Search Results (187)

Conventional early-warning methods for geohazards along railways rely largely on single observations, empirical criteria or static analysis, and struggle to meet the demands of corridor-scale screening and dynamic tracking. To address this gap, a railway-oriented Perception–Assimilation–Decision (PAD) closed-loop early-warning framework is proposed. The evolutionary patterns of typical geohazards along railways, including landslides, rockfalls, debris flows and settlement, are reviewed together with the application scope and limitations of multi-source monitoring techniques. Additionally, differentiated assimilation strategies are clarified, with continuous deformation and hydro-mechanical state updating for plastic failure and damage-sensitive evidence and critical-state identification for brittle failure. On this basis, a mechanism–data dual-driven assimilation paradigm and a two-scale PAD organisation, comprising corridor-scale spatial screening and site-scale state updating, are introduced. Recent applications show that data assimilation has shifted from correcting a single monitoring variable toward the dynamic coupling of multi-source observations with physical models. By establishing the logical chain from multi-source perception to state updating and finally to railway engineering response, the PAD framework transforms the traditional anomaly-identification-based warning mode into closed-loop risk management. The results provide a reference for building geohazard early-warning systems and engineering-oriented response along railways. Full article

Floating offshore wind turbines (FOWTs) experience coupled aero–hydro–servo-elastic excitations that produce structurally distinct kinematic responses at different measurement heights. While field monitoring campaigns increasingly deploy multi-level inertial sensors, the quantitative spectral partitioning of response energy across measurement levels and its relationship to operational and environmental conditions remain poorly characterised for operational FOWTs. This study presents a systematic multi-level spectral decomposition of operational FOWT structural response using synchronised tower-base and nacelle strapdown inertial measurements acquired at 8 Hz over a six-day campaign (18–23 April 2023) at a semi-submersible FOWT in Chinese coastal waters. Six kinematic channels—three translational acceleration components and three translational velocity components—from each sensor are decomposed into four physically defined frequency bands: drift (0.005–0.05 Hz), wave (0.05–0.30 Hz), structural (0.30–0.50 Hz), and rotor (0.50–0.80 Hz). Three derived scalar metrics—band energy ratio (BER), Wave-to-Structural Dominance Ratio (WSDR), and Structural Amplification Factor (SAF)—are defined, with their complete computation specifications and parameter sensitivity analysis provided to ensure reproducibility. Across 36 ten-minute windows spanning diverse conditions (mean wind 4.2–12.1 m/s, $H_s$ 0.8–3.1 m), results reveal a pronounced and consistent spectral separation: the tower base is strongly wave-dominated (${\mathrm{BER}}_{\mathrm{wave}}$ = 75.9%, coefficient of variation CV = 15.0% across days), whereas the nacelle exhibits substantially elevated structural-band energy (${\mathrm{BER}}_{\mathrm{struct}}$ = 10.3%, 4.72-fold amplification relative to tower base, 95% CI [3.63, 5.81]) and rotor-band energy (11.8%, 3.77-fold amplification). The WSDR at the tower base (mean 200.9, 95% CI [101.4, 300.4]) exceeds that at the nacelle (mean 48.4, 95% CI [13.1, 83.7]) by a factor of 4.1×. One-way analysis of variance (ANOVA) reveals that nacelle structural-band BER is significantly modulated by SCADA operational regime ($F=5.20$, $p=0.024$, ${\eta }^2=0.16$) and by significant wave height ($p=0.031$), while tower-base wave-band BER is primarily driven by $H_s$ ($p=0.018$). Comparison with baseline features—root-mean-square acceleration, spectral peak frequency, and traditional broad-band energy ratio—demonstrates that the band-resolved BER provides finer discrimination between excitation mechanisms than aggregate metrics. Importantly, no structural damage events occurred during the monitoring period; therefore, the reported stability of these features is interpreted as a baseline characterisation under normal operational conditions, which could support future anomaly detection efforts but does not constitute validation of damage detection capability. A comprehensive limitations assessment is provided, covering single-turbine validation, frequency-band sensitivity, regime sample imbalance, and generalisability constraints. Full article

