Search Results (134)

This paper discusses the integrated technology of CO₂ adsorption and catalysis, which combines adsorption and catalytic conversion, simplifies the traditional process, reduces energy consumption, and improves efficiency. The traditional carbon capture technology has the problems of high energy consumption, equipment corrosion, and absorbent loss, while the integrated technology realizes the adsorption, conversion, and catalyst regeneration of CO₂ in a single reaction system, avoiding complex desorption steps. Through micropore confinement and surface electron transfer mechanism, the technology improves the reactant concentration and mass transfer efficiency, reduces the activation energy, and realizes the low-temperature and high-efficiency conversion of CO₂. In terms of materials, MOF-based composites, alkali metal modified oxides, and carbon-based hybrid materials show excellent performance, helping to efficiently adsorb and transform CO₂. However, the design and engineering of reactors still face challenges, such as the development of new moving bed reactors. This technology provides a new idea for CO₂ capture and resource utilization and has important environmental significance and broad application prospects. Full article

In-situ chemical oxidation (ISCO) is a common method to remediate chlorinated ethene contaminants in groundwater. Monitoring the effectiveness of ISCO can be hindered because of insufficient observations to assess oxidant delivery. Advantageously, potassium permanganate, one type of oxidant, provides the opportunity to use its strong electrical signal as a surrogate to track oxidant delivery using time-series borehole geophysical methods, like electromagnetic (EM) induction logging. Here we report a passive ISCO (P-ISCO) experiment, using potassium permanganate cylinders emplaced in boreholes, at a chlorinated ethene contamination site, Naval Air Station Pensacola, Florida. The contaminants are found primarily at the base of a shallow sandy aquifer in contact with an underlying silty-clay confining bed. We used results of the time-series borehole logging collected between 2017 and 2022 in 4 monitoring wells to track oxidant delivery. The EM-induction logs from the monitoring wells showed an increase in EM response primarily along the contact, likely from pooling of the oxidant, during P-ISCO treatment in 2021. Interestingly, concurrent natural gamma-ray (NGR) logging showed a decrease in NGR response at 3 of the 4 wells possibly from the formation of manganese precipitates coating sediments. The coupling of time-series logging and well-chemistry data allowed for an improved assessment of passive ISCO treatment effectiveness. Full article

With the further implementation and development of the Western Development Strategy, studying the mechanical behavior and deformation characteristics of deep-buried tunnels in layered hard rock under high ground stress conditions holds considerable engineering significance. To study the mechanical properties and long-term deformation and failure characteristics of different bedding stratified rocks, this research employed an MTS815 electro-hydraulic servo rock testing system and a French TOP rheometer. Triaxial compression tests, rheological property tests, and long-term cyclic and unloading tests were conducted on shale samples under varying confining pressures and bedding angles. The results indicate that (1) under triaxial compression, shale demonstrates pronounced anisotropic behavior. When the confining pressure is constant, the peak strength of the rock sample exhibits a “U”-shaped variation with the bedding angle (its minimum value at 60°). For a fixed bedding angle, the peak strength of the rock sample progressively increases as the confining pressure rises. (2) The mode of shale failure varies with the angle: at 0°, shale exhibits conjugate shear failure; at 30°, shear slip failure along the bedding is controlled by the bedding weak plane; at 60° and 90°, failure occurs through the bedding. (3) During the creep process of layered shale, brittle failure characteristics are evident, with microcracks within the sample gradually failing at stress concentration points. The decelerated and stable creep stages are prominent; while the accelerated creep stage is less noticeable, the creep rate increases with increasing stress level. (4) Under low confining pressure, the peak strength during cyclic loading and unloading creep processes is lower than that of conventional triaxial tests when the bedding plane dip angles are 0° and 30°, which is the opposite at 60° and 90°. (5) In the cyclic loading and unloading process, Poisson’s ratio gradually increases, whereas the elastic modulus, shear modulus, and bulk modulus gradually decrease. Full article

