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Objective With the rapid increase in construction projects in the western regions in recent years, the impact of seasonal freeze-thaw cycles in the high-altitude areas of western China has become more pronounced. Conducting research on the microscopic characteristics and strength degradation properties of rocks under freeze-thaw cycles is crucial for guiding engineering construction in these cold, high-altitude regions. Methods To study the influence of freeze-thaw cycles on rock structure and mechanical properties, we collected diorite samples from a tunnel in the Kangding area and examined the effects of freeze-thaw cycles on their microstructure and mechanical characteristics. Firstly, thin rock sections were observed under a polarizing microscope to obtain mineral compositions and microstructures. Then, CT scanning technology was used to scan the granite samples after freeze-thaw cycles, and the scanned layers were binarized using threshold segmentation. The scanning images of different layers were binarized using threshold segmentation, and high-resolution 3D data and images of the internal and external structures of the samples were obtained by stacking the binary image layers. Fractal theory was applied to calculate the box-counting dimension of the images and quantitatively assess their complexity. This analysis allowed us to examine the evolution and distribution characteristics of the internal structure of granite under freeze-thaw cycles. Results Under a polarizing microscope, the rock exhibits a block-like structure with a patchy, coarse-grained, and unequal-grained granite texture, with locally visible metasomatic worm structures. The main phenocryst minerals are alkaline feldspar. Other minerals range in size from 0.25 to 4.0 mm and primarily include quartz, plagioclase, and alkaline feldspar. Secondary minerals include biotite and epidote, while accessory minerals comprise apatite, zircon, and pyrite. Microscopically, the rock is identified as porphyritic, coarse-grained, and unequal-grained biotite diorite granite. Freeze-thaw cycles were applied to the granite samples in the laboratory to study the strength evolution and explore the relationship between structural evolution and strength. The results indicate that the freeze-thaw cycle effect leads to an overall increase in the internal porosity of the granite's microstructure, though the rock's permeability changes minimally, with an increase of only 0.003×10−3 μm2. The internal pore development is uneven, primarily due to the emergence of new micropores, causing changes in the overall structure of the sample. After freeze-thaw cycles, the complexity of the internal structure of the rock decreases, but the overall integrity remains good, with the fractal dimension staying at a high level. Fractal analysis shows that 20 freeze-thaw cycles do not cause significant changes in the structural complexity of granite. However, the overall mechanical properties of the sample decline, viscosity increases, and long-term strength shows significant attenuation, raising the strain threshold for entering the creep test stage. Conclusion When evaluating the safety of rocks with dense primary structures, considering only their structure may lead to deviations from the actual situation. It is essential to combine necessary strength indicators for a comprehensive evaluation. After undergoing freeze-thaw cycles, rocks tend to exhibit more significant deformation while maintaining lower strength. Therefore, appropriate treatments are required for construction in high-altitude areas. [ Significance ] This study provides a reference for applying fractal theory to the evolution of rock microstructure and the relationship between rock microstructure and strength evolution. It also offers valuable guidance for engineering construction in high-altitude and cold regions.

The pile-beam composite structure in high-elevation debris flow areas is selected as the research object. Based on characterizing the pile-beam composite structure, the particle-flow simulation analysis program and the explicit dynamic analysis program were used to study comparatively the blocking effects of single-row piles and two-row piles, as well as that of a pile-beam composite structure at different positions. Besides, We simulated the mechanical characteristics of the pile-beam composite structure and discussed debris flow accumulation and structural stress transfer after the blocking. The calculation results show that the blocking effect of the pile-boulder force chain formed by the contact between large-size particles in the debris flow with the blocking structure and side boundaries on both sides of the gully could effectively block and delay the subsequent debris flow movement. The blocking effect of the pile-beam composite structure is the best. Meanwhile, the transition zone between the two-row piles further suppressed the flow velocity. When choosing the position for a pile-beam composite structure, we should consider suppressing the debris flow velocity as early as possible at the beginning and the potential energy-kinetic energy conversion process. Meanwhile, we also need to emphasize the design of the reservoir capacity, beware of the escape of debris flow due to a low-head barrier, and choose the optimal solution for the layout. The impact stress by debris flow boulders will be transmitted to the rear pile through the connecting beams, and the connecting parts at both ends of the beam almost reach the yield strength, which needs reinforcement to strengthen.

In order to evaluate the zoning and risk of debris flow gully based on numerical simulation, a set of theoretical system and technical process of debris flow quantitative risk analysis suitable for mountainous towns in southwest China was constructed, taking buildings and roads as the research objects, in view of the particularity of disaster-bearing body types and debris flow disaster modes. It is mainly divided into three steps: (1) Using FLO-2D numerical model, the risk of debris flow is expressed by intensity index IDF; The simulation results of debris flow in Gully A 7·11 show that the area of correctly judged area is 50.02×104m2, the comprehensive accuracy index ω is 1.22, and the maximum IDF can reach 1013.25m3/s2, showing a general trend that the upstream is higher than the downstream, and the center of the drainage channel is higher than both sides. Using the data of debris flow damage in A ditch 7·11 in A city, a material vulnerability curve based on the probability of exceeding loss is constructed. Based on the establishment of disaster-bearing body database, the expected loss of disaster-bearing body can be expressed quantitatively by setting different future debris flow scenarios. The model verification and case application of A ditch in A city show that the quantitative risk analysis system of debris flow can well reflect the response mechanism of disaster-bearing body and debris flow, and can provide scientific basis for disaster prevention and mitigation in debris flow threat areas.

