Search Results (26)

Landslide risks in open-pit mine areas are heightened by artificial slope modifications necessary for mining operations, endangering human life and property. On 22 February 2023, a catastrophic landslide occurred at the Xinjing Open-Pit Coal Mine in Inner Mongolia, China, resulting in 53 fatalities and economic losses totaling 28.7 million USD. Investigating the pre-, co-, and post-failure deformation processes and exploring the potential driving mechanisms are crucial to preventing similar tragedies. In this study, we used multi-source optical and radar images alongside satellite geodetic methods to analyze the event. The results revealed pre-failure acceleration at the slope toe, large-scale southward displacement during collapse, and ongoing deformation across the mine area due to mining operations and waste accumulation. The collapse was primarily triggered by an excessively steep, non-compliant artificial slope design and continuous excavation at the slope’s base. Furthermore, our experiments indicated that the commonly used Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) significantly underestimated landslide deformation due to the maximum detectable deformation gradient (MDDG) limitation. In contrast, the high-spatial-resolution Fucheng-1 provided more accurate monitoring results with a higher MDDG. This underscores the importance of carefully assessing the MDDG when employing InSAR techniques to monitor rapid deformation in mining areas. Full article

Due to the increasing development of highway reconstruction and expansion projects in China, many large-span highway tunnels are being constructed near existing highway tunnels. Tunneling underneath will inevitably cause variation in the surrounding rock displacement and may even lead to collapse. In this study, based on an analysis of extensive field monitoring data from the Gucheng tunnel, the variation law for the surrounding rock full-displacement and the influence of the tunnel-face spatial effect in a large-span mudstone tunnel are analyzed. The change in the full displacement experienced the following sequence: slow pre-displacement growth → rapid increase → slow increase → gradual stability. The displacement released by the excavation of the tunnel construction accounts for 40~60% of the total displacement, and the closer to the excavation contour, the more obvious the displacement release. The final convergence value of vertical displacement is obtained by hyperbolic function regression prediction analysis. Based on this value, Lee and Hoek equations are used for parameter analysis and field-data fitting. It is concluded that the larger the proportion of the early displacement of the surrounding rock before construction to the total displacement, the smaller the influence of the tunnel-face spatial effect on the surrounding rock. The numerical simulation results are compared with actual monitoring results, and good agreement is observed. The larger the burial depth of the tunnel, the smaller the influence range in the tunnel-face spatial effect, and the more concentrated the displacement release. The variation law and the influential range for the surrounding rock full-displacement described in this paper can provide a reference for predicting and controlling the deformation during the construction of future large-span mudstone tunnels. Full article

Surface deformation caused by an earthquake is very important to study for a better understanding of the development of geological structures and seismic hazards in an active tectonic area. In this study, we estimated the surface deformation due to an earthquake along an active blind fault using Sentinel-1 SAR data. On 24 September 2019, an earthquake with 5.6 Mw and 10 km depth stroke near Mirpur, Pakistan. The Mirpur area was highly affected by this earthquake with a huge collapse and the death of 34 people. This study aims to estimate the surface deformation associated with this earthquake in Mirpur and adjacent areas. The interferometric synthetic aperture radar (InSAR) technique was applied to study earthquake-induced surface motion. InSAR data consisting of nine Sentinel-1A SAR images from 11 August 2019 to 22 October 2019 was used to investigate the pre-, co- and post-seismic deformation trends. Time series investigation revealed that there was no significant deformation in the pre-seismic time. In the co-seismic time, strong displacement was observed and in post-seismic results, small displacements were seen due to 4.4 and 3.2 Mw aftershocks. Burst overlap interferometry and offset-tracking analysis were used for more sensitive measurements in the along-track direction. Comprehensive 3D displacement was mapped with the combination of LOS and along-track offset deformation. The major outcome of our results was the confirmation of the existence of a previously unpublished blind fault in Mirpur. Previously, this fault line was triggered during the 2005 earthquake and then it was activated on 24 September 2019. Additionally, we presented the co-seismically induced rockslides and some secondary faulting evidence, most of which occurred along or close to the pre-existing blind faults. The study area already faces many problems due to natural hazards where additional surface deformations, particularly because of the earthquake with activated blind fault, have increased its vulnerability. Full article