Hydraulic fracturing in low-permeability porous rocks involves strong interactions between rock deformation, pore fluid transport, and progressive fracture damage. In this study, a hydro-mechanical phase-field model was developed to investigate hydraulic fracture evolution in saturated porous media. Biot poroelasticity, tensile–compressive strain energy decomposition, irreversible phase-field fracture evolution, and damage-dependent permeability were incorporated within a common finite element framework. The model was implemented in COMSOL Multiphysics 6.4 and used to examine the effects of the horizontal principal stress difference, injection rate, and fracturing fluid viscosity on the fracture morphology and pressure response. Within the investigated parameter ranges, increasing the horizontal principal stress difference from 2 to 14 MPa reduced the stimulated fracture area from 42,640 to 21,300 m² (50.0%) and the number of secondary branches from 12 to 5. Increasing the injection rate from 3 to 6 m³/min increased the stimulated fracture area from 35,771 to 44,138 m² (23.4%), the branch count from 6 to 11, and the breakdown pressure from 135.19 to 162.11 MPa (19.9%). Increasing the fluid viscosity from 1 to 100 mPa·s increased the stimulated fracture area from 35,771 to 48,722 m² (36.2%) and the breakdown pressure from 135.19 to 183.21 MPa (35.5%). The injection rate sensitivity was also compared with published granite hydraulic fracturing experiments, which demonstrated a positive increase in breakdown pressure with injection rate. This comparison was interpreted as trend-level physical consistency rather than direct material-specific validation because the experimental and numerical systems differed in their rock type, scale, stress state, temperature, and injection rate range. The results demonstrated systematic sensitivities of the hydraulic fracture geometry and pressure response within the investigated two-dimensional model configuration. Full article

Flash floods are among the most damaging hydrometeorological hazards in the Western Balkans (WB), yet regionally consistent, cross-border susceptibility assessments remain scarce because of fragmented national datasets and differing methodological standards. This study develops a harmonized, cloud-based flash-flood susceptibility framework for the WB (208,052 km²) by implementing a physiography-based modified Flash-Flood Potential Index (FFPI) in Google Earth Engine (GEE) at 30 m resolution. The modified FFPI integrates slope, land cover, soil texture, vegetation exposure (Bare-Soil Index), and soil erodibility, and is aggregated across 9524 EU-Hydro sub-basins to produce an operational catchment-level ranking. Additionally, CHIRPS-derived maximum daily precipitation is used to derive a rainfall-triggered hotspot layer that highlights sub-basins where terrain-controlled susceptibility coincides with strong observed rainfall extremes over the 2001–2025 period. Enhanced susceptibility is concentrated in Adriatic and Aegean-facing mountain basins of Albania, Montenegro, and North Macedonia, with 44.2% of sub-basins classified as high or very-high susceptibility. Multi-source validation against inventoried torrential catchments, published GIS-based susceptibility maps, and flood records yielded moderate to very strong agreement (68.6–92.0%), together with an AUC-ROC of 0.79 and F1-score of 0.77 for the pooled orthophoto-based validation dataset (n = 336 sub-basins). The framework provides a reproducible transboundary tool for regional flood-risk screening and demonstrates the potential of cloud-based geospatial platforms to overcome cross-border data fragmentation in hazard assessment. Its main limitations are the static physiographic nature of the FFPI, the coarser resolution of CHIRPS and SoilGrids relative to small sub-basins, and possible overestimation in karst terrains where subsurface drainage reduces surface runoff. Full article

To investigate the mechanical response and energy-damage evolution of argillaceous sandstone under coupled hydro-softening and confining pressure effects, triaxial compression tests were conducted under different water contents (0%, 3.1%, 6.2%, and 9.3%) and confining pressures (0, 3, 6, 10, and 15 MPa). The stress–strain characteristics, failure modes, strength criteria, and energy evolution laws were systematically analyzed. The results show that argillaceous sandstone exhibits a pronounced hydro-softening effect. When the water content increased from 0% to 9.3%, the peak strength decreased by 28.5–50.3% under different confining pressures, with more significant deterioration at the low-water-content stage. Increasing the confining pressure from 0 to 15 MPa increased the peak strength by 180–240% and enhanced the plastic deformation capacity, partly offsetting the weakening induced by hydro-softening. Regression analyses indicate that the exponential strength criterion provides the best applicability for the triaxial strength of argillaceous sandstone. The proposed water-content-modified exponential strength criterion can characterize both hydro-softening and confining pressure effects, with an average relative error of 2.11% and a maximum relative error of 4.70%. Energy analysis shows that increasing water content reduced the elastic energy storage capacity; under uniaxial compression, the peak elastic strain energy at 9.3% water content was 64.4% lower than that in the dry state. The energy-based damage model can describe the pre-peak damage evolution and stress response of argillaceous sandstone. The results can provide a theoretical basis for the stability evaluation of surrounding rock in water-rich soft rock underground engineering. Full article