This study focuses on Neogene red-bed soft rock tunnels in the Huicheng Basin, China. Through engineering geological investigation, remote wireless monitoring systems, and total station multi-parameter monitoring, the deformation characteristics of red-bed soft rock surrounding rock under high in situ stress environments and their influencing factors were systematically analyzed. The findings reveal that the surrounding rock deformation follows a three-stage evolutionary pattern of “rapid, slow, and stable”. Construction disturbances can disrupt the stable state, leading to “deep V-shaped” anomalies or double-step responses in deformation curves. Spatially, the deformation exhibits significant anisotropy, with the haunch area showing the maximum deformation (95 mm) and the vault the minimum (65–73 mm). Deformation stabilization requires 30–42 days, and a reserved deformation of 10 cm is recommended based on specifications. Mechanical behavior analysis indicates that the stress–strain curves of red-bed argillaceous sandstone are stepped, with increased confining pressure enhancing both peak and residual strengths, validating the necessity of timely support. The study elucidates a multi-factor coupling mechanism: rock mass classification, temporal–spatial effects (excavation face constraints and rheological properties), construction methods, in situ stress levels, and support timing (timely support during the rapid phase inhibits strength degradation) significantly influence deformation evolution. The spatiotemporal distribution of surrounding rock pressure shows that invert pressure increases most rapidly, while vault pressure reaches the highest magnitude, with construction disturbances triggering stress redistribution. This research provides theoretical and practical guidance for the design, construction optimization, and disaster prevention of red-bed soft rock tunnels. Full article

The dislocation of the active fault zone altered the stress distribution and geometry of the track structure in the tunnel, which in turn affected the safety and stability of the train operation. Polyurethane-solidified track bed (PSTB) is suitable for sections crossing through active fault zones due to its excellent serviceability and adaptability to deformation. In this study, the stress and deformation response induced by active fault dislocation are investigated for this novel track structure. The corresponding deformation of track structure is subsequently introduced into a vehicle-track dynamics model to calculate the train operation safety index. The study examines the impact of fault displacement on railway track structures, revealing significant vertical deformation in rails that corresponds to the displacement magnitude. The effects are mainly confined to the active fault zone and its immediate surroundings, with variations depending on the fault zone’s structural characteristics. Key factors such as larger displacements, steeper fault angles, and narrower fault zones increase stress on track components, particularly the wide sleeper, which is prone to cracking and represents a structural vulnerability. Higher fault displacement, narrower zones, steeper angles, and increased train speeds elevate derailment risks and wheel load reduction rates, potentially exceeding safety limits. To ensure safety under typical fault conditions, train speeds should not exceed 250 km/h for PSTB with a 40 mm displacement and a 60° fault angle. These findings provide critical guidance for railway construction in fault-prone areas. Full article

The dairy sector plays a fundamental role in the economic development of numerous regions by creating jobs and sustaining the livelihoods of millions of people. However, concerns related to animal welfare and environmental sustainability—particularly greenhouse gas (GHG) emissions—persist in intensive dairy systems. This study aimed to measure and assess the presence of GHGs, such as methane (CH₄) and carbon dioxide (CO₂), in a compost barn facility, using spatial variability tools to analyze the distribution of these gasses at different heights (0.25 m and 1.5 m) relative to the animals’ bedding. Data were collected over five consecutive days using a prototype equipped with low-cost sensors. Geostatistical analysis was performed using R, and spatial distribution maps were generated with Surfer 13^®. Results showed elevated CH₄ concentrations at 0.25 m, exceeding values typically reported for similar systems values (60–117 ppm), while CO₂ concentrations remained within the expected range (970–1480 ppm), suggesting low risk to animals, workers, and the environment. The findings highlight the importance of continuous environmental monitoring to promote sustainability and productivity in confined dairy operations. Full article

