Permafrost Slopes Research Articles

Thermo-seismic performance of the novel thermal anchor pipe frame (TAPF) structure for supporting slope in earthquake-prone permafrost regions

The thermal anchor pipe frame (TAPF) structure is a new type of permafrost slope support technology, but its thermo-seismic characteristics are still unclear. In this paper, the coupled hydro-thermal-dynamic model of the thermal anchor pipe frame permafrost slope system is established. The cooling performance of the TAPF structure is investigated and the seismic responses are comparatively analyzed for different freeze-thaw periods. Results show that the presence of “elliptical” freezing cores with lower temperatures (which ranged from −3.94 to −5.36 °C) near the active layer at the end of the thawing period, which raised the permafrost table. The strip-shaped unfrozen moisture accumulation layer appears near the upper part of the thawing front at the highest temperature in the warm season. The peak acceleration response is the largest on October 15, 52.3% greater than the peak acceleration on April 15. The peak axial force of the thermal anchor pipe during the freezing period was 119 kN, which was 32.2% greater than that during the thawing period, and the peak total axial force after the earthquake appeared at the location of the freeze-thaw interface, and the axial force of the heat-transfer free section is greater than that of the anchored section. The frame structure is sensitive to earthquakes during the freezing period, and plastic bending damage may occur, especially at connection locations with thermal anchor pipes. Seasonal effects also have a strong influence on the shape of the acceleration response spectrum. The results can provide useful references for the maintenance and safe operation of permafrost slopes along the Qinghai-Tibet Project as well as for the seismic design of the new structure.

Seismic response of permafrost slopes supported by the thermal anchor pipe frame: Theoretical analysis and shaking table test verification

To study the seismic response of the thermal anchor pipe frame supporting permafrost slope system, the coupled dynamic interaction model of the permafrost slope with the thermal anchor pipe frame in thawing and freezing periods was established by taking into account the stratification characteristics of the permafrost slope in different typical seasons, respectively. Based on D'Alembert's principle and Dirac's function, the coupled vibration equilibrium differential equations are given and the seismic response of the system is analyzed for different periods. The reliability of the proposed model was further verified through shaking table tests. The results show that the acceleration response at different positions during both freezing and thawing periods is similar to the initial loading seismic wave shape. The peak acceleration and velocity during the thawing period is greater than that during the freezing period. The shear force and bending moment of the frame column are distributed alternately positive and negative along its height. The incremental dynamic shear force and bending moment are greater during the thawing period. However, the peak bending moments and shear forces are greater during the freezing period when the combined effects of frost and earthquakes. The peak bending moment occurs at the position of the first layer of the thermal anchor pipe, and the shear force suddenly changes near the thermal anchor pipe. In seismic design, attention should be paid to checking the internal force of the frame column during the freezing period to prevent plastic bending failure. The results contribute to further understanding the dynamic interaction mechanism of the thermal anchor pipe frame permafrost slope system, which has important practical significance for its seismic resistance.

Machine learning-based predictions of current and future susceptibility to retrogressive thaw slumps across the Northern Hemisphere

Retrogressive thaw slumps (RTSs) caused by the thawing of ground ice on permafrost slopes have dramatically increased and become a common permafrost hazard across the Northern Hemisphere during previous decades. However, a gap remains in our comprehensive understanding of the spatial controlling factors, including the climate and terrain, that are conducive to these RTSs at a global scale. Using machine learning methodologies, we mapped the current and future RTSs susceptibility distributions by incorporating a range of environmental factors and RTSs inventories. We identified freezing-degree days and maximum summer rainfall as the primary environmental factors affecting RTSs susceptibility. The final ensemble susceptibility map suggests that regions with high to very high susceptibility could constitute (11.6 ± 0.78)% of the Northern Hemisphere's permafrost region. When juxtaposed with the current (2000–2020) RTSs susceptibility map, the total area with high to very high susceptibility could witness an increase ranging from (31.7 ± 0.65)% (SSP585) to (51.9 ± 0.73)% (SSP126) by the 2041–2060. The insights gleaned from this study not only offer valuable implications for engineering applications across the Northern Hemisphere, but also provide a long-term insight into the potential change of RTSs in permafrost regions in response to climate change.