To overcome the limitations of conventional homogeneous materials in floating photovoltaic (FPV) systems, this review critically examines advanced material-s design strategies and fabrication approaches that enable enhanced durability, reliability, and performance under coupled hydro-mechanical and environmental loading conditions. Although FPV systems provide a scalable solution to land scarcity, their long-term operation is challenged by wind–wave interactions, persistent moisture exposure, thermal cycling, and corrosion-induced degradation, and biofouling, requiring materials capable of accommodating spatially varying and interacting stressors. Functionally graded materials (FGMs) are explored as a promising solution, enabling continuous variation in the composition and microstructure to tailor local mechanical, thermal, and chemical properties within a single structure. Recent research highlights growing interest in additive manufacturing and gradient design, but limited focus on FPV and marine applications. Emphasis is placed on additive manufacturing as a key fabrication route for realizing complex gradient architectures with high precision and design flexibility. Recent advances demonstrate notable improvements in corrosion resistance, fatigue performance, and stress distribution, leading to the enhanced structural integrity and service life of FPV systems. The review further organizes FGM concepts within a design–process–property–performance framework and discusses their application in key FPV subsystems. This review further evaluates the role of multi-physics modelling and digital twin frameworks in linking processing conditions with in-service performance under realistic operating environments. The potential of computational intelligence approaches for predicting thermo-mechanical response, damage evolution, and reliability of graded structures is also discussed. Additionally, emerging challenges related to gradient characterization, standardization, technology qualification and scalability, and large-scale deployment are critically discussed, highlighting key directions for future research and technological development. Overall, FGMs and advanced manufacturing show strong potential to improve FPV durability, fatigue resistance, and corrosion performance. Full article

Subsea tunnels constructed by the drill-and-blast method are increasingly required in modern infrastructure and are often exposed to high groundwater pressure and fractured rock conditions. In such environments, external water pressure acting on initial support strongly affects tunnel stability, durability, and construction safety. Because the initial support is temporary, discontinuous, and prone to cracking, evaluation of its water pressure response remains challenging. Current design practice relies on simplified assumptions and empirical approaches, inadequate for fractured rock masses under high water pressure. This review synthesizes research on external water pressure in tunnels, with emphasis on drill-and-blast subsea tunnels. Empirical reduction coefficient methods, theoretical analytical solutions, numerical techniques, and physical model testing are critically examined in terms of their theoretical basis, applicability, and limitations. Special attention is given to seepage behavior in fractured rock masses, including single-fracture seepage laws, equivalent continuum models, and discrete fracture network approaches, and their ability to represent fracture-controlled flow and water pressure redistribution. The review shows that conventional seepage or seepage–stress coupled methods are insufficient to capture stress redistribution, fracture evolution, and damage-induced permeability changes governing water pressure behavior. By contrast, advanced coupled stress–seepage–damage and stress–seepage–fracturing models provide more physically consistent frameworks for analyzing external water pressure acting on initial support. In addition, hydro-mechanical discrete lattice models are reviewed as a promising meso-scale framework for capturing crack initiation, crack coalescence, and crack-controlled seepage paths that may govern localized external water pressure redistribution behind initial support. However, their application to subsea tunnels remains limited, and current design codes still lack unified calculation methods. Major challenges remain, including the lack of consistent definitions of external water pressure, inadequate consideration of the interaction between tunnel support and surrounding rock, and insufficient validation through laboratory experiments and field observations. Future research should develop mechanism-based methods supported by monitoring and validation to improve subsea tunnel safety. Full article