The experimental study of shale fracture development is very important. As a channel of permeability, a fracture has a great influence on the development of shale gas. This study presents the results of a fracture evaluation in the Silurian Longmaxi Shale using the laboratory triaxial compression experiments and CT reconstruction, considering both mechanical properties and fracture network multi-dimensional quantitative characterization. The results indicate that the plastic deformation stage of shale lasts longer under high confining pressure, whereas radial deformation is restricted. Confining pressure has a nice linear connection with both compressive strength and elastic modulus. The 2D fractal dimension of radial and vertical cracks is 1.09–1.28 when the confining pressure is between 5 and 25 MPa. The 3D fractal dimension of the fracture is 2.08–2.16. There is a linear negative correlation at high confining pressure (R² > 0.80) and a weak linear association between the 3D fractal dimension of the fracture and confining pressure at low confining pressure. The fracture angle calculated by the volume weight of multiple main cracks has a linear relationship with the confining pressure (R² > 0.89), and its value is 73.90°–52.76°. The fracture rupture rate and fracture complexity coefficient are linearly negatively correlated with confining pressure (R² > 0.82). The Euler number can well characterize the connectivity of shale fractures, and the two show a strong linear positive correlation (R² = 0.98). We suggest that the bedding plane gap compression, radial deformation limitation, and interlayer effect weakening are efficient mechanisms for the formation of shale fracture networks induced by confining pressure, and that confining pressure plays a significant role in limiting and weakening the development of shale fractures, based on the quantitative characterization results of fractures. Full article

The inherent mineralogical alignment in stratified rock formations engenders pronounced mechanical anisotropy, presenting persistent challenges across geological, geotechnical, and petroleum engineering disciplines. While substantial progress has been made in modeling transversely isotropic media, current methodologies exhibit limitations in reconciling theoretical predictions with complex failure mechanisms. This investigation examines the anisotropic response of diverse lithologies through triaxial testing across bedding orientations (0–90°) and confinement levels (0–60 MPa), revealing a pressure-dependent attenuation of directional strength variations. Experimental evidence identifies three dominant failure modes: cross-bedding shear fracturing, bedding-parallel sliding, and hybrid mechanisms combining both, with transition thresholds governed by confinement intensity and bedding angle. Analytical comparisons demonstrate that conventional single weakness plane models produce characteristic shoulder-shaped strength curves with overpredictions, particularly in hybrid failure regimes. Conversely, the modified patchy weakness plane formulation achieves superior predictive accuracy through parametric representation of anisotropy gradation, effectively capturing strength transitions between end-member failure modes. The Pariseau criterion, though marginally less precise in absolute terms, provides critical insights into directional strength contrasts through its explicit differentiation of vertical versus parallel bedding responses. These findings advance the fundamental understanding of anisotropic rock behavior while establishing practical frameworks for optimizing stability assessments in bedded formations, particularly in high-confinement environments characteristic of deep reservoirs and engineered underground structures. Full article

With the intensifying global energy crisis, ensuring robust and reliable energy reserves has become crucial, and underground energy storage offers a safe, large-scale, and cost-effective solution. Among various options, salt cavern gas storage is recognized for its excellent sealing capacity and geological stability; however, many natural salt domes contain inherent fissures and interlayers (e.g., gypsum) that can jeopardize operational safety. Hence, this study aims to clarify how different fissure angles and bedding plane dip angles affect the mechanical behavior of salt–gypsum composites, providing insights for enhancing safety measures in underground gas storage facilities. Based on practical engineering demands, we employ finite element software (RFPA2.0) under a confining pressure of 25 MPa to investigate the compressive strength, fractur patterns, and acoustic emission responses of salt–gypsum composites with varying bedding plane and fissure angles. The results indicate that (1) the composite’s compressive strength gradually increases with the fissure angle, being lowest at 0° and highest at 90°; (2) as the bedding plane angle increases, the compressive strength first rises, then decreases, and finally rises again, with its minimum at 60° and maximum at 90°; and (3) when the bedding plane angle exceeds 60°, cracks preferentially develop along the bedding plane, dominating the overall fracture process. These findings provide theoretical guidance for optimizing the design and ensuring the long-term safety and stability of underground salt cavern gas storage systems. Full article

