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The mapping and classification of active landslides in high mountainous regions provide crucial information about the location and types of geohazards. Additionally, this process plays a vital role in ensuring the safety of the geological environments in mountainous towns. In this study, we presented a refined InSAR approach for mapping and classifying active landslide hazards in Deqin County, Tibetan Plateau, China. The study area is characterized by a high altitude and extremely rugged terrain. Consequently, conventional InSAR methods are limited in precisely estimating landslide deformation owing to severe atmospheric delays. To this end, we first propose a block-based linear model to correct tropospheric artifacts. This model considers the spatial variability of the atmosphere and provides an opportunity to accurately estimate heterogeneous atmospheric delays over high mountainous areas without any external data. Compared with the traditional global-window linear model and the GACOS approach, the new method demonstrated outstanding performance in reducing atmospheric artifacts. Second, based on the knowledge mapping of landslide types, we proposed a semi-automatic procedure to map and classify landslides using InSAR-derived displacements and auxiliary data (i.e., C-index and high resolution optical images). Our results obtained from ascending and escending Sentinel-1 images revealed, for the first time, that there were 317 active landslides in Deqin County between May 2017 and June 2021. Among these, 10.7% were associated with slide activity, 7.9% with fall deformation, and the majority (81.4%) with flow movement. These results were cross-verified and evaluated using an a priori inventory map obtained from the visual interpretation of optical images and geological field surveys. This study demonstrates that InSAR can accurately map and classify active landslides over difficult mountainous terrains, provided the associated phase errors are effectively restrained.

A growing rock engineering activity in cold regions is facing the threat of freeze-thaw (FT) weathering, especially in high mountains where the sunny-shady slope effects strongly control the difference in weathering behavior of rocks. In this paper, an investigation of the degradation of petrophysical characteristics of sandstone specimens subjected to FT cycle tests to simulate the sunny-shady slope effects is presented. To this aim, non-destructive and repeatable testing techniques including weight, ultrasonic waves, and nuclear magnetic resonance methods on standard specimens were performed. For the sunny slope specimens, accompanied by the enlargement of small pores, 100 FT cycles caused a significant decrease in P-wave velocity with an average of 23%, but a consistent rise of 0.18% in mass loss, 34% in porosity, 67% in pore geometrical mean radius, and a remarkable 14.5-fold increase in permeability. However, slight changes with some abnormal trends in physical parameters of the shady slope specimens were observed during FT cycling, which can be attributed to superficial granular disaggregation and pore throat obstruction. Thermal shocks enhance rock weathering on sunny slopes during FT cycles, while FT weathering on shady slopes is restricted to the small pores and the superficial cover. These two factors are primarily responsible for the differences in FT weathering intensity between sunny and shady slopes. The conclusions derived from the interpretation of the experimental results may provide theoretical guidance for the design of slope-failure prevention measures and the selection of transportation routes in cold mountainous regions.

Monitoring of mining-induced subsidence dynamics enables to the exploration and analysis of changes in the direction of surface deformation caused by the extraction of underground resources. Both human activities and geological environments affect these changes to a large extent. LuTan-1 (LT-1) satellite as the first SAR mission with L-band bistatic spaceborne in China, provides continuous imagery for analyzing surface deformations through differential SAR interferometry, offering valuable velocity results using stacking techniques. The results of the subsidence bowl obtained from LT-1 closely align with those from Sentinel-1 in the almost same period in Datong, China. Furthermore, we validated the DInSAR results of LT-1 and Sentinel-1 using continuous GNSS data from the corresponding time frames. Notably, we observed a significant improvement in the quality and accuracy of LT-1 datasets due to the in-orbit performance test. Finally, we explored the surface deformation dynamics pertinent to mining activities using DInSAR results obtained from four different time periods. These results revealed substantial changes on the shape and spatial location of the subsidence bowls over time. This indicates a maximum horizontal displacement in the directional change of approximate 1.429 km and an average face advance rate between 0.724 and 6.355 m/day within about a one-year time period. Lastly, velocity and accumulated displacement gradient maps, derived from stacking results, were overlaid to the distribution of critical infrastructures in the study areas to assess their exposure to mining subsidence, and a validation process was carried out using GF-7 optical images. This study emphasizes the potential of LT-1 to monitor mining subsidence dynamics and its capability for joint analysis with the exposure of critical infrastructures.