The fractal characteristics of coal pore–fracture networks and their evolution under compression are essential for predicting rock mass failure and fluid transport. This study combines micro-CT scanning with fractal theory and seepage mechanics to investigate the structural evolution of coal under uniaxial compression and its impact on fluid transport. CT scans were performed at four characteristic stages (initial, elastic, plastic, and failure) to reconstruct three-dimensional fracture networks. Quantitative analysis reveals that fracture porosity increases sequentially from 0.44% to 5.01%, with the failure stage reaching 11.4 times the initial value. Fracture length and aperture distributions follow power-law scaling, and their fractal dimensions exhibit distinct evolution patterns: length dimension increases from 2.43 to a peak of 2.56 in the plastic stage and then drops to 2.47 at failure, while aperture dimension decreases from 2.29 to a trough of 2.12 before rebounding to 2.26. These patterns reflect a dynamic adjustment of network complexity, transitioning from primary fractures to micro-fracture dominance and finally to main fracture coalescence. Based on the Knudsen number, three diffusion regimes of Fick, transition and Knudsen are identified. A fractal permeability model is developed by idealizing the pore space as tortuous capillaries, showing that permeability scales with the fourth power of the maximum pore diameter and is positively influenced by the fractal dimension and the number of large pores. Furthermore, a coupled seepage–stress model is derived, incorporating pressure transmission, shear transmission, and crack opening coefficients. The damage variable is expressed as a function of stress level and fractal dimension. These findings provide theoretical support for predicting gas transport and failure behavior in coal under coupled hydro-mechanical conditions. Full article

To clarify how injection-induced cooling and reservoir properties jointly control rock damage during hydraulic fracturing of deep shale reservoirs, this study develops a coupled thermo–hydro–mechanical phase-field model incorporating fracture pressurization, matrix seepage, heat transfer, thermoelastic stress redistribution, and tensile damage evolution. The hydraulic fracture component is verified against the classical KGD analytical benchmark, and the thermal damage component is benchmarked against a ceramic quenching experiment. The phase-field formulation is constructed using tensile-compressive strain-energy decomposition so that only the tensile part of the elastic energy contributes to damage evolution, while the compressive stiffness is retained. The results show that low-temperature fluid injections produce a steep but spatially limited cooling zone near the fracture wall. The constrained contraction of the cooled rock generates additional thermoelastic tensile stress, strengthens fracture-tip stress localization, and accelerates phase-field damage accumulation. In the baseline case, thermal cooling increases the peak tensile stress near the fracture tip along profile c from 10.2 MPa in the hydraulic-only case to 22.5 MPa at t = 2 h, while the phase-field damage value increases from 0.03 to 0.77. Five-case sensitivity analyses show that, as α_T increases from 0.5 × 10⁻⁵ to 1.5 × 10⁻⁵ 1/°C, the fracture-tip tensile stress at t = 2 h increases from approximately 18.6 MPa to 25.7 MPa, and the damage value increases from approximately 0.80 to 0.96. As permeability increases from 0.0001 mD to 0.01 mD, the pore pressure at 2 m from the fracture wall increases from approximately 50.4 MPa to 71.2 MPa, and the tensile stress along profile c increases from approximately 16.4 MPa to 21.8 MPa. These results demonstrate that coupled thermal and hydraulic effects govern fracture initiation, localization, and propagation tendency during thermally assisted hydraulic fracturing in deep shale reservoirs. Full article

Fractured coal in the residual-strength stage is a primary medium for gas migration and drainage in deep mining areas. To investigate the hydro–mechanical seepage response of post-peak fractured coal under constant-pressure-difference conditions, triaxial CO₂ seepage tests were conducted on coal specimens collected from the Xinyuan Coal Mine. A Weibull-based damage constitutive model was established to characterize the confining-pressure-induced hysteresis in the damage-evolution path. The flow-rate evolution and Reynolds number analysis indicated that gas flow remained within the linear Darcy regime. A controlled-variable analysis was used to examine the competing effects governing permeability evolution. Mechanical compaction induced an exponential decrease in permeability, whereas the decrease in permeability with increasing pore pressure was interpreted, within the proposed model framework, as the combined effect of possible adsorption-induced matrix swelling and weakened gas slippage. To address the limitations of conventional constant-slip-factor models, a pressure-dependent slip modulation coefficient was introduced into a composite permeability equation incorporating effective stress, adsorption-related deformation, and dynamic gas slippage. Global nonlinear fitting yielded R² = 0.97 and an RMSE of 0.1909, with the residuals generally distributed around zero, supporting the fitting reliability of the model within the investigated stress–pressure range. Response-surface analysis identified mechanical compaction as the dominant controlling mechanism, while adsorption-related deformation and gas slippage acted as secondary correction mechanisms. The proposed framework provides a quantitative basis for distinguishing the mechanical and fluid-related effects governing permeability evolution in post-peak fractured coal. Full article