Red-bed mudstone from civil excavation is often treated as waste due to its poor water stability and tendency to disintegrate. This study proposes a sustainable approach for its utilization in controlled low-strength material (CLSM) by blending it with cement and water. Laboratory tests evaluated the fresh properties (i.e., flowability, bleeding rate, setting time, and subsidence rate) and hardened properties (i.e., compressive strength, drying shrinkage, and wet–dry durability) of the CLSM. The analysis focused on two main parameters: cement-to-soil ratio (C/S) and water-to-solid ratio (W/S). The results show that increasing W/S significantly improves flowability, while increasing C/S also contributes positively. Flowability decreased exponentially over time, with an approximately 30% loss recorded after 3 h. Bleeding and subsidence rates rose sharply with higher W/S but were only marginally affected by C/S. To meet performance requirements, W/S should be kept below 52%. In addition, the setting times remained within 24 h for all mixtures tested. Compressive strength showed a negative correlation with W/S and a positive correlation with C/S. When C/S ranged from 8% to 16% and W/S from 44% to 56%, the compressive strengths ranged from 0.3 MPa to 1.22 MPa, meeting typical backfilling needs. Drying shrinkage was correlated positively with water loss, and it decreased with greater C/S. Notably, cement’s addition significantly enhanced water stability. At a C/S of 12%, the specimens remained intact after 13 wet–dry cycles, retaining over 80% of their initial strength. Based on these findings, predictive models for strength and flowability were developed, and a mix design procedure was proposed. This resulted in two optimized proportions suitable for confined backfilling. This study provides a scientific basis for the resource-oriented reuse of red-bed mudstone in civil engineering projects. Full article

The fracturing performance of shale directly influences the effectiveness of shale gas development. To investigate the impact of bedding on the anisotropic mechanical properties and failure modes of shale under different stress paths, a shale model with randomly generated bedding planes was established using RFPA^3D. Uniaxial compression, direct tension, and triaxial compression numerical simulations were conducted. The results reveal the following key findings: (1) With an increase in the bedding angle, the uniaxial compressive strength of shale shows a U-shaped change trend, while the tensile strength gradually decreases. Under the two loading conditions, the failure mechanism of the samples is significantly different, and the influence of the bedding distribution position on the direct tensile failure mode is more significant. (2) The confining pressure reduces the brittleness and anisotropy of shale by altering the internal stress distribution and inhibiting the propagation of microcracks. When the confining pressure increases from 0 MPa to 22.5 MPa, the strength increases by about 41% when the bedding angle is 30°, while the strength of 0° bedding only increases by 29%. (3) The frictional constraint effect plays a significant role in shale strength. Frictional stresses influence the strength near the interface between the bedding and the matrix, while the regions outside this interface maintain the original stress state. In shale with inclined bedding, shear stress promotes slip along the bedding planes, which further reduces the overall strength. The research findings hold significant guiding value for optimizing fracturing designs and enhancing the efficiency of shale gas development. Full article

This study investigated the distribution and dynamics of the Turbulent Kinetic Energy (TKE) around a group of three tandem piers using a combination of numerical simulations and experimental measurements. The Volume of Fluid (VOF) method, coupled with the k-$\epsilon$ turbulence model, was implemented in ANSYS FLUENT to replicate the free-surface flow conditions. An experimental validation was conducted using Acoustic Doppler Velocimetry (ADV) to assess the model’s capability at capturing the turbulence characteristics. While the model effectively reproduced the near-bed turbulence, it consistently underestimated the TKE magnitudes across the flow domain, particularly in regions of strong vortex-induced turbulence. Discrepancies emerged in the confined regions between the piers, where the velocity profiles were overestimated at the surface and underestimated near the bed and mid-depth, impacting the TKE predictions. Despite these inconsistencies, the general pattern of the TKE distribution aligned with the experimental trends, though the absolute values remained underestimated due to the inherent limitations of the k-$\epsilon$ model. The model’s performance in less turbulent regions demonstrated improved accuracy, reinforcing its applicability for moderate turbulence simulations. To further examine the interaction between vortex structures and the TKE, velocity distributions were analyzed at three specific depths (z/h = 0.15, 0.4, and 0.62). The findings showed the critical role of vortex shedding in TKE generation and dissipation, with notable variations in the turbulence intensity influenced by structural confinement effects. This study offers a novel, high-resolution evaluation of the k-ε model’s ability to predict TKE distributions around tandem piers, using spatially detailed comparisons with the experimental data. Unlike previous studies that broadly acknowledged the model’s limitations, this work systematically identifies the specific regions, particularly vortex-dominated zones, where its predictive accuracy significantly degrades. Full article

