Search Results (3,209)

Expansive soil slopes are highly susceptible to rainfall-induced shallow failures due to cyclic swelling–shrinkage behavior governed by matric suction variation. This study proposes a composite frame–geosynthetic system (CFGS), comprising a rigid frame integrated with high-performance turf reinforcement mats (HPTRMs), for expansive soil slope protection. The performance of the CFGS was evaluated through geometrically scaled, materially representative physical model tests under repeated wetting–drying cycles and further examined using coupled hydro-mechanical numerical simulations in COMSOL Multiphysics. A bare slope and an HPTRM-protected slope were used for comparison. Under identical laboratory conditions, CFGS reduced cumulative erosion to approximately 13% of that of the bare slope. It also moderated the internal hydraulic response, reducing pore-water pressure fluctuation by approximately 26%, and restrained swelling–shrinkage deformation, with an average deformation attenuation of up to 61%. The numerical simulations showed consistent response trends with the physical model tests, supporting the proposed mechanism of hydraulic regulation, deformation restraint, and stress redistribution. Overall, the results demonstrate the comparative effectiveness of CFGS in mitigating wetting–drying-induced deterioration of expansive soil slopes. Full article

This study investigates the influence of inside-trapped water and remedial grouting on the vertical bearing behaviour of suction bucket foundations in sand through 1 g laboratory model tests. The tests were designed to compare the relative responses of different trapped-water and grouting conditions under the same model scale, sand preparation procedure, and loading protocol. Two target trapped-water conditions were considered: a condition without an observable continuous water layer beneath the bucket lid and a condition with an initial trapped-water thickness of approximately 2 cm. These conditions were controlled and verified before loading using the scale attached to the transparent bucket wall and the underwater camera monitoring system. The results show that inside-trapped water modifies the vertical load-transfer path between the bucket lid and the internal soil plug. When a water layer exists beneath the lid, direct lid–soil plug contact is weakened, and the foundation resistance relies more strongly on skirt-side resistance and the resistance mobilized near the bucket rim. Under cyclic vertical loading, the trapped-water case exhibited larger cumulative displacement and a lower post-cyclic bearing response than the no-trapped-water case. The secant cyclic stiffness showed a continuous increase in the no-trapped-water case, whereas a rise-then-fall trend was observed in the trapped-water case, which may be associated with cyclic densification, soil plug disturbance, changes in lid–soil plug contact, and possible local pore pressure development. Remedial grouting filled the trapped-water space beneath the bucket lid and partially restored the lid–soil plug load-transfer path. Under the present model test conditions, the post-cyclic dimensionless bearing capacity of the grouted cases increased by approximately 13–16% relative to the ungrouted trapped-water case. The grouting cases with different bentonite contents showed similar recovery trends within the limited dataset, suggesting that the improvement was mainly related to filling and sealing the trapped-water space rather than to the intrinsic strength of the grout material. Full article

Fracture–vuggy carbonate reservoirs contain discrete caves, fractures, conduits, and vugs, which makes recoverable-reserve evaluation strongly dependent on connected volume rather than on total pore volume alone. This study develops a unit-scale dynamic reserve-updating method for the S48 unit, Tahe Oilfield, by coupling a water-body-corrected material-balance equation, a heterogeneity-corrected waterflood characteristic curve, and iterative geological-model calibration. The main methodological contribution is to convert static fracture–vug architecture into dynamically constrained connected subsystems: the parameter Rwo quantifies connected/injected water volume at the fracture–vug unit scale, whereas the coefficient M corrects the apparent slope of waterflood curves for non-uniform sweep and preferential pathways. The revised workflow was calibrated against pressure, production, injection-response, and history-matched simulation data. Sensitivity analysis indicates that the estimated reserve-utilization degree increased from 48.77% +/− 4.8 percentage points during natural depletion to 74.1% +/− 6.7 percentage points after gas injection, reflecting staged reserve mobilization within the tested uncertainty range. The method is intended for field-scale reserve updating in reservoirs with sufficient pressure-production data; its transferability remains limited by static-model quality, channeling intensity, and the single-unit validation scope of this study. Full article

With the rapid development of the edible fungus industry, the environmental pressure and resource waste caused by the massive generation of fungal residue have become increasingly prominent. Meanwhile, heavy metal wastewater pollution and the growing demand for clean energy pose dual challenges to sustainable development. This study focuses on Auricularia cornea var. Li. fungal residue, exploring the establishment of a multi-level resource utilization pathway integrating “porous carbon material preparation—heavy metal adsorption—photocatalytic hydrogen evolution.” Firstly, the Auricularia cornea var. Li. residue-based porous carbon material was examined by combining hydrothermal carbonization, activation and slow pyrolysis. In optimal conditions, the porous carbon obtained yielded a surface area of 675.56 m²/g and formed a composite pore structure consisting of micropores with coexisting micropore and mesopore. Secondly, we performed batch adsorption experiments to study the effects of solution pH, adsorbent dosage and contact time and the adsorption behavior via fitting adsorbing kinetic models. Under optimal conditions, Cd(II) removal efficiency reached 92.36% and an equilibrium adsorption capacity of 92.47 mg/g. We used Cd(II) adsorbed porous carbon as a cadmium source and converted into a CdS photocatalyst using a hydrothermal sulfidation process. The CdS prepared using sodium sulfide as a sulfur source gave an average hydrogen evolution rate of 668.01 μmol·g⁻¹·h⁻¹ and showed higher photocatalytic performance for water splitting to produce hydrogen. Full article