Steep fill–bedrock interfaces usually appear in many filling soil infrastructures, such as airports, houses, and road embankments in mountainous areas, when the excavation of rock slopes is constrained. These interfaces are prone to be tensioned up to failure, which easily triggers landslides of fill slopes. The anchor system buried in the fill soil, named radial cable system, was proposed for effectively enhancing the stability of steep fill–bedrock interfaces. At the interface, the steel ropes of the anchor section cable were equally divided into three subcables with a radial distribution. The pullout performance, failure evolution, and branching effect of the radial cable coupled with anchor plates were studied by a pullout test (in a laboratory setup) and a numerical simulation. The results showed that (1) the ultimate pullout capacities (Pu) of the radial cables were 193.53%–312.94% (for the 7 mm diameter of the anchor plate) and 141.25%–247.50% (for the 10 mm diameter of the anchor plate) greater than those of the single cables; (2) the pullout performance of the radial cable was significantly improved with an increase in the diameter of the anchor plate, and the optimal radial inclined angle of subcables coupled with anchor plates was 15°; (3) the soil surrounding the radial cable showed a progressive failure pattern, and its failure area was basically a symmetric conical; and (4) the radial cable can better reinforce the steep fill–rock interface than the conventional cable, as verified by a hill-fill project. The results of this study provide some new and important guidelines for the design and application of the radial cable system.

[EN] Slope failures, subsidence, earthworks, consolidation of waste dumps, and erosion are typical active deformation processes that pose a significant hazard in current and abandoned mining areas, given their considerable potential to produce damage and affect the population at large. This work proves the potential of exploiting space-borne InSAR and airborne LiDAR techniques, combined with data inferred through a simple slope stability geotechnical model, to obtain and update inventory maps of active deformations in mining areas. The proposed approach is illustrated by analyzing the region of Sierra de Cartagena-La Union (Murcia), a mountainous mining area in southeast Spain. Firstly, we processed Sentinel-1 InSAR imagery acquired both in ascending and descending orbits covering the period from October 2016 to November 2021. The obtained ascending and descending deformation velocities were then separately post-processed to semi-automatically generate two active deformation areas (ADA) maps by using ADATool. Subsequently, the PS-InSAR LOS displacements of the ascending and descending tracks were decomposed into vertical and east-west components. Complementarily, open-access, and non-customized LiDAR point clouds were used to analyze surface changes and movements. Furthermore, a slope stability safety factor (SF) map was obtained over the study area adopting a simple infinite slope stability model. Finally, the InSAR-derived maps, the LiDAR-derived map, and the SF map were integrated to update a previously published landslides’ inventory map and to perform a preliminary classification of the different active deformation areas with the support of optical images and a geological map. Complementarily, a level of activity index is defined to state the reliability of the detected ADA. A total of 28, 19, 5, and 12 ADAs were identified through ascending, descending, horizontal, and vertical InSAR datasets, respectively, and 58 ADAs from the LiDAR change detection map. The

[EN] Floods greatly impact human settlements in flood risk areas, such as floodplains and coastal lowlands, following heavy rainfall. The Alto Guadalentin valley, an orogenic tectonic depression, experiences extreme flash floods and land subsidence due to groundwater withdrawal, rendering it one of Europe's fastest subsiding regions. In this study, we compared two 2D flood event models representing different land subsidence scenarios for 1992 and 2016. To determine the flooded area and water depth variations due to land subsidence, the Hydrologic Engineering Centre River Analysis System 2D (HEC-RAS 2D) model was used to simulate flood inundation by the Alto Guadalentin River and its tributaries. Synthetic aperture radar (SAR) satellite (ERS, ENVISAT, and Cosmo-SkyMED) images were employed, along with the interferometric SAR (InSAR) technique, to calculate the magnitude and spatial distribution of land subsidence. By analysing the accumulated subsidence distributions obtained from InSAR, the original topography of the valley in 1992 and 2016 was reconstructed. These digital surface models (DSMs) were then used to generate 2D hydraulic models, simulating flood scenarios in the unsteady mode. The results demonstrated significant changes in the water surface elevation over the 14-year period, with a 2.04 km2 increase in areas with water depths exceeding 0.7 m. These findings were utilized to create a flood risk map and assess the economic flood risk. The data highlight the crucial role of land subsidence in determining the inundation risk in the Alto Guadalentin valley, providing valuable insights for emergency management and civil protection against future potential flooding events.