The collapse of open-pit coal mine slopes is a kind of severe geological hazard that may cause resource waste, economic loss, and casualties. On 22 February 2023, a large-scale collapse occurred at the Xinjing Open-Pit Mine in Inner Mongolia, China, leading to the loss of 53 lives. Thus, monitoring of the slope stability is important for preventing similar potential damage. It is difficult to fully obtain the temporal and spatial information of the whole mining area using conventional ground monitoring technologies. Therefore, in this study, multi-source remote sensing methods, combined with local geological conditions, are employed to monitor the open-pit mine and analyze the causes of the accident. Firstly, based on GF-2 data, remote sensing interpretation methods are used to locate and analyze the collapse area. The results indicate that high-resolution remote sensing can delineate the collapse boundary, supporting the post-disaster rescue. Subsequently, multi-temporal Radarsat-2 and Sentinel-1A satellite data, covering the period from mining to collapse, are integrated with D-InSAR and DS-InSAR technologies to monitor the deformation of both the collapse areas and the potential risk to dump slopes. The D-InSAR result suggests that high-intensity open-pit mining may be the dominant factor affecting deformation. Furthermore, the boundary between the collapse trailing edge and the non-collapse area could be found in the DS-InSAR result. Moreover, various data sources, including DEM and geological data, are combined to analyze the causes and trends of the deformation. The results suggest that the dump slopes are stable. Meanwhile, the deformation trends of the collapse slope indicate that there may be faults or joint surfaces of the collapse trailing edge boundary. The slope angle exceeding the designed value during the mining is the main cause of the collapse. In addition, the thawing of soil moisture caused by the increase in temperature and the reduction in the mechanical properties of the rock and soil due to underground voids and coal fires also contributed to the accident. This study demonstrates that multi-source remote sensing technologies can quickly and accurately identify potential high-risk areas, which is of great significance for pre-disaster warning and post-disaster rescue. Full article

The prediction of railway embankment failure is still a global challenge for the railway industry due to the complexity of embankment failure mechanisms. In this work, the pre-failure deformation and the settlement from abnormal deformation to the final failure were investigated based on earth observation and on-site monitoring with a focus on the deformation stage and failure mechanism of railway embankments. Some new viewpoints are suggested: (1) the differential settlement of ~19 mm revealed via InSAR at the failure region of the embankment may have been caused by internal erosion after rapid drawdown. The cumulative settlement was found to increase with the decline of the lake water level. (2) The railway embankment experienced three phases of primary, secondary, and accelerated creep phases, similar to the evolution of most landslide or dam failures. However, the train loading and seepage force may have aggravated the secondary consolidation, promoting the embankment to enter the accelerated creep phase quickly. The deformation pattern was presented as an exponential curve trend. (3) The formation mechanism of embankment collapse can be summarized as “seepage failure-creep-shear slip-collapse” failure under repeated train loading and rapid drawdown. This work provides some clues for early warnings and for the development of maintenance plans. Full article

For this study, the geological engineering features and possible failure modes of the Dabenliu quarry slope in the Jinping-I Hydropower Station were qualitatively analyzed before a method for setting viscous boundary and an algorithm for modeling pre-stressed cables were embedded into a DDA (Discontinuous Deformation Analysis) computer code to analyze the deformation of the slope under seismic loading. Our simulation results revealed that the middle and upper parts of the slope slipped along the bedding joints (interlayer shear zones) and that the lower part buckled and collapsed after the slope was excavated. This is a typical slipping–buckling failure mode characterized by upper-slipping followed by lower-buckling. Based on the distribution of the simulated internal force of the anchor cables, the reinforcement scheme was adjusted by strengthening the support for the middle and lower parts of the slope, whereas the length and pre-stress of the anchor cables were reduced for the upper part of the slope. The adjusted reinforcement scheme can ensure the stability of the slope under the action of a magnitude 7 earthquake, and the slope may lose stability with no evident collapse under the action of a magnitude 8 earthquake. Finally, the simulation results were verified via a comparison with the monitoring data regarding the slope. Full article