Numerical Simulations of Failure Mechanism for Silty Clay Slopes in Seasonally Frozen Ground

Landslide damage to soil graben slopes in seasonal freezing zones is a crucial concern for highway slope safety, particularly in the northeast region of China where permafrost thawing is significant during the spring. The region has abundant seasonal permafrost and mostly comprises powdery clay soil that is susceptible to landslides due to persistent frost and thaw cycles. The collapse of a slope due to thawing and sliding not only disrupts highway operations but also generates lasting implications for environmental stability, economic resilience, and social well-being. By understanding and addressing the underlying mechanisms causing such events, we can directly contribute to the sustainable development of the region. Based on the Suihua–Beian highway graben slope landslide-management project, this paper establishes a three-dimensional finite element model of a seasonal permafrost slope using COMSOL Multiphysics 6.1 finite element numerical analysis software. Additionally, the PDE mathematical module of the software is redeveloped to perform hydrothermal-coupling calculations of seasonal permafrost slopes. The simulation results yielded the dynamic distribution characteristics of the temperature and seepage field on the slope during the F–T process. The mechanism behind the slope thawing and sliding was also unveiled. The findings provide crucial technical support for the rational analysis of slope stability, prevention of sliding, and effective control measures, establishing a direct linkage to the promotion of sustainable infrastructure development in the context of transportation and roadway engineering.

Allometric scaling of retrogressive thaw slumps

Abstract. In the warming Arctic, retrogressive thaw slumping (RTS) has emerged as the primary thermokarst modifier of ice-rich permafrost slopes, raising urgency to investigate the distribution and intensification of disturbances and the cascade of effects. Tracking RTS is challenging due to the constraints of remote sensing products and a narrow understanding of complex, thaw-driven landforms; however, high-resolution elevation models provide new insights into geomorphic change. Structural traits, such as RTS depth of thaw or volume, can be obtained through allometric scaling. To address fundamental knowledge gaps related to area–volume scaling of RTS, a suitable surface interpolation technique was first needed to model pre-disturbance topography upon which volume estimates could be based. Among eight methods with 32 parameterizations, natural neighbour surface interpolation achieved the best precision in reconstructing pre-disturbed slope topography (90th percentile root mean square difference ±1.0 m). An inverse association between RTS volume and relative volumetric error was observed, with uncertainties < 10 % for large slumps and < 20 % for small to medium slumps. Second, a multisource slump inventory (MSI) for two study areas in the Beaufort Delta (Canada) region was developed to characterize the diverse range of disturbance morphologies and activity levels, which provided consistent characterization of thaw-slump-affected slopes between regions and through time. The MSI delineation of high-resolution hillshade digital elevation models (DEMs) for three time periods (airborne stereo-imagery, lidar, ArcticDEM) revealed temporal and spatial trends in these chronic mass-wasting features. For example, in the Tuktoyaktuk Coastlands, a +38 % increase in active RTS counts and +69 % increase in total active surface area were observed between 2004 and 2016. However, the total disturbance area of RTS-affected terrain did not change considerably (+3.5 %) because the vast majority of active thaw slumping processes occurred in association with past disturbances. Interpretation of thaw-driven change is thus dependent on how active RTS is defined to support disturbance inventories. Our results highlight that active RTS is tightly linked to past disturbances, underscoring the importance of inventorying inactive scar areas. Third, the pre-disturbance topographies, MSI digitizations, and DEMs were integrated to explore allometric scaling relationships between RTS area and eroded volume. The power-law model indicated non-linearity in the rates of RTS expansion and intensification across scales (adj-R2 of 0.85, n= 1522) but also revealed that elongated, shoreline RTS reflects outliers poorly represented by the modelling. These results indicate that variation in the allometric scaling of RTS populations is based on morphometry, terrain position, and complexity of the disturbance area, as well as the method and ontology by which slumps are inventoried. This study highlights the importance of linking field-based knowledge to feature identification and the utility of high-resolution DEMs in quantifying rates of RTS erosion beyond tracking changes in the planimetric area.