This study was performed to elucidate the mechanism underpinning the nodal swelling induced by equinatoxin II (EqtII), a cation-selective pore-forming toxin derived from the sea anemone Actinia equina. Experiments were conducted using frog myelinated nerve fibers as a model system. Application of EqtII led to an approximately two-fold increase in the nodal volume of myelinated axons, but only when extracellular Ca²⁺ was present. Replacing extracellular Cl⁻ with isethionate had no measurable effect on this response, whereas substitution of NaCl with either sucrose or LiCl, an established Na⁺/Ca²⁺ exchanger (NCX) inhibitor, abolished the swelling. The persistence of the effect in the presence of tetrodotoxin indicates that voltage-gated Na⁺ channels are not involved in the underlying mechanism. Our data suggest that Ca²⁺ influx through EqtII-induced membrane pores raises intracellular Ca²⁺ levels, thereby stimulating the NCX in its forward-operating mode. This process promotes Ca²⁺ extrusion in exchange for Na⁺ entry. The resulting accumulation of intracellular Na⁺ increases osmotic pressure within the axon, leading to water influx and nodal swelling. Full article

Capillary imbibition is the process by which liquids are absorbed into porous materials as a result of capillary pressure differences at the pore scale. Accurate characterization of imbibition dynamics, particularly in the presence of gravitational potential, is essential for understanding fluid transport in diverse systems such as soil, fractured rocks, filtration media, and plant roots. This study presents systematic imbibition experiments using filter papers with pore sizes of 2.5 µm, 11 µm, and 20 µm, each inclined at 80° to quantify the influence of gravitational potential on imbibition behavior. For horizontally positioned samples, the imbibition front propagated radially and symmetrically, exhibiting a power law dependence on time. The measured temporal exponents ranged from 0.386 to 0.403, consistently lower than the theoretical value of 1/2 predicted by the Lucas–Washburn law. With increasing permeability, the temporal exponent approached the Washburn limit, indicating a marked dependence of imbibition dynamics on pore structure. For the inclined configuration at an 80° angle, the imbibition fronts remained nearly circular but exhibited a pronounced displacement of the front center toward gravity. This displacement increased with permeability, from approximately 0.497 cm for the 11 µm filter paper to 3545 cm for the 20 µm filter paper, highlighting the combined effects of permeability and gravitational potential on fluid movement. Furthermore, the advance of the imbibition front was significantly slower in the smallest pores (2.5 µm) compared to the larger ones. Experimental results were evaluated against a theoretical model proposed by Medina, demonstrating moderate quantitative agreement at early times, when gravitational potential effects are less significant. These findings confirm that both the temporal scaling exponent and the spatial evolution of the imbibition front are governed by the porous medium’s permeability and inclination angle, providing experimental evidence of deviations from ideal Washburn behavior in real porous systems. Full article

The effective utilization of recycled concrete powder remains a key challenge for sustainable construction. In this study, carbonated recycled concrete powder (CRCP) was applied to replace cement at levels of 4–16% in Portland cement–fly ash (OPC-FA) systems, and its effects on fresh properties, hydration behavior, shrinkage, pore structure, and mechanical performance were systematically investigated. The incorporation of CRCP reduced flowability and accelerated setting, while slightly advancing and enhancing the main hydration peak at 4–8% replacement, accompanied by higher CH at early ages and increased C–S–H formation at later stages. More significantly, the addition of CRCP substantially decreased both autogenous and drying shrinkage, achieving reductions in the ranges of 6.0–21.4% and 3.2–24.1%, respectively. This improvement is primarily attributed to the elevated internal relative humidity and the lowered capillary pressure within the system. In addition, the mechanical properties exhibited a clear optimum with the addition of 8% CRCP, where the 28 d compressive strength and flexural strengths increased by 16.3% and 4.0%, respectively. Further analysis indicates that this improvement is associated with a higher fraction of high-modulus regions and an increase in average elastic modulus from 23.89 GPa to 27.42 GPa, reflecting a denser microstructure. These results demonstrate that CRCP can effectively regulate hydration and microstructure, providing a feasible approach for improving dimensional stability and mechanical performance while enabling the value-added utilization of recycled concrete powder. Full article