This study investigated the high-speed cutting performance of 7050 aluminum alloy with prefabricated crystal orientations under dry-cutting conditions. Three specimens with different crystal orientations were prefabricated using pre-deformations of 10, 15, and 20%, and the effects of cutting parameters on cutting force, surface morphology, and tool wear were analyzed. The results showed that the three-dimensional cutting force initially increased and then decreased with the increase in cutting speed. In addition, the three-dimensional cutting force increased with the increase in cutting depth and feed rate. Under the same cutting parameters, the three-dimensional cutting force of 7050 aluminum alloy was in the following order: 20% pre-deformation > 10% pre-deformation > 15% pre-deformation. During high-speed cutting, different degrees of plowing, bulging, and sticky chips appeared on the machined surface, and the surface morphology of the 15% pre-deformed 7050 aluminum alloy was better than that of the other two pre-deformed 7050 aluminum alloys. During the high-speed cutting process, tool wear mainly occurred in the forms of collapse edge, adhesion, flaking, and breakage, and wear mechanisms were usually adhesive, diffusion, and oxidation wears. Under the same cutting parameters, the tool wear of the 15% pre-deformed 7050 aluminum alloy was lighter. Full article

Pes planus, colloquially known as flatfoot, is a deformity defined as the collapse, flattening or loss of the medial longitudinal arch of the foot. The first standard radiographic examination for diagnosing pes planus involves lateral and dorsoplantar weight-bearing radiographs. Recently, many artificial intelligence-based computer-aided diagnosis (CAD) systems and models have been developed for the detection of various diseases from radiological images. However, to the best of our knowledge, no model and system has been proposed in the literature for automated pes planus diagnosis using X-ray images. This study presents a novel deep learning-based model for automated pes planus diagnosis using X-ray images, a first in the literature. To perform this study, a new pes planus dataset consisting of weight-bearing X-ray images was collected and labeled by specialist radiologists. In the preprocessing stage, the number of X-ray images was augmented and then divided into 4 and 16 patches, respectively in a pyramidal fashion. Thus, a total of 21 images are obtained for each image, including 20 patches and one original image. These 21 images were then fed to the pre-trained MobileNetV2 and 21,000 features were extracted from the Logits layer. Among the extracted deep features, the most important 1312 features were selected using the proposed iterative ReliefF algorithm, and then classified with support vector machine (SVM). The proposed deep learning-based framework achieved 95.14% accuracy using 10-fold cross validation. The results demonstrate that our transfer learning-based model can be used as an auxiliary tool for diagnosing pes planus in clinical practice. Full article

Acoustic emissions (AEs) and weak electrical signals, also known as pressure stimulated currents (PSCs), were concurrently recorded in order to investigate their behavior and detect precursory indicators when cement mortar specimens were subjected to mechanical compressive loading, emphasizing the behavior of the AEs and the PSC signal in the vicinity of fracture. The axial compressive loading protocol incorporated a constantly increasing stress, from early stress values up to the vicinity of fracture and a sequential stress stabilization until the time the specimen collapses, due to severe growing internal damages. Concurrent recordings of the electrical and acoustic emissions were performed. The AE recordings were analyzed, by incorporating the recently introduced F- and P-functions, and the well-known b-value. The experimental results highlight strong similarities regarding the variations of the PSC signal, the AE hits occurrence rate (F-function), and the AE hits energy release rate (P-function). The above was also confirmed with another similar experiment in an identical specimen. It is noteworthy that, during the stay of the specimens under a constant load regime near their strength levels, a peak appears in the above quantities, which is directly related to an increased rate of axial deformation. The temporal evolution of the b-values is also presented. Results show that the local minima appearing at values close to b ≈ 1.0 correspond to the local maxima of the PSC signal. It is straightforwardly concluded that when both the PSC signal and the AE data are combined, they provide clear pre-failure indicators. Full article

