Search Results (762)

A large eddy simulation (LES) model, integrated with the volume of fluid (VOF) method, was employed to investigate hydrodynamic forces and vorticity distribution around a circular cylinder in a narrow channel. The simulated surface pressure and drag coefficient closely matched the experimental results from flume testing. The ratio of cylinder diameter to channel width is defined as the blockage ratio (Br). The effects of blockage on hydrodynamic loadings and vortex structures around the cylinder were examined through a series of numerical simulations. The results reveal that blockage ratios exceeding 20% significantly alter key flow characteristics, including the upstream and circumferential pressure coefficients, drag coefficient, lateral force coefficient, and Strouhal number. Higher blockage ratios enhance near-wall vortex formation and intensify shear layers. The vertical (Ω_y), streamwise (Ω_x), and spanwise (Ω_z) vorticity components all increase with Br, leading to stronger and more spatially extensive vortex structures near the bed, particularly in the form of horizontally elongated vorticity structures. These changes have important implications for structural stability and local scour. Overall, the findings contribute to the optimization of hydraulic structure design by highlighting the effects of channel confinement on flow-induced forces. Full article

This study investigates the effects of waste for value addition in form of use of textile waste to comfortable and durable garments based on blending recycled cotton fibers extracted from spinning, weaving, and cutting waste with virgin cotton in different ratios of 70:30, 80:20, and 90:10 to produce yarns of 22/1 count, which are used to develop single jersey knitted T-Shirt, examining key properties such as mechanical and thermos-physiological properties. Grey fabric (unprocessed fabric) with a higher virgin cotton content and from spinning waste exhibited superior bursting strength, overall moisture management capacity, and thermal conductivity. In contrast, air permeability and water vapor permeability were highest in fabric made with weaving waste. After scouring and bleaching, the finished fabric (processed fabric) was compared with the grey fabrics. The results demonstrate that the finished fabric has slightly reduced bursting strength, water vapor permeability, and moisture management capacity while significantly enhancing air permeability and maintaining thermal conductivity. T-shirt properties were evaluated across various blend ratios and waste types over multiple washing cycles. Overall, the study demonstrates that recycled cotton fibers, particularly those from spinning waste, can be successfully produced into high-performance knitted t-shirts, offering a sustainable alternative to fully virgin cotton products without compromising performance significantly. Full article

Morphology is an important characteristic of the hydraulic and gravitational processes driving gully erosion. In this study, field scouring experiments were conducted on five experimental plots using terrestrial laser scanning to study gully erosion processes. The erosion and deposition on a gully slope were quantified using the M3C2 algorithm. The results show that the proportion of sediment yield of the gully slope in the whole slope–gully system ranged from 81.5% to 99.7% for different flow discharges (25, 40, 55, 70, and 85 L/min). Compared with low flow discharges (25 and 40 L/min), the gully slope presented more intense gully head retreat and higher erosion intensity under relatively high discharges (55, 70, and 85 L/min). Alcove expansion processes were characterized by horizontal and vertical cycles. Vertical dynamic changes were dominated by the co-evolution of collapses of the gully head and the deepening of the alcove. Horizontal development mainly manifested as a widening of the alcove caused by the hydraulic erosion of the gully wall. The roughness of the gully slope increased gradually with the increase in scour times and then tended towards stability. These results provide a reference for understanding the processes and mechanisms of gully erosion. Full article

Gravity erosion is one of the main physical processes of soil erosion and sediment sources in catchments, and its spatiotemporal patterns and driving mechanisms are seriously understudied, mainly due to the the great difficulties in monitoring and quantifying. This study obtained gravity erosion amounts by runoff scouring experiments on the field slope of the hilly–gully region of the Chinese Loess Plateau. The terrain point cloud before and after gravity erosion was obtained based on the TLS, SfM and the fusion of single-scan TLS and SfM, and then the gravity erosion was estimated by four terrain change detection algorithms (DoD, C2C, C2M and M3C2). Results showed that the M3C2 algorithm plus fused data had the highest quantization accuracy among all the algorithms and data sources, with a relative error of 14.71%. The fused data combined with M3C2 algorithm performed much better than other algorithms and data sources for the different gravity erosion magnitudes (mean relative error < 17.00%). The DoD algorithm plus TLS data were preferable for collapse areas, while the M3C2 algorithm plus TLS was suitable for the alcove area. This study provides a useful reference for the monitor and quantitative research of gravity erosion in complex topographic areas. Full article