Purple soil is rich in semiconducting minerals, but the impact of these minerals on soil properties and associated microbiome assemblages has received little attention. To better understand the influence of semiconducting minerals in soils, samples were collected from 4 soil classifications, including purple soil, siltstone, farmland, and new formed soil. Goethite was the main semiconducting mineral in purple soil followed by rutile and birnessite, while for siltstone, rutile was the major semiconducting mineral. Proteobacteria (77.77–98.56%) was the most prevalent phylum among all samples, with the second most abundant phylum being Cyanobacteria (purple soil and farmland) and Firmicutes (siltstone and new formed soil). According to the average path length in network analysis, purple soil showed higher species segregation, which suggested purple soil was potentially more susceptible to external interference than the other types. The relationship between microbes may be synergistic due to the positive links between microbial phyla. Rutile affected microbial composition to the greatest extent, accounting for 13.66% of the total variation in microbial assembly, while goethite (r= –0.0947) and birnessite (r = 0.0215) content were also associated with changes in microbial composition. These results demonstrated that semiconducting minerals affected the structure and potential energy utilization of soil microbial communities. [ABSTRACT FROM AUTHOR]

On December 18, 2023, an Ms 6.2earthquake occurred in Jishishan County, Linxia Prefecture, Gansu Province, causing a large number of geological disasters and threatening people's lives and the safety of infrastructure. After the earthquake, Gansu and Qinghai provincial governments quickly deployed hundreds of geology professionals to carried out the investigation and verification geological disasters in the earthquake area. Based on the results of the earthquake geohazard investigation and verification, this paper analyses the characteristics, control factors and development trend of the earthquake-induced geohazards, and puts forward suggestions on disaster prevention and risk mitigation measures. Till December 23, a total of 2044 geohazards have been checked, including 78 new geohazards, 88 existing geohazards with intensified deformation due to earthquake, and 1 878 existing geohazards without obvious different from before. Most of new and intensified deforming geohazards are collapse, accounting for 67.5%, followed by landslide, accounting for 31.9%. Most of new and intensified deforming geohazards are small in scale, accounting for 84.9%, followed by medium, accounting for 10.8%. Disaster mode of new and intensified deforming geohazards are mostly small collapse threatening houses and roads. The co-seismic geohazards are densely distributed along the seismic fault, and the spatial density increases with the enhancement of earthquake intensity. Data from 206 groups of accelerate-meters within 50 km from the epicenter of the National Geological Safety Monitoring Network showed that the peak acceleration of the earthquake area was 30.4-1969.7 mg. and decayed logarithm with the increase of the distance from the epicenter. In addition, the surface deformation monitoring equipment also recorded the co-seismic displacement curve of a typical landslide. Analysis shows, earthquake put a deteriorate effect to rock and soil, which decreased their integration and strength. There is a magnificent geohazard after-effect of earthquake; collapse, landslide and debris flow will be much often than before. So the authors suggest: (1) update earthquake geohazard database as soon as possible, (2) work out targeted prevention and control measures for the geohazards with large potential danger, (3) conduct comprehensive remote sensing monitoring and research of earthquake-induced geohazard mechanism, (4) improve the meteorological early warning model and threshold. By all this efforts the risk of geohazards after earthquake will be reduced and controlled. [ABSTRACT FROM AUTHOR]