Due to soil disturbance during the construction of metro stations, the initial stress of the stratum is modified, leading to ground settlement within a particular range, fracturing the surrounding buildings and even causing significant ground deformation and building collapse. This paper employed the Pile-Beam-Arch method to assemble the Daguanying Station of Beijing Metro Line 7 as the engineering background. The numerical calculation method was used to study the regulations of ground settlement and structural deformation throughout the construction stage. Meanwhile, the effect of surface loading was taken into account and surface settlement control strategies were suggested. Finally, the Stochastic medium theory was used to predict surface settlement. It was evident from the study’s findings that the pilot tunnels excavation and the arches installation accounted for 67% and 23.1% of the total surface settlement, respectively, and produced the most surface settlement. Surface settlement can be significantly reduced by utilizing grouting reinforcement technology and the pilot tunnels excavation approach of “upper first, then lower and side first, then middle”. The structure was much less stressed during the pre-construction stage, with the maximum principal stress ranging from 1 to 5 MPa; after construction was finalized, the maximum principal stress reached 14.203 MPa, concentrating mostly in the middle column part, which was the consequence of the combined action of the upper load and the lower soil uplift. Additionally, there was a linear relationship between the surface load and ground settlement. The bottom slab and the middle column were situated where the structure’s most unfavorable components were concentrated. The conclusions of the surface settlement prediction demonstrated that there were discrepancies between the theoretical calculation and the simulated; thus, the prediction results were more conservative. The study results can serve as a reference for construction sites. Full article

The study of geo-hydrological problems in urban contexts of considerable historical importance plays an extremely interesting role in the safeguarding of architectural and artistic assets of great value. The need to guarantee the conservation of monumental heritage is an ethical and moral requirement that new generations have a duty to support. Operating in urbanised contexts is extremely difficult, due to the presence of infrastructures and underground services that prevent the execution of classical surveys and prospecting. The technologies currently available, however, allow us to also investigate the subsoil in a non-destructive way and to control the evolution of active natural phenomena in a continuous and automated way with remote-sensing techniques. The methodological approach consists of the development of a series of cognitive investigations, aimed at identifying the elements of weakness of the soil system, so as to be able to subsequently undertake the most appropriate decisions for the reduction of geo-hydrological risks. The case here analysed concerns Lanciano city (Central Italy), famous for its pre-Roman origins, that was affected by a violent storm in the summer of 2018. This event devastated the inhabited Centre with flooding of all the neighbourhoods and the collapse of parts of buildings. For this reason, direct and indirect geognostic investigations were carried out within the Historical Centre, which is of considerable architectural value, and an important monitoring system was installed. The actual geo-hydrological hazard was planned using 3D numerical modelling to define the hydraulic and deformational behaviour of the subsoil. Comparison between the modelling performed and the monitoring data acquired has allowed us to understand the complex behaviour of the subsoil and the subsidence mechanisms of the Historic Centre. Full article

Beam-column joints constructed in the pre-seismic building code do not provide transverse reinforcement and good reinforcement detailing within the region. These cause the occurrence of brittle shear failure, which is one of the factors affecting the number of reinforced concrete (RC) moment resistance building structures collapsing during an earthquake. Therefore, in this study a brittle beam-column joint with a non-seismic building code was designed and strengthened by a ferrocement. Four layers of wire mesh with a diameter of 1 mm and a mesh size of 25.4 mm were installed on both sides of the beam-column joint and cement mortar was cast on it. As a comparison, a ductile beam-column joint was also designed following the current building code, which considers seismic effects. The test results by applying reversed cyclic loading at the beam tip showed that strengthening using ferrocement prevents crack propagation, increasing the deformation capacity, ductility, stiffness, and energy dissipation of beam column joint which are higher than those of the beam-column joint which is designed following the current building code. However, the strengthening does not improve the load carrying capacity significantly. Full article