The 1980 eruption of Mount St. Helens (WA, USA) presented a unique opportunity to observe primary succession in a post-eruption landscape previously dominated by conifer forests. The eruption scoured soil and biological communities adjacent to the mountain, and species of conifers have generally been slow to colonize the nutrient-poor substrate surrounding the volcano. Further, different species of conifer establish and grow at different rates. The recent advancement of conifers in the post-eruption landscape has highlighted a research gap related to conifer growth patterns. We measured the height, age, and incremental growth of 472 trees representing three common conifers, Pseudotsuga menziesii, Abies procera, and Pinus contorta, on debris avalanche (80 sites) and pyroclastic flow (82 sites) disturbance zones of the 1980 eruption. We paired annual incremental growth with recent climate data. We found that height, age, and growth rates differ among species and sites. All species had higher growth rates on the debris avalanche deposit compared to the pyroclastic flow due to either climate or substrate. Climate influences were mixed, where one species increased growth with temperature, another declined, and another was unrelated. Nevertheless, more than 40 years after the eruption, we find rapid height growth in species with implications for future forests. Full article

This article documents the widespread absence of sessile species in bedrock intertidal habitats at the head of the St. Lawrence Estuary, a large macrotidal estuary located in eastern Canada. Extensive observations revealed that no seaweeds or sessile invertebrates occurred anywhere (including cracks and crevices) on substrate areas that become exposed to the air during low tides. Only one sessile species, a green filamentous alga, was found submerged in tidepools. The lack of truly marine sessile species is likely explained by the very low water salinity of this coast, while the absence of sessile freshwater species on intertidal substrates outside of tidepools likely responds to a combination of oligohaline conditions during high tides and daily exposures to the air during low tides, which freshwater species are typically not adapted to. Influences of winter ice scour and coastal suspended sediments are likely secondary. Experimental research could unravel the interactive effects of these abiotic stressors. Overall, this “intertidal desert” could be a useful model system to further explore the boundaries of life on our planet. Full article

Time domain reflectometry (TDR) has been validated for monitoring water level evolution and riverbed scouring in the laboratory. Previous studies have also validated the feasibility of field-based single hydrological parameter monitoring using TDR. However, the current research focuses on developing separated TDR sensing systems, and integrated measurements of multiple hydrological parameters from a single reflected waveform have not been reported. This study presents an improved helical probe sensor specifically designed for implementation in geologically hard soils, together with an improved data interpreting methodology to simultaneously determine water surface level, bed elevation, and suspended sediment concentration from a single reflection signal. Experimental comparisons were conducted in the laboratory to evaluate the measuring performance between the traditional dual-needle probe and the novel spiral probe under the same scouring conditions. The experiments confirmed the reliability and superior performance of spiral probe in accurately capturing multiple hydrological parameters. The measurement errors for the spiral probe across multiple hydrological parameters were all within ±10%, and the accuracy further improved with increased probe embedding depth in the sand medium. Across all tested parameters, the spiral probe showed enhanced measurement precision with a particularly significant improvement in suspended sediment concentration detection. Full article

This study investigates the flow dynamics and local scour around a Reef Cube^® artificial reef deployed in Torbay, UK, using computational fluid dynamics. The flow is modelled using Reynolds-Averaged Navier–Stokes (RANS) equations with a k-ω SST turbulence model. A novel hydro-morphodynamic model employing the generalized internal boundary method in HELYX (OpenFOAM-based) is used to simulate scour development. Model performance was validated against experimental data for flow fields, bed shear stress, and local scour. Flow simulations across various scenarios demonstrated that parameters such as the orientation angle and arrangement of Reef Cubes significantly influence flow patterns, bed shear stress, and habitat suitability. The hydro-morphodynamic model was used to simulate scouring around a reef cube in the Torbay marine environment. Results indicate that typical tidal flow velocity flow in the region is barely sufficient to initiate sediment motion, whereas extreme flow events, represented by doubling the mean flow velocity, significantly accelerate scour development, producing holes up to ten times deeper. These findings underscore the importance of considering extreme flow conditions in scour analyses due to their potential impact on the stability and failure risk of AR projects. Full article