Effect of temperature change on the thaw-induced permafrost slope failure based on thermal-hydro-mechanical coupling

Effect of temperature change on the thaw-induced permafrost slope failure based on thermal-hydro-mechanical coupling

Field investigation on the spatiotemporal thermal-deformation characteristics of a composite embankment with two-phase closed thermosyphons on a permafrost slope

Field investigation on the spatiotemporal thermal-deformation characteristics of a composite embankment with two-phase closed thermosyphons on a permafrost slope

Recent Intensification (2004–2020) of Permafrost Mass‐Wasting in the Central Mackenzie Valley Foothills Is a Legacy of Past Forest Fire Disturbances

AbstractThe effects of recent climate change are accelerating permafrost thaw, including ice‐rich landscapes of the western Canadian Arctic. However, regional drivers of permafrost slope failure in hillslopes with warm, thin permafrost remain poorly understood. Repeat satellite imagery (1984–2020) indicates rapid increases in retrogressive thaw slumps (RTSs) and deep‐seated permafrost landslides (DSPLs) since 2004, indicating a change in slope stability thresholds in an area that otherwise appeared thaw stable. The widespread occurrence of DSPL represents a contrasting geomorphic response to the RTS‐dominated ice‐rich permafrost landscapes. In this study area, RTS and DSPL occur predominantly in areas that were burned by forest fires in the 1990s, indicating a legacy thermal disturbance that preconditioned permafrost hillslopes for failure. The relations between historic fires and the later development of widespread permafrost slope failures represent an outstanding example of the complex interactions between inherited landscape sensitivity in ice‐rich terrain and ongoing climate change.

Study on stability of permafrost slopes during thawing

Study on stability of permafrost slopes during thawing

An integrated observation dataset of the hydrological and thermal deformation in permafrost slopes and engineering infrastructure in the Qinghai–Tibet Engineering Corridor

Abstract. Across the Qinghai–Tibet Plateau (QTP) there is a narrow engineering corridor with widely distributed slopes called the Qinghai–Tibet Engineering Corridor (QTEC), where a variety of important infrastructures are concentrated. These facilities are transportation routes for people, materials, energy, etc. from inland China to the Tibet Autonomous Region. From Golmud to Lhasa, the engineering corridor covers 632 km of permafrost containing the densely developed Qinghai–Tibet Railway and Qinghai–Tibet Highway, as well as power and communication towers. Slope failure in permafrost regions, caused by permafrost degradation, ground ice melting, etc., affects the engineering construction and permafrost environments in the QTEC. We implement a variety of sensors to monitor the hydrological and thermal deformation between permafrost slopes and permafrost engineering projects in the corridor. In addition to soil temperature and moisture sensors, the global navigation satellite system (GNSS), terrestrial laser scanning (TLS), and unmanned aerial vehicles (UAVs) were adopted to monitor the spatial distribution and changes in thermal deformation. An integrated dataset of hydrological and thermal deformation in permafrost engineering and slopes in the QTEC from the 1950s to 2020, including meteorological and ground observations, TLS point cloud data, and RGB and thermal infrared (TIR) images, can be of great value for estimating the hydrological and thermal impact and stability between engineering and slopes under the influence of climate change and engineering disturbance. The dataset and code were uploaded to the Zenodo repository and can be accessed through https://zenodo.org/communities/qtec (last access: 23 June 2021), including meteorological and ground observations at https://doi.org/10.5281/zenodo.5009871 (Luo et al., 2020d), TLS measurements at https://doi.org/10.5281/zenodo.5009558 (Luo et al., 2020a), UAV RGB and TIR images at https://doi.org/10.5281/zenodo.5016192 (Luo et al., 2020b), and R code for permafrost indices and visualisation at https://doi.org/10.5281/zenodo.5002981 (Luo et al., 2020c).