The 22 August 1902 Mw 7.7 Atushi earthquake is the most disastrous seismic event in the southwestern Tian Shan. However, the spatial distribution of surface rupture zones as well as the geometric feature of surface deformation remain unclear, and the seismogenic fault is still controversial. Based on geologic and geomorphic interpretations of multiple remote sensing imaging data, high-resolution DEM data derived from UAV imaging complemented by field investigations, we mapped two sub-parallel NEE-trending surface rupture zones with a total length of 108 km. In addition, ~60 km and ~48 km surface rupture zones are distributed along the pre-existing Atushi fault (ATF) and the Keketamu fault (KTF), respectively. The surface deformations are mainly characterized as bedrock scarp, hanging wall collapse scarp, pressure ridge, and thrust-related fold scarps along the two south-dipping thrust faults, which are defined as the seismogenic structure of the 1902 Mw 7.7 Atushi earthquake. Thus, we proposed the cascading-rupture model to explain the multiple rupture zones generated by the 1902 Mw 7.7 Atushi earthquake. Moreover, the multiple advanced remote sensing mapping techniques can provide a promising approach to recover the geometric and geomorphic features of the surface deformation caused by large seismic events in the arid and semi-arid regions. Full article

In this study, the effect of an ultrasound (US) pre-treatment on the process of drying Cistanche slices through far-infrared vacuum drying was investigated with various experimental factors, including the US treatment time (25, 35, 45 min), frequency (20, 40, 60 kHz) and power (150, 180, 210 W). The results showed that compared with the samples without US, the material drying time after the US treatment was reduced by 16–36.8%. The effective moisture diffusion coefficients of Cistanche slices under different US conditions ranged from 1.61122 × 10⁻⁸ to 2.39274 × 10⁻⁸ m²/s, which agreed with food processing ranges. In addition, the phenylethanoid glycoside, iridoid, polysaccharide, total phenol and total flavonoid contents in Cistanche were significantly increased after US pre-treatment. However, the dried products obtained with the 45 min US treatment had greatly damaged internal structures, collapsed and seriously deformed surfaces, and low contents of active ingredients. Overall, the US pre-treatment could significantly improve the drying quality of Cistanche slices. Full article

The paper presents the developed fiber-optic sensors for monitoring pressure measurement on the elements of mine supports. The sudden destruction of the support leads to the collapse of the mine workings and poses a serious threat to the life and safety of underground workers. A fiber-optic system for monitoring changes in pressures on the elements of mine supports will increase the share of mining automation and reduce the share of manual labor, as well as eliminate measurement errors associated with the human factor. Systematic monitoring of the state of the working elements of the support will allow timely tracking of their deformations caused by an increase in rock pressure on them. Implementation of the system at mining enterprises will expand the use of digital technologies in mining. Timely warning of a mine collapse threat will significantly increase the level of safe mining operations, as well as reduce the cost of supporting mine workings, since elimination of the consequences of destruction is associated with significant material costs. This work presents a developed laboratory testbench that simulates a mine working and elements of an arch support on which are installed the fiber-optic sensors connected to an automated measuring system. The developed hardware and software complex provides the processing of a light spot falling on the surface of a television matrix that is installed at the exit from the optical fiber. The results of visual processing are converted into numerical values, which are used to make a decision about the state of the considered object. In addition to automatic monitoring of the structural integrity condition of the considered object, the system is equipped with a function of a visual display for monitoring results, which makes it possible to track sharp fluctuations and bursts of pressure parameters, based on which the prediction of pre-emergency and emergency situations is performed. Full article