Xylanase is an essential industrial enzyme for degrading plant biomass, pulp and paper, textiles, bio-scouring, food, animal feed, biorefinery, chemicals, and pharmaceutical industries. Despite its significant industrial importance, the extensive application of xylanase is hampered by high production costs and concerns regarding the safety of xylanase-producing microorganisms. The utilisation of renewable polymers for enzyme production is becoming a cost-effective alternative. Among the prospective candidates, non-pathogenic lactic acid bacteria (LAB) are promising for safe and eco-friendly applications. Our investigation revealed that Pediococcus pentosaceus G4, isolated from plant sources, is a notable producer of extracellular xylanase. Improving the production of extracellular xylanase is crucial for viable industrial applications. Therefore, the current study investigated the impact of various medium components and optimised the selected medium composition for extracellular xylanase production of P. pentosaceus G4 using Plackett–Burman Design (PBD) and Central Composite Design (CCD) statistical approaches. According to BPD analysis, 8 out of the 19 investigated factors (glucose, almond shell, peanut shell, walnut shell, malt extract, xylan, urea, and magnesium sulphate) demonstrated significant positive effects on extracellular xylanase production of P. pentosaceus G4. Among them, glucose, almond shells, peanut shells, urea, and magnesium sulphate were identified as the main medium components that significantly (p < 0.05) influenced the production of extracellular xylanase of P. pentosaceus G4. The optimal concentrations of glucose, almond shells, peanut shells, urea, and magnesium sulphate, as determined via CCD, were 26.87 g/L, 16 g/L, 30 g/L, 2.85 g/L, and 0.10 g/L, respectively. The optimised concentrations resulted in extracellular xylanase activity of 2.765 U/mg, which was similar to the predicted extracellular xylanase activity of 2.737 U/mg. The CCD-optimised medium yielded a 3.13-fold enhancement in specific extracellular xylanase activity and a 7.99-fold decrease in production costs compared to the commercial de Man, Rogosa and Sharpe medium, implying that the CCD-optimised medium is a cost-effective medium for extracellular xylanase production of P. pentosaceus G4. Moreover, this study demonstrated a positive correlation between extracellular xylanase production, growth, lactic acid production and the amount of sugar utilised, implying the multifaceted interactions of the physiological variables affecting extracellular xylanase production in P. pentosaceus G4. In conclusion, statistical methods are effective in rapidly assessing and optimising the medium composition to enhance extracellular xylanase production of P. pentosaceus G4. Furthermore, the findings of this study highlighted the potential of using LAB as a cost-effective producer of extracellular xylanase enzymes using optimised renewable polymers, offering insights into the future use of LAB in producing hemicellulolytic enzymes. Full article

Fluidized solidified soil (FSS) has emerged as a promising material for marine pile scour remediation, yet its limited construction window and vulnerability to hydraulic erosion before sufficient curing constrain its broader application. This study systematically evaluates FSS formulations based on dredged sediment, cement partially replaced by silica fume (i.e., 0%, 4%, 8%, and 12%), and quicklime activation under three water–solid ratios (WSR, i.e., 0.525, 0.55, and 0.575). Experimental assessments included flowability tests, unconfined compressive strength, direct shear tests, and microstructural analysis via XRD and SEM. The results indicate that SF substitution significantly mitigates flowability loss during the 90–120 min interval, thereby extending the operational period. Moreover, the greatest enhancement in mechanical performance was achieved at an 8% SF replacement: at WSR = 0.55, the 3-day UCS increased by 22.78%, while the 7-day cohesion and internal friction angle rose by 13.97% and 2.59%, respectively. Microscopic analyses also confirmed that SF’s pozzolanic reaction generated additional C-S-H gel. However, the SF substitution exhibits a pronounced threshold effect, with levels above 8% introducing unreacted particles that disrupt the cementitious network. These results underscore the critical balance between flowability and early-age strength for stable marine pile scour repair, with WSR = 0.525 and 8% SF substitution identified as the optimal mix. Full article

Underwater jet scouring is an efficient, flexible underwater dredging technique, yet its complex physical mechanisms and dynamic evolution hinder dredging effectiveness evaluation. Existing studies mostly use empirical formulas and neglect the sediment properties’ influence on scour holes. This study integrates numerical simulation, theoretical derivation, and sediment characteristics to develop a universal model for efficiently predicting underwater jet scour hole morphology, overcoming existing models’ limitations of over-simplifying complex physics and insufficient experimental data alignment. Using CFD–DEM coupling to simulate scouring, it correlates key physical parameters (average/maximum shear rate, average/maximum shear velocity) with jet characteristics (nozzle diameter, velocity, distance) via theoretical derivation and simplifications, validated using multi-condition simulation data. Comparative analysis shows maximum relative errors of 13% for depth and 7% for width, confirming the engineering applicability in scour hole prediction. Full article

Asphalt pavement cracking represents a prevalent form of deterioration that significantly compromises road performance and safety under the combined effects of environmental factors and traffic loading. Crack sealing has emerged as a widely adopted and cost-effective preventive maintenance strategy that restores the pavement’s structural integrity and extends service life. This paper presents a systematic review of the development of crack sealing technology, conducts a comparative analysis of conventional sealing materials (including emulsified asphalt, hot-applied asphalt, polymer-modified asphalt, and rubber-modified asphalt), and examines the existing performance evaluation methodologies. Critical failure mechanisms are thoroughly investigated, including interfacial bond failure resulting from construction defects, material aging and degradation, hydrodynamic scouring effects, and thermal cycling impacts. Additionally, this review examines advanced sensing methodologies for detecting premature sealant failure, encompassing both non-destructive testing techniques and active sensing technologies utilizing intelligent crack sealing materials with embedded monitoring capabilities. Based on current research gaps, this paper identifies future research directions to guide the development of intelligent and sustainable asphalt pavement crack repair technologies. The proposed research framework provides valuable insights for researchers and practitioners seeking to improve the long-term effectiveness of pavement maintenance strategies. Full article

