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Monitoring the stress of steel strands, from initial tension to eventual failure, is paramount for assessing structural safety and understanding its failure mechanism. Current monitoring methods are restricted in measuring stress only until yielding because of their limited range. This study proposes a novel coaxial strain-sensing cable (CSSC) based intelligent steel strand (CSSC-ISS), which has both functions of force-bearing and self-sensing. First, the prototype design of CSSC-ISS and the sensing principle of CSSC are introduced. Then, a fabrication method of small-diameter CSSC is proposed, which is then encapsulated with glass fiber reinforced polymer (GFRP) material, forming a GFRP sensing rod (GFRP-SR). The next step involves replacing the strand’s central wire with the GFRP-SR, culminating in the creation of the CSSC-ISS. Finally, Laboratory tests show that the CSSC has excellent strain-sensing performance with a resolution of at least 100 µε and a measurement range of 150,000 µε. The GFRP-SR offers good sensing potential and comparable mechanical strength to standard GFRP rods. Notably, the CSSC-ISS could measure stress up to strand failure, retaining 87.9% tensile strength and 88.7% elastic modulus compared to standard steel strands. It is verified that the CSSC-ISS can consistently measure its stress condition throughout its life cycle without compromising its load-bearing potential.

Ice avalanche (IA) has a strong concealment and sudden characteristics, which can cause severe disasters. The early identification of IA hidden danger is of great value for disaster prevention and mitigation. However, it is very difficult, and there is poor efficiency in identifying it by site investigation or manual remote sensing. So, an artificial intelligence method for the identification of IA hidden dangers using a deep learning model has been proposed, with the glacier area of the Yarlung Tsangpo River Gorge in Nyingchi selected for identification and validation. First, through engineering geological investigations, three key identification indices for IA hidden dangers are established, glacier source, slope angle, and cracks. Sentinel-2A satellite data, Google Earth, and ArcGIS are used to extract these indices and construct a feature dataset for the study and validation area. Next, key performance metrics, such as training accuracy, validation accuracy, test accuracy, and loss rates, are compared to assess the performance of the ResNet50 (Residual Neural Network 50) and VGG16 (Visual Geometry Group 16) models. The VGG16 model (96.09% training accuracy) is selected and optimized, using Early Stopping (ES) to prevent overfitting and L2 regularization techniques (L2) to add weight penalties, which constrained model complexity and enhanced simplicity and generalization, ultimately developing the ES-L2-VGG16 (Early Stopping—L2 Norm Regularization Techniques—Visual Geometry Group 16) model (98.61% training accuracy). Lastly, during the validation phase, the model is applied to the Yarlung Tsangpo River Gorge glacier area on the Tibetan Plateau (TP), identifying a total of 100 IA hidden danger areas, with average slopes ranging between 34° and 48°. The ES-L2-VGG16 model achieves an accuracy of 96% in identifying these hidden danger areas, ensuring the precise identification of IA dangers. This study offers a new intelligent technical method for identifying IA hidden danger, with clear advantages and promising application prospects. [ABSTRACT FROM AUTHOR]

To explore the axial compressive mechanical properties of steel tube recycled steel fiber reinforced concrete short columns (STRSFRCSCs), axial compression tests were conducted on ten STRSFRCSCs and two steel tube reinforced concrete short columns (STRCSCs), mainly analyzing the effects of recycled steel fiber (RSF) content, steel content, and concrete strength grade on their mechanical properties. The results showed that different RSF contents had no significant effect on the failure mode of the specimens, while the concrete strength grade and steel content had a significant effect on the failure mode. When the steel content was 2.84%, the specimens experienced shear failure, while when the steel content was 4.24%, they experienced waist drum failure. As the RSF content increased, the peak strain during the loading process of the specimens decreased, and the transverse deformation coefficient at the peak decreased. The addition of RSF significantly improved the ductility performance of the specimens. When the volume fraction of RSF was 2%, the bearing capacity of the specimens increased the most, reaching 13.4%, and the ductility coefficient gradually increased. The axial compressive bearing capacity and combined elastic modulus of the specimens increased with the increase in concrete strength grade, RSF content, and steel content. [ABSTRACT FROM AUTHOR]

Reservoir impoundment induces a large amount of cumulative deformation of landslide body, leading to damage to the geological environment. Due to many yearly cycles of reservoir water fluctuation, the cumulative deformation of landslides tends to be stable, showing a self-adaptive deformation phenomenon. The study of the self-adaptive deformation mechanism is very important for evaluating landslide stability and achieving the safe operation of hydropower stations. To study the mechanism of self-adaptive deformation, two sets of physical models were used to monitor the groundwater, earth pressure, and cumulative deformation of landslide under periodic fluctuations of the reservoir water level. The results showed that the soil consolidation compaction, release of sliding stress, and increase in permeability are the three main factors of the self-adaptive deformation of landslide accumulation. The overall permeability decreased first and then increased, the front permeability increased greatly, and the middle and rear permeability decreased. The main factors that affected the permeability change were deformation and seepage force. [ABSTRACT FROM AUTHOR]