Machine learning-based thermokarst landslide susceptibility modeling across the permafrost region on the Qinghai-Tibet Plateau

Thermokarst landslides (TL) caused by the thaw of ground ice in permafrost slopes are increasing on the Qinghai-Tibet Plateau (QTP), but the understanding of the spatially suitable environmental conditions including terrains and climate for them has not been fully established. Here, we applied multiple machine learning models and their ensemble to explore factors controlling the TL and map its susceptibility at a fine resolution. The models were calibrated and validated using a split-sample approach based on an inventory of TLs from the remote sensing data. The models indicated that summer air temperature and rainfall were the most two important factors controlling the occurrence and distribution of TLs, provided that other geomorphic conditions (i.e., slope, solar radiation, and fine soil) were suitable. The final ensemble susceptibility map based on downscaled climate data and terrain data suggested that ca. 1.4% of the QTP land was classified in high- to very high-susceptibility zone, which is likely to increase in response to future climate change. This study integrated local topography and climate in susceptibility modeling and provided new insights into the geomorphic sensitivity to climate change but also the engineering support over the QTP.

Analyses of the Impacts of Climate Change and Forest Fire on Cold Region Slopes Stability by Random Finite Element Method

Increasing number of landslides occurred in the cold regions over the past decades due to rising temperature or forest fires associated with climate change. The instability of thawing slopes caused serious damages to transportation infrastructure, residential properties, and losses of human lives. These types of landslides, however, are difficult to analyze by the traditional limit equilibrium methods due to the coupled thermos-hydro-mechanical multiphysics processes involved. This paper describes a novel microstructure-based random finite element model (RFEM) to simulate the stability of permafrost slope subjected to climate change, including the increasing extent of thawing by warm atmosphere and thermal load due to forest fire. The properties of frozen soil are captured with random finite element model incorporating soil-phase coding. The thermomechanical responses of a permafrost slope are simulated to obtain the temperature, displacement, and stress fields. From these, the local factors of safety are obtained, which predict failure slumps along the slope that are consistent with the field-observed failure behaviors in permafrost slopes. The effects of climate change on the permafrost slope stability are analyzed for the years of 1956, 2017, and 2045. The results demonstrated appreciable amount of effects of climate change on the extent of slope failure zones. Forest fire led to melting of frozen soil and also affects the slope stability primarily in the shallow depth.

Thermo-mechanical coupling analysis and software development

In order to quickly and accurately grasp the law of freeze-thaw reaction of permafrost slopes, based on the hydro-thermal-mechanical coupling theory, relying on MATLto compile a finite element program that can reflect the multi-field coupling mechanism of the soil. This test is in good agreement with the classic test, which verifies the reliability of the program. Based on this, the paper developed a set of water-thermal-mechanical coupling analysis software for permafrost slopes that can run independently and is easy to operate. The software?s functions and development process are introduced. The response characteristics of frozen soil slopes under freezing and thawing are analyzed in combination with the example papers. The results show that the slope temperature, moisture, stress and displacement are obviously different at different times. The maximum shear stress band appears at the freezing-thawing interface of the slope. The horizontal displacement of the slope is basically the same along the slope when the freezing is completed. At the end of the thawing period, the upper part and the lower part are large. The horizontal displacement and unfrozen water content of the slope during the thawing period are larger than those during the freezing period, but the maximum shear stress is small and the stability of permafrost in the warm season is poor. It has important application value for freeze-thaw calculation of frozen soil slope engineering.

Fluvial Response to a Period of Hydrometeorological Change and Landscape Disturbance in the Canadian High Arctic

AbstractRecords of fluvial suspended sediment fluxes are sensitive indicators of hydrometeorological and permafrost change. Here we document the watershed‐scale suspended sediment flux response to a period of hydrometeorological change and landscape disturbance in two High Arctic rivers. Net in‐channel and extra‐channel sediment storage and changing hydrometeorological conditions dampen the downstream transport of increased sediment delivery from localized permafrost slope disturbances. Our results show that the impact of permafrost disturbance is likely a smaller effect than a shift toward a pluvially (rainfall) dominated hydrological regime in these environments. Suspended sediment transport is energy limited under contemporary hydrometeorological conditions, and the transition from a nival to pluvial dominated flow and sediment transfer regime will likely accelerate landscape change in the High Arctic.