[Objective] With the rapid increase in construction projects in the western regions in recent years, the impact of seasonal freeze-thaw cycles in the high-altitude areas of western China has become more pronounced. Conducting research on the microscopic characteristics and strength degradation properties of rocks under freeze-thaw cycles is crucial for guiding engineering construction in these cold, high-altitude regions. [Methods] To study the influence of freeze-thaw cycles on rock structure and mechanical properties, we collected diorite samples from a tunnel in the Kangding area and examined the effects of freeze-thaw cycles on their microstructure and mechanical characteristics. Firstly, thin rock sections were observed under a polarizing microscope to obtain mineral compositions and microstructures. Then, CT scanning technology was used to scan the granite samples after freeze-thaw cycles, and the scanned layers were binarized using threshold segmentation. The scanning images of different layers were binarized using threshold segmentation, and highresolution 3D data and images of the internal and external structures of the samples were obtained by stacking the binary image layers. Fractal theory was applied to calculate the box-counting dimension of the images and quantitatively assess their complexity. This analysis allowed us to examine the evolution and distribution characteristics of the internal structure of granite under freeze-thaw cycles. [Results] Under a polarizing microscope' the rock exhibits a block-like structure with a patchy, coarse-grained, and unequal-grained granite texture, with locally visible metasomatic worm structures. The main phenocryst minerals are alkaline feldspar. Other minerals range in size from 0.25 to 4.0 mm and primarily include quartz, plagioclase, and alkaline feldspar. Secondary minerals include biotite and epidote, while accessory minerals comprise apatite, zircon, and pyrite. Microscopically, the rock is identified as porphyritic, coarse-grained, and unequal-grained biotite diorite granite. Freeze-thaw cycles were applied to the granite samples in the laboratory to study the strength evolution and explore the relationship between structural evolution and strength. The results indicate that the freeze-thaw cycle effect leads to an overall increase in the internal porosity of the granite's microstructure, though the rock's permeability changes minimally, with an increase of only 0.003x10-3 µm² The internal pore development is uneven, primarily due to the emergence of new micropores, causing changes in the overall structure of the sample. After freeze-thaw cycles, the complexity of the internal structure of the rock decreases, but the overall integrity remains good, with the fractal dimension staying at a high level. Fractal analysis shows that 20 freeze-thaw cycles do not cause significant changes in the structural complexity of granite. However, the overall mechanical properties of the sample decline, viscosity increases, and long-term strength shows significant attenuation, raising the strain threshold for entering the creep test stage. [Conclusion] When evaluating the safety of rocks with dense primary structures, considering only their structure may lead to deviations from the actual situation. It is essential to combine necessary strength indicators for a comprehensive evaluation. After undergoing freeze-thaw cycles, rocks tend to exhibit more significant deformation while maintaining lower strength. Therefore, appropriate treatments are required for construction in high-altitude areas. [Significance] This study provides a reference for applying fractal theory to the evolution of rock microstructure and the relationship between rock microstructure and strength evolution. It also offers valuable guidance for engineering construction in high-altitude and cold regions. [ABSTRACT FROM AUTHOR]

Since the quality of steel is of paramount importance in modern production, the defects detection of steel surface is significantly crucial. In this field, two‐stage detection algorithms have encountered issues about low detection speed, while one‐stage detection algorithms have room for improvement in detection accuracy. How to trade‐off between accuracy and speed of detection to better meet the demands of industrial production remains a challenge. To address this problem, this paper proposes a You Only Look Once version 5 (YOLOv5)‐based improved method ACD‐YOLO. ACD‐YOLO model incorporates anchors optimization, context augmentation module, and efficient convolution operators. In anchor optimization, the boundaries of anchors are optimized using an improved genetic algorithm. Moreover, to improve detection accuracy, a context augmentation module is incorporated into both the head and the backbone end of the network. Additionally, efficient convolution operators are adopted to address the increase of computation complexity caused by the context augmentation module. Experimental results show that ACD‐YOLO achieves mean average precision of 79.3%, with frames per second of 72. Compared to reference methods, ACD‐YOLO achieves the best balance between accuracy and speed of detection, and is more suitable for practice industrial production. [ABSTRACT FROM AUTHOR]

Semiconductor minerals in peatland play a significant role in the stability of the soil carbon pool. Nevertheless, the ecosystem‐scale importance of semiconductor minerals distribution and their influence on carbon stability in peatlands is still to be determined. Therefore, this study investigated the spatial distribution of semiconductor minerals and their photoelectrochemical activity (PA) in three peatlands with distinct water tables (Equisetum‐swamp [−2.0 cm], Caltha‐meadow [−8.0 cm], and Carex‐meadow [−13.8 cm]). The results indicate that the peatlands of the Qinghai‐Tibet Plateau mainly contain hematite (4.64 wt%), brookite (0.71 wt%), baddeleyite (0.23 wt‰), and zincite (0.10 wt‰); hematite content is the main mineral in peatland. And significantly increased with the decrease of the water table; the photoelectrochemical examination showed that the band gap of semiconductor minerals displayed Caltha‐meadow > Equisetum‐swamp > Carex‐meadow, and the carrier concentration displayed Carex‐meadow > Equisetum‐swamp > Caltha‐meadow, and Carex‐meadow exhibits a steady photocurrent density (0.3 μA/cm2) under light. This suggests that peat soils exhibit an improved photoelectric response with water table drawdown, which would promote the potential for soil carbon mineralization; structural equation model analysis showed that hematite had a significant positive effect on soil organic carbon (SOC), while the PA of semiconductor minerals had a significant negative effect on SOC. That is, semiconductor minerals can not only protect SOC by adsorption but also accelerate organic carbon mineralization by photo‐catalytic generation of reactive oxygen species. Therefore, the decrease in the water table increases the PA of semiconductor minerals, which will weaken the protective effect of semiconductor minerals on soil carbon through adsorption and other means. [ABSTRACT FROM AUTHOR]