The characteristics and hysteresis of seepage are critical for assessing the stability of creeping soil landslides after reservoir impoundment. First, field and laboratory tests were conducted to obtain the saturated permeability coefficient of 396 soil landslides within the Three Gorges Reservoir area and trends among these results were obtained through basic statistics. Second, geological surveys show that these soil landslides are mainly composed of mixed soil-rock structures. Thus, a pressure plate instrument was used for estimating the soil-water characteristic parameters of this unsaturated soil-rock mixture. Finally, the seepage characteristics and hysteresis of the soil landslides was analyzed through numerical simulation based on obtained permeability parameters. The results of this research show that the permeability level of the soil landslides in the Three Gorges Reservoir Area is, in overall terms, good and moderate, and the permeability of the soil landslides has certain spatial distribution characteristics. Also, it was found that the parameters a and m of the unsaturated Fredlund-Xing model became larger with increasing gravel particle size, dry density, and plasticity index of the soil particle; all with decreasing gravel content. Behavior of the n parameter shows an opposite trend. Furthermore, more than 90% of landslides show seepage hysteresis as their hysteresis parameter is less than 35. Finally, it was found that the hysteresis coefficient and slope gradient are the key parameters conditioning the hysteresis of soil landslides.

Rainfall is the main factor influencing the stability of landslides, but the precise mechanisms and processes are still poorly known. Unsaturated soil mechanics can be used to study how suction and temporary pore water pressure affect landslide stability. During rainfall, the groundwater level in the landslide will change, and the suction and temporary pore water pressure will also change with time and rainfall. Construction of a field observation well is an effective method of studying changes in suction. An observation well was constructed in an ancient landslide in the Three Gorges reservoir area in China. The well has a depth of 20 m, a diameter of 2 m, and is the largest observation well for monitoring of suction and temporary water pressure in the world. Suction, temporary water pressure, and rainfall were measured between October 2002 and December 2004; this is the longest observation period for this type of study. Analysis of the results shows that the distribution of suction is determined by the depth, soil materials, gradation, and structure of the landslide. The changes in suction are related to the intensity and duration time of rainfall, the season, and the climate. If the suction does not change promptly after rain, there is a time difference between the timing of rainfall and of suction change. The suction varied between 0 and 15 kPa. These conclusions form a basis for further scientific studies on how rainfall affects landslides. [ABSTRACT FROM AUTHOR]

Hydrate (shorted for natural gas hydrate) is one of the most promising future energies, and dissociating hydrate in situ is commonly recognized as the best strategy to realize commercial exploitation. So it is significant to understand the fundamental mechanism in the process of hydrate dissociation involving complicated thermal-hydraulic-mechanical-chemical phenomena. To date, the multiphysical evolution patterns are not revealed by the overall comparison among different phenomena, and we still have little knowledge on the contributions of different influence factors to hydrate dissociation rate. More importantly, the fundamental study has a considerable gap to the real engineering. Therefore, in this paper, a fully-coupled thermal-hydraulic-mechanical-chemical model is developed to further analyze the evolution of all phenomena from both global and local perspectives and find the coupled relationships among physical/chemical phenomena from a dynamic competition perspective. Results show that the global spatial distributions of pressure, hydrate saturation and strain show one simple pattern during hydrate dissociation，while those of temperature and hydrate dissociation rate manifest four and three complex patterns respectively. The effective hydrate reaction specific area, reaction coefficient and pressure difference play different roles in the domination of the trend and value of hydrate dissociation rate. Additionally, two examples are given to demonstrate the implications of the fundamental mechanism to the engineering. A negative-power-law relation is found between the finish time of hydrate dissociation and the heat transfer coefficient of outside heat source (geothermal heat in real engineering). A good linear relation between hydrate dissociation front and pressure transfer front is found, which provides a possible easy way to predict the range of dissociated hydrate by pressure in the real engineering. • Multiphysical evolution patterns are comprehensively revealed. • Roles of influence factors of hydrate dissociation rate are clarified. • A negative-power-law relation is found between finish time of hydrate dissociation and outside heat transfer coefficient. • An easy way is suggested to predict the range of dissociated hydrate by pressure for the real engineering. [ABSTRACT FROM AUTHOR]

Tetrachloroethene (PCE), trichloroethene (TCE) and carbon tetrachloride (CT) were selected as target contaminants in this paper. Experiments were conducted to determine the effectiveness of zero-valent iron on dechlorination reaction and reaction-affecting factors in different mixing conditions. The results show that selected iron scrapes were effective in the dechlorination of chlorinated aliphatics, especially for chlorinated alkanes, and dechlorination reaction was pseudo first order. When PCE and TCE coexist, the reaction rate constant (K) was 0.0624 mL.(m2.h)-1 and 0.0357 mL.(m2.h)-1 respectively, showing the higher the chlorinated degree the quicker the reaction. When CT and PCE coexist, K was 0.1341 mL.(m2.h)-1 and 0.0129 mL.(m2.h)-1 respectively; compared with PCE, CT was degraded much more quickly and thoroughly giving an account of alkane was prior to alkene in dechlorination when at the same chlorinated degree. Either chlorinated alkanes or alkenes, their degradation half-lives were lower in monocomponent condition than coexisting with other component.