In the seasonally frozen area, slopes are exposed to freeze–thaw cycles; thus, water and heat are moved, and the foundation for the transportation infrastructure in cold regions may be weakened. Based on the relatively strong water-recharge effect and considerable fluctuations in shallow soil moisture during the spring thaw along the Naba section of the G218 Highway in Xinjiang, China, a coupled hydro-thermal model for frozen soil that considers snowmelt infiltration and rainfall recharge was developed, and it was numerically implemented in COMSOL. A one-dimensional unidirectional freezing test of a soil column was used to validate the model, and the relative errors of the simulated temperature and moisture fields were 3.8% and 4.3%, respectively; both are within the accuracy requirements for engineering-scale analysis. Then, a model was used to determine how the temperature, volumetric ice content and volumetric water content of a representative slope in the Naba section changed during a freeze–thaw cycle. Based on the above results, the annual temperature range at the surface of the topsoil on the slope is 37.61 °C, and this thermal effect extends to a depth of 0–3 m. In the spring thaw, the volumetric water content of the surface layer increased from 8.45% in February to 19.34% in May, and further to 20.65% in July; therefore, it can be inferred that the shallow soil is still being replenished by snowmelt and rain. Freezing-thaw phase change, freezing-front migration and external water infiltration work together to control hydro-thermal transport in the slope; thus, a redistribution and local accumulation of liquid water occur below the residual frozen layer and under the shallow surface. The above results can serve as a reference for drainage design and as a means to prevent or control freeze–thaw damage to the slope of a highway in Xinjiang’s seasonally frozen area during the spring thaw. Full article

Amid the global transition to low-carbon energy systems, unconventional oil and gas resources play a key role in ensuring energy security. Hydraulic fracturing is a central technology for unconventional resource development, but it may also induce seismicity. This study investigates energy release and induced seismicity during hydraulic fracturing in naturally fractured media. A fully coupled hydro-mechanical-damage (HMD) model combined with a discrete fracture network (DFN) is developed to represent natural fractures in shale reservoirs. By incorporating frictional contact and shear slip, the model simulates tensile propagation of hydraulic fractures and shear slip of natural fractures. Parameter sensitivity analyses are conducted for natural fracture characteristics, differential stress, elastic modulus, and injection rate. The energy release of shear slip and tensile propagation is compared based on total seismic moment. Results show that the seismic moment generated by natural fracture shear slip is several orders of magnitude higher than that from tensile propagation, indicating that shear slip is the dominant energy release mechanism. Increasing the number and length of natural fractures enhances fracture-network connectivity and pressure diffusion, making natural fractures more prone to shear instability. Higher differential stress, elastic modulus, and injection rate may further promote slip-induced energy release and elevate induced seismic risk. These findings provide a theoretical basis for seismic risk assessment and parameter optimization in hydraulic fracturing. Full article