UAV-based spatiotemporal thermal patterns of permafrost slopes along the Qinghai–Tibet Engineering Corridor

Thermal infrared remote sensing technology based on unmanned aerial vehicle (UAV) was applied to estimate the spatial distribution of ground surface temperatures on permafrost slopes and evaluate the thermal influence of nearby engineering infrastructure. This paper presents a method that uses a miniature UAV with a thermal infrared sensor to collect thermal images with high temporal–spatial resolution. Moreover, spatial analysis is used to effectively evaluate the relationship between engineering infrastructure and permafrost slopes in the Qinghai–Tibet Engineering Corridor (QTEC), China. To test the method, aerial measurements were collected from 11:00 to 17:00 in July and August of 2017 at two permafrost slopes along the QTEC, where the Qinghai–Tibet Highway (QTH), Qinghai–Tibet Railway (QTR), and electric towers were built on permafrost slopes. The differences of ground surface temperature between the highway and the surrounding soil were largest at 11:00 and 17:00; the differences were smaller at noon to approximately 15:00 when the difference was minimal, and the differences began to increase after 15:00. The distances of the thermal influence of the highway, railway, and electric towers on the surrounding permafrost slopes are approximately 12–14, 8–10, and 2–4 m, respectively. The results indicate that the degree of influence of engineering structures on permafrost slopes is as follows: QTH > QTR > electric towers. This study is the first to use UAV-based thermal infrared remote sensing to evaluate the thermal dynamics of permafrost slopes along the QTEC. These results may provide new insights into the future design, construction, and maintenance of engineering structures on permafrost slopes.

Thermo-seismic characteristics of a crushed-rock interlayer embankment on a permafrost slope

Crushed rock is a highly porous medium widely used to cool embankments in permafrost regions. The thermal transfer of a crushed-rock embankment (CRE) was fully investigated by experimental and numerical methods. However, the CRE's mechanical process, especially under dynamic loading, is a key factor for its safe operation but has been ignored. To study the dynamic characteristics of the CRE, we proposed a thermo-dynamic coupled model for the CRE, selected a crushed-rock interlayer embankment (CRIE) on a permafrost slope, and conducted a series of numerical computations over four seasons in its 20th service year. The CRIE temperature changed seasonally, causing seasonal differences in mechanical behaviors and seismic responses. By comparing the acceleration, velocity, displacement and pore water pressure responses of the CRIE, the seismic damage mechanism of the CRIE is analyzed and the time at which the earthquake-induced damage of the CRIE is the heaviest among these four seasons is identified. The numerical model and results in the study can provide theoretical support to the construction and maintenance of the CRIE as well as a reference for further study of the CRE in permafrost regions.

20 - Characterization of Novel Oral Splicing Modulator, H3B-8800, Identifies the Mechanistic Basis for its Preferential Lethality Towards Spliceosome-Mutant Myeloid Malignancy Models

Crushed rock is a highly porous medium widely used to cool embankments in permafrost regions. The thermal transfer of a crushed-rock embankment (CRE) was fully investigated by experimental and numerical methods. However, the CRE's mechanical process, especially under dynamic loading, is a key factor for its safe operation but has been ignored. To study the dynamic characteristics of the CRE, we proposed a thermo-dynamic coupled model for the CRE, selected a crushed-rock interlayer embankment (CRIE) on a permafrost slope, and conducted a series of numerical computations over four seasons in its 20th service year. The CRIE temperature changed seasonally, causing seasonal differences in mechanical behaviors and seismic responses. By comparing the acceleration, velocity, displacement and pore water pressure responses of the CRIE, the seismic damage mechanism of the CRIE is analyzed and the time at which the earthquake-induced damage of the CRIE is the heaviest among these four seasons is identified. The numerical model and results in the study can provide theoretical support to the construction and maintenance of the CRIE as well as a reference for further study of the CRE in permafrost regions.