To investigate the influence of weakly structured formations on wellbore stability in deep coal seams within the Lufeng Block, this study establishes an innovative predictive model for coal seam wellbore collapse pressure. The model integrates mechanical parameter variations along weak structural planes with the Mohr–Coulomb criterion, leveraging experimental correlations between mechanical properties and bedding angle. Key findings reveal that the coal sample demonstrates enhanced compressive strength and elastic modulus under elevated confining pressures. A distinctive asymmetric “V” pattern emerges in mechanical parameter evolution: compressive strength, elastic modulus, cohesion, and internal friction angle initially decrease before recovering with increasing bedding angle, reaching minimum values at a 60° bedding angle. Comparative analysis demonstrates that the proposed model predicts a higher collapse pressure equivalent density than conventional Mohr–Coulomb approaches, particularly when accounting for mechanical parameter alterations along weak structural planes. Field validation through coal seam data from the operational well confirms the model’s effectiveness for stability analysis in weakly structured coal formations within the Lufeng Block. These findings provide critical theoretical support for wellbore stability management in deep coal seam engineering applications. Full article

This study evaluated housing designs and bedding systems to improve air quality in swine facilities, focusing on odor and particulate matter (PM) reduction. Three experimental animal house designs (M1, M2, M3) were tested: M1 used circulating airflow with negative pressure, M2 featured a plug flow air pattern with a perforated plastic bed, and M3 employed a sawdust bedding system with recirculating ventilation. Nine fattening swine were housed in each 12 m² house over 110 days (6 May to 26 August 2018). Appropriate air samples were collected, and odorous compounds, volatile organic acids (VOA), PM, and bacterial concentrations measured. Results showed that M3 had the lowest ammonia (NH₃) levels (5.9 ± 1.5 ppm) and undetectable hydrogen sulfide (H₂S), while M1 recorded the highest NH₃ (9.1 ± 2.2 ppm). VOA concentrations were significantly lower in M3 (75 ± 1.3 ppbv) compared to M1 (884 ± 15 ppbv) and M2 (605 ± 10.3 ppbv). PM10 levels were highest in M3 (312 ± 11 μg/m³) and lowest in M1 (115 ± 3 μg/m³), and thus bacterial counts were elevated in M3 (2117 ± 411 cfu/min), whereas M1 showed the lowest bacterial count of 1029 ± 297 cfu/min. The sawdust bedding system effectively reduced odorous compounds, highlighting its potential for odor control. However, higher PM levels in M3 emphasize the need to balance environmental management with animal welfare. These findings suggest that optimizing housing designs and bedding systems can enhance air quality in swine facilities while addressing sustainability and welfare concerns. Full article

Background/Objectives: Binge Eating Disorders are severe mental and physical health conditions, closely linked to lifestyle habits. The aims are to describe the prevalence of Binge Eating Disorders and their correlation with nutritional habits and lifestyle factors within the Spanish population. Methods: A descriptive, cross-sectional design was employed. Using non-probabilistic snowball sampling, an electronic survey was released. A total of 22,181 Spanish adults were evaluated, excluding those with any pathology or limitation at the time of survey response that could potentially affect their diet, such as hospitalization or confinement. The validated Nutritional and Social Healthy Habits (NutSo-HH) scale was used to collect data on nutrition, lifestyle, health habits, and socio-demographic variables. Descriptive and inferential statistics were used. Non-parametric tests were applied due to non-normal distribution. Results: Of the 22,181 sample subject (80.8% female), a total number of 260 individuals reported Binge Eating Disorder. The prevalence of Binge Eating Disorder was higher in women than in men (239 vs. 21 respectfully; 91.9%). Individuals with Binge Eating Disorder exhibited poorer nutritional indices (p < 0.001), higher consumption of ultra-processed and fast food (p < 0.001), sugary soft drinks (p = 0.01), and worse sleep quality (p < 0.001). Although time dedicated to physical activity was not different, individuals with Binge Eating Disorder were more sedentary and had lower health status (p = 0.11 for sport practice). Behavioral regulation plays a key role in managing BED, highlighting the need for personalized intervention strategies. Conclusions: Binge Eating Disorders are associated with lifestyle and health habits and worse quality of life. These data can help design public health programs for early detection and effective treatment. Full article