Cannabis sativa L. is a medicinal plant cultivated globally due to its remarkable historical and scientific relevance. Through the consumption of its flowers, also referred to as inflorescences, which contain a high content of cannabinoids, terpenes and polyphenols, the therapeutic properties of C. sativa can be harnessed. This study therefore aimed to determine the chemical profile, antioxidant and anti-inflammatory activities of the essential oils (EOs) obtained from the fresh and dried flowers of two C. sativa cultivars, Lifter and Cherrywine, grown in Komga, South Africa, to assess which cultivar has greater biological potential. The chemical profiles of the hydro-distilled EOs were analyzed by gas chromatography–mass spectrometry (GC-MS), while the in vitro antioxidant and anti-inflammatory activity of the EOs was analyzed using the DPPH and EAD methods, respectively. The identified constituents from the EOs were molecularly docked against NOX2 and NIK (NF-κB-inducing kinase) protein, which are implicated in oxidative stress. The afforded EOs were yellow (pale and bright yellow) in color with a sweet to mildly sweet aroma description. A total of 51 constituents were identified in both fresh and dry oils from the Lifter cultivar, while the Cherrywine cultivar contained a total of 44 constituents. Eighteen compounds, were found to be the main chemical constituents consistent in the flower EOs of both cultivars, notably, caryophyllene (10.71–19.96%), levo-β-pinene (1.37–13.21%), humulene (5.88–9.77%), caryophyllene oxide (4.32–7.49%), D-limonene (1.40–5.48%), α-pinene (2.22–5.22%), nerolidol (0.63–4.97%), cis-β-ocimene (0.22–4.37%), linalool (1.12–4.28%), selina-3,7(11)-diene (0.15–4.23%), humulene-1,2-epoxide (1.23–3.32%), guaiol (0.17–2.60%), (+)-β-selinene (1.20–2.51%), trans-α-bergamotene (0.68–2.37%), β-ocimene (0.90–2.27%), fenchol exo- (0.15–1.27), terpineol (0.14–1.38%) and α-terpineol (0.19–0.75%). The fresh Lifter flower oil (LFO) showed 50% inhibition at 100 μg/mL, with an IC₅₀ of 69.50 ± 4.05 µg/mL against DPPH, suggesting moderate to low radical scavenging activity. The maximum percentage inhibition response of DLFO, CFO and DCFO remained below 50% at all concentrations. The antioxidant activity of fresh LFO may be attributed to its overall chemical composition. The flower oils showed in vitro inhibition of protein denaturation; however, the high standard deviation relative to the mean IC₅₀ values limited the ability to rank the samples’ potencies. Further in silico studies on the putative constituents in the Lifter and Cherrywine cultivars revealed β-bisabolene and α-curcumene as potential molecular targets, with binding energy scores of −7.7 and −7.9 kcal/mol, respectively. Thus, the study findings highlight the promising biological importance of C. sativa inflorescences in the management of oxidative stress-related conditions. Further studies may investigate the influence of environmental growing conditions on their chemical composition, total ROS analysis, pharmacokinetic properties, and in vivo efficacy against oxidative damage to DNA, proteins and lipids. Evaluating the toxicity of the flower EOs is also recommended. Full article

The model is based on the periodic translational symmetry of regular saw-toothed joint surfaces and reveals the time-dependent breaking of this symmetry under hydro-mechanical coupling through the introduction of damage evolution. Traditional creep models typically rely on static constants, which fail to capture the nonlinear, time-dependent degradation of rock under complex conditions. To address this, this paper proposes a novel nonlinear shear creep model for regular saw-toothed joint surfaces under hydro-mechanical coupling. First, a calculation method for effective shear stress is established, accounting for normal stress, asperity height, and water pressure. Next, traditional static parameters are transformed into dynamic variables to accurately model the primary and steady-state creep stages. Finally, a plastic damage element is introduced to simulate the accelerated creep stage, revealing that damage accumulates with time and is exacerbated by higher seepage pressure. By integrating early-stage viscoelastic and late-stage viscoplastic characteristics, this model captures the complete nonlinear shear creep process, providing a robust theoretical basis for long-term stability evaluations. Full article

Climate-driven intensification of pluvial and fluvial flooding increasingly challenges lowland cities in Central Europe, while conventional protection and land-use controls offer limited flexibility under growing hydrological variability. A planning-oriented framework is developed and tested to integrate hydro-adaptive housing into climate-resilient urban development using three typologies: elevated foundations, amphibious dwellings and modular floating platforms. The framework links hazard profiles and site-enabling conditions to typology selection and considers supporting blue–green measures within the broader adaptation context. It is applied to three flood-prone settings in northern Poland representing a coastal delta, a river confluence and a lower-river terrace. The methodology combines GIS-based hazard mapping; one-dimensional unsteady-flow HEC-RAS simulations for 50-, 100- and 500-year design events; and parametric structural modelling in Rhino–Grasshopper. Performance is assessed using maximum inundation depth, surface-water retention time, and a probabilistic building damage index. Amphibious dwellings reduce modelled 100-year flood damage by 62% relative to slab-on-grade construction, while modular floating platforms maintain habitability under water-level rises exceeding 5.0 m. In addition, bioretention and blue–green corridors reduce retention time by 18–31%. The results provide a planning-oriented decision logic for expanding adaptive housing options in flood-prone lowland settings under increasing hydrological variability. Full article