Terrain Controls and Landscape-Scale Susceptibility Modelling of Active-Layer Detachments, Sabine Peninsula, Melville Island, Nunavut

Modelling the susceptibility of permafrost slopes to disturbance can identify areas at risk to future disturbance and result in safer infrastructure and resource development in the Arctic. In this study, we use terrain attributes derived from a digital elevation model, an inventory of permafrost slope disturbances known as active-layer detachments (ALDs) and generalised additive modelling to produce a map of permafrost slope disturbance susceptibility for an area on northern Melville Island, in the Canadian High Arctic. By examining terrain variables and their relative importance, we identified factors important for initiating slope disturbance. The model was calibrated and validated using 70 and 30 per cent of a data-set of 760 mapped ALDs, including disturbed and randomised undisturbed samples. The generalised additive model calibrated and validated very well, with areas under the receiver operating characteristic curve of 0.89 and 0.81, respectively, demonstrating its effectiveness at predicting disturbed and undisturbed samples. ALDs were most likely to occur below the marine limit on slope angles between 3 and 10° and in areas with low values of potential incoming solar radiation (north-facing slopes). Copyright © 2016 John Wiley & Sons, Ltd.

Permafrost thaw and intense thermokarst activity decreases abundance of stream benthic macroinvertebrates.

Intensification of permafrost thaw has increased the frequency and magnitude of large permafrost slope disturbances (mega slumps) in glaciated terrain of northwestern Canada. Individual thermokarst disturbances up to 40ha in area have made large volumes of previously frozen sediments available for leaching and transport to adjacent streams, significantly increasing sediment and solute loads in these systems. To test the effects of this climate-sensitive disturbance regime on the ecology of Arctic streams, we explored the relationship between physical and chemical variables and benthic macroinvertebrate communities in disturbed and undisturbed stream reaches in the Peel Plateau, Northwest Territories, Canada. Highly disturbed and undisturbed stream reaches differed with respect to taxonomic composition and invertebrate abundance. Minimally disturbed reaches were not differentiated by these variables but rather were distributed along a disturbance gradient between highly disturbed and undisturbed sites. In particular, there was evidence of a strong negative relationship between macroinvertebrate abundance and total suspended solids, and a positive relationship between abundance and the distance from the disturbance. Increases in both sediments and nutrients appear to be the proximate cause of community differences in highly disturbed streams. Declines in macroinvertebrate abundance in response to slump activity have implications for the food webs of these systems, potentially leading to negative impacts on higher trophic levels, such as fish. Furthermore, the disturbance impacts on stream health can be expected to intensify as climate change increases the frequency and magnitude of thermokarst.

Temporal variability of diverse mountain permafrost slope movements derived from multi-year daily GPS data, Mattertal, Switzerland

In this study, high resolution surface measurements of diverse slope movements are compared to environmental factors such as ground surface temperature (GST) and snow cover, in order to reveal and compare velocity fluctuations caused by changing environmental conditions. The data cover 2 years (2011–2013) of Global Positioning System (GPS) and GST measurements at 18 locations on various slope movement types within an alpine study site in permafrost (Mattertal, Switzerland). Velocities have been estimated based on accurate daily GPS solutions. The mean annual velocities (MAV) observed at all GPS stations varied between 0.006 and 6.3 ma−1. MAV were higher in the period 2013 compared to 2012 at all stations. The acceleration in 2013 was accompanied by a longer duration of the snow cover and zero curtain and slightly lower GST. The amplitude (0–600 %) and the timing of the intra-annual variability were generally similar in both periods. At most stations, an annual cycle in the movement signal was observed, with a phase lag of 1–4 months to GST. Maximum velocity typically occurred in late summer and autumn, and minimum velocity in late winter and beginning of spring. The onset of acceleration always started in spring during the snowmelt period. At two stations located on steep rock glacier tongues, overprinted on the annual cycle, short-term peaks of velocity increase, occurred during the snowmelt period, indicating a strong influence of meltwater.