This study investigates the dynamic response mechanisms of discharge capacity in the Han River Estuary to hydrological process changes at the Yangtze–Han River confluence. By constructing a one-dimensional hydrodynamic model for the 265 km Xinglong–Hankou reach, we quantitatively decouple the synergistic effects of riverbed scouring (mean annual incision rate: 0.12 m) and Three Gorges Dam (TGD) operation through four orthogonal scenarios. Key findings reveal: (1) Riverbed incision dominates discharge variation (annual mean contribution >84%), enhancing flood conveyance efficiency with a peak flow increase of 21.3 m³/s during July–September; (2) TGD regulation exhibits spatiotemporal intermittency, contributing 25–36% during impoundment periods (September–October) by reducing Yangtze backwater effects; (3) Nonlinear interactions between drivers reconfigure flow paths—antagonism occurs at low confluence ratios (R < 0.15, e.g., Cd increases to 45 under TGD but decreases to 8 under incision), while synergy at high ratios (R > 0.25) reduces Hanchuan Station flow by 13.84 m³/s; (4) The 180–265 km confluence-proximal zone is identified as a sensitive area, where coupled drivers amplify water surface gradients to −1.41 × 10⁻³ m/km (2.3× upstream) and velocity increments to 0.0027 m/s. The proposed “Natural/Anthropogenic Dual-Stressor Framework” elucidates estuary discharge mechanisms under intensive human interference, providing critical insights for flood control and trans-basin water resource management in tide-free estuaries globally. Full article

The overtopping-induced lateral erosion breaching of tailings dams represents a critical disaster mechanism threatening structural safety, particularly in reinforced fine-grained tailings dams where erosion behaviors demonstrate pronounced water–soil coupling characteristics and material anisotropy. Through physical model tests and numerical simulations, this study systematically investigates lateral erosion failure patterns of reinforced fine-grained tailings under overtopping flow conditions. Utilizing a self-developed hydraulic initiation test apparatus, with aperture sizes of reinforced geogrids (2–3 mm) and flow rates (4–16 cm/s) as key control variables, the research elucidates the interaction mechanisms of “hydraulic scouring-particle migration-geogrid anti-sliding” during lateral erosion processes. The study revealed that compared to unreinforced specimens, reinforced specimens with varying aperture sizes (2–3 mm) demonstrated systematic reductions in final lateral erosion depths across flow rates (4–16 cm/s): 3.3–5.8 mm (15.6−27.4% reduction), 3.1–7.2 mm (12.8–29.6% reduction), 2.3–11 mm (6.9–32.8% reduction), and 2.5–11.4 mm (6.2–28.2% reduction). Smaller-aperture geogrids (2 mm × 2 mm) significantly enhanced anti-erosion performance through superior particle migration inhibition. Concurrently, a pronounced positive correlation between flow rate and lateral erosion depth was confirmed, where increased flow rates weakened particle erosion resistance and exacerbated lateral erosion severity. The numerical simulation results are in basic agreement with the lateral erosion failure process observed in model tests, revealing the dynamic process of lateral erosion in the overtopping breach of a reinforced tailings dam. These findings provide critical theoretical foundations for optimizing reinforced tailings dam design, construction quality control, and operational maintenance, while offering substantial engineering applications for advancing green mine construction. Full article

Among the scour protection measures for pile foundations, the use of solidified mud has demonstrated effective protection against scour. However, research on the mechanical integrity of this protective measure is relatively scarce. Therefore, a series of experiments were performed on cement-solidified soil and Enzyme-Induced Carbonate Precipitation (ECIP) solidified soil to analyze fluidity, disintegration, and unconfined compressive strength, along with an analysis of influencing parameters. Test results show the following: for cement-solidified soil, fluidity decreases with higher cement content, while its disintegration rate decreases with more cement and its unconfined compressive strength increases with a longer curing time and higher cement content. For ECIP-solidified soil, fluidity decreases with higher soy powder concentration but increases with higher binder solution concentration. ECIP’s initial disintegration rate increases with binder concentration, but after 7 days curing, its disintegration rate decreases with both higher binder concentration and higher soy powder concentration. ECIP’s strength increases with higher soy powder concentration. Crucially, both types of solidified soil exhibit decreased unconfined compressive strength with higher initial water content. The research results can provide a reference for the construction of solidified soil in the field of scour protection. Full article