participants reported that coastal erosion has been occurring for a longer period than permafrost thaw. Surface water ponding, ground surface collapse, and differential ground settlement are the three types of changes in ground surface manifested by permafrost degradation that are most frequently reported by the participants, while houses are reported as the most affected type of infrastructure in the Arctic coastal communities. Wall cracking and house tilting are the most commonly reported types of residential building damage. The effects of permafrost degradation and coastal erosion on civil infrastructure vary between communities. Locations of observed permafrost degradation and coastal erosion collected from all survey participants in each community were stacked using heatmap data visualization. The heatmaps constructed using the community survey data are reasonably consistent with modeled data synthesized from the scientific literature. This study shows a useful approach to coproduce knowledge with Arctic residents to identify locations of permafrost thaw and coastal erosion at higher spatial resolution as well as the types of infrastructure damage of most concern to Arctic residents.

This paper presents a large-scale direct shear testing of tire-derived aggregate (TDA) of large sizes (25–75 mm). The objective of this research is to obtain and compare the shear resistances of large-sized TDA and TDA in contact with sand, concrete, and geosynthetics. TDAs are pieces of processed and shredded waste tires that can be used as lightweight and quick fills for embankments, subgrades, and retaining walls. A large-scale direct shear apparatus was designed and constructed. The shear box dimensions were 79 cm wide, 80 cm long, and 122 cm tall. The lower shear box was driven by a hydraulic piston, while the upper shear box remained stationary. The horizontal shear forces, shear displacements, and vertical forces were recorded by an automatic data acquisition system. Three normal loads were applied on the TDA to simulate overburden pressures of 24, 48, and 96 kPa (or 500, 1,000, and $\mathrm{2,000}\mathrm{lb}/{\mathrm{ft}}^2$ ). Duplicate tests were performed to verify the repeatability. The control tests using sand proved that the equipment could obtain comparable and slightly conservative shear strength. The Mohr-Coulomb failure criterion was used to obtain the cohesion (or adhesion) and friction angles of the TDA. The shear testing revealed the difference of failure mechanisms of TDA and sand. For TDA, no peak shear resistance was observed during the entire shearing, and shear resistance continued to increase until the test was terminated at sufficient shear displacement. Further analysis revealed that the shear strength parameters of TDA increase with shear deformation; this represents a challenge in selecting the design parameters of TDAs. The shear strengths of TDA and TDA in contact with other materials are dictated primarily by friction. The friction angles of TDA, TDA on sand, and TDA on concrete are very similar (in a range of 35–39°).

The thawing of permafrost in the Arctic has led to an increase in coastal land loss, flooding, and ground subsidence, seriously threatening civil infrastructure and coastal communities. However, a lack of tools for synthetic hazard assessment of the Arctic coast has hindered effective response measures. We developed a holistic framework, the Arctic Coastal Hazard Index (ACHI), to assess the vulnerability of Arctic coasts to permafrost thawing, coastal erosion, and coastal flooding. We quantified the coastal permafrost thaw potential (PTP) through regional assessment of thaw subsidence using ground settlement index. The calculations of the ground settlement index involve utilizing projections of permafrost conditions, including future regional mean annual ground temperature, active layer thickness, and talik thickness. The predicted thaw subsidence was validated through a comparison with observed long-term subsidence data. The ACHI incorporates the PTP into seven physical and ecological variables for coastal hazard assessment: shoreline type, habitat, relief, wind exposure, wave exposure, surge potential, and sea-level rise. The coastal hazard assessment was conducted for each 1 km² coastline of North Slope Borough, Alaska in the 2060s under the Representative Concentration Pathway 4.5 and 8.5 forcing scenarios. The areas that are prone to coastal hazards were identified by mapping the distribution pattern of the ACHI. The calculated coastal hazards potential was subjected to validation by comparing it with the observed and historical long-term coastal erosion mean rates. This framework for Arctic coastal assessment may assist policy and decision-making for adaptation, mitigation strategies, and civil infrastructure planning.

Subsurface processes significantly influence surface dynamics in permafrost regions, necessitating utilizing diverse geophysical methods to reliably constrain permafrost characteristics. This research uses multiple geophysical techniques to explore the spatial variability of permafrost in undisturbed tundra and its degradation in disturbed tundra in Utqiaġvik, Alaska. Here, we integrate multiple quantitative techniques, including multichannel analysis of surface waves (MASW), electrical resistivity tomography (ERT), and ground temperature sensing, to study heterogeneity in permafrost’s geophysical characteristics. MASW results reveal active layer shear wave velocities (V_s) between 240 and 370 m/s, and permafrost V_s between 450 and 1,700 m/s, typically showing a low‐high‐low velocity pattern. Additionally, we find an inverse relationship between in situ V_s and ground temperature measurements. The V_s profiles along with electrical resistivity profiles reveal cryostructures such as cryopeg and ice‐rich zones in the permafrost layer. The integrated results of MASW and ERT provide valuable information for characterizing permafrost heterogeneity and cryostructure. Corroboration of these geophysical observations with permafrost core samples’ stratigraphies and salinity measurements further validates these findings. This combination of geophysical and temperature sensing methods along with permafrost core sampling confirms a robust approach for assessing permafrost’s spatial variability in coastal environments. Our results also indicate that civil infrastructure systems such as gravel roads and pile foundations affect permafrost by thickening the active layer, lowering the V_s, and reducing heterogeneity. We show how the resulting V_s profiles can be used to estimate key parameters for designing buildings in permafrost regions and maintaining existing infrastructure in polar regions.

Geosynthetic reinforced soil (GRS) walls and abutments are increasingly used to support transportation infrastructure. A pressing question in their response is the amount of horizontal deflection expected under service loads. This paper presents an evaluation of six methods for predicting the lateral deformation of GRS walls and abutments, namely the FHWA, Geoservice, CTI, Jewell-Milligan, Wu, and Adams methods. Field and laboratory performances of 17 GRS walls and abutments are compared with the predicted results from the six methods. A statistical analysis is then used to evaluate the conservativeness, accuracy, and reliability of these methods in predicting the maximum lateral deformation of GRS walls. The Adams method is the most accurate method for predicting the maximum lateral deformation if the amount of vertical deformation is reasonably known. Among the Geoservice, Jewell-Milligan, and Wu methods, which have the ability to predict the lateral deformation of GRS walls at various elevations where reinforcements are located, the Wu method is the most accurate and reliable method for predicting the lateral deformation of GRS walls.