Deep coalbed methane (CBM) has become an important contributor to natural gas production worldwide. Its fluid occurrence characterized by high free gas content and low water saturation suggests substantial gas-driven displacement caused by hydrocarbon generation overpressure. However, the microscopic evolution of this process and the corresponding occurrence remain poorly understood. To address these issues, we combined centrifugation experiments, nuclear magnetic resonance (NMR) monitoring, and theoretical modeling to systematically investigate pore-scale displacement dynamics and the associated fluid distribution. A dynamic evolution model for gas–water displacement in nanopores is developed by incorporating the capillary pressure and disjoining pressure, and validated against the centrifugation experimental data. At the pore scale, gas–water displacement is governed by critical displacement pressure and water film thickness. Water saturation declines sharply once the displacement pressure exceeds a critical threshold, after which it decreases slowly as the water film progressively thins. At the porous media scale, water saturation continuously decreases with increasing displacement pressure. For the high-rank coal samples in this study, the overall water saturation decreases to 49.15% as the displacement pressure increases to 10 MPa. The water film is negligible for pores larger than 20 nm, but significant for pores smaller than 20 nm. This critical pore size is not fixed, but is a dynamic threshold controlled by the disjoining pressure parameter. The occurrence of free gas in deep CBM is governed by the relative matching between hydrocarbon generation overpressure and reservoir pore structure. These findings provide a theoretical basis for resource assessment and efficient development of deep CBM. Full article

Persistent uncertainty in translating low-field nuclear magnetic resonance (NMR) T₂ relaxation spectra into geometrically meaningful pore–throat metrics has long hindered the quantitative characterization of tight reservoirs. To address this issue, this study develops an enhanced conversion framework that incorporates scale-dependent pore geometry, enabling more realistic estimation of pore–throat radius distributions. Core samples were collected from the first member of the Shanxi Formation and the eighth member of the Shihezi Formation in the Ordos Basin. A comprehensive experimental dataset was established, including porosity and permeability measurements, X-ray diffraction (XRD) mineral analysis, NMR experiments, high-pressure mercury intrusion (HPMI), and constant-rate mercury injection (CRMI). The results demonstrate that total clay content exhibits weak correlations with pore size and porosity. In contrast, the occurrence and morphology of specific clay minerals exert significant control on pore connectivity and flow behavior. In particular, fibrous illite increases pore–throat complexity, while early chlorite coatings help preserve primary intergranular pores. A single geometric model cannot fully represent the complex pore–throat system in tight sandstones. For pores, a spherical geometry is most appropriate and indeed necessary. Smaller throats connecting these pores often exhibit geometries more consistent with cylindrical shapes. Within the coarse pore size range, large pores dominate the reservoir space and generally exhibit geometries that better conform to a spherical shape. And larger pores dominate the volumetric contribution in the coarse pore-size range. These observations suggest that a scale-dependent composite model could further improve the accuracy of NMR-based pore-size estimations. Therefore, the spherical-pore model provides a physically meaningful framework for characterizing pore structures in tight reservoirs. At the same time, incorporating scale-dependent considerations offers a promising avenue for future methodological development. Full article

Deepwater shallow gas sediments and the weakly consolidated overburden are sensitive to depletion-induced effective stress redistribution. Since deepwater shallow gas has only recently begun to be treated as a commercially available natural gas resource, it lacks models to quantify the coupled flow and geomechanical behaviors in such environments. In this study, we propose a semi-analytical model for a shallow gas layer and its overburden sediments, where pore pressure evolution is described by vertical transient diffusion and the stress response is represented by an OCR-dependent (overconsolidation ratio-dependent) in situ stress field with depletion-induced effective stress increments. Pre-yield compressibility is characterized by a stress-dependent nonlinear elastic law, and post-yield deformation is approximated by a Mohr–Coulomb-based yield-controlled plastic correction for engineering purposes. The formulation is used in the base case and during a parametric sensitivity analysis. In the base case, the final settlement is 0.597 m, of which 45.3% is elastic and 54.7% is plastic. The sediments begin to yield after approximately 115 d of production, and the final yielded-thickness fraction reaches 0.268. The sensitivity analysis shows that friction angle, maximum drawdown, gas-layer thickness, and OCR magnitudes predominantly affect the final settlement and yielded-thickness response, while gas-layer permeability has an insignificant effect. Furthermore, the comparison reveals that the depletion timescale governs the stress evolution rate, while depletion pressure drawdown magnitude dictates deviatoric stress evolution and long-term settlement. Considering the engineering condition for the development of typical deepwater shallow sediments, the feasible production parameters should be in the low-to-moderate drawdown and slow depletion range. A practical operating window is approximately 3.6~4.0 MPa maximum drawdown with a depletion timescale of about 340~400 d. This study can provide quantitative insights into the potential commercial production of gas layers in deepwater shallow sediments. Full article

Membrane distillation (MD) is an attractive complementary technology to conventional desalination systems. Yet commercial uptake remains limited by membrane pore wetting, temperature polarisation, and material trade-offs. This review critically examines polymeric membranes and demonstrates that reported performance gains cannot be attributed to individual polymers or fillers alone, but rather to optimised structure–property interactions governing wetting resistance, mass transfer, and mechanical integrity. Through a comparative analysis of benchmark metrics (water flux, contact angle, and liquid entry pressure), we identify recurring failure mechanisms, including nanoparticle agglomeration, coating instability, and hydrophobicity-driven compromises in liquid entry pressure and durability. Moving beyond a descriptive summary of materials, this review introduces a predictive structure–property–performance framework that systematically links dominant operational limitations and targeted modification strategies. The analysis reveals that surface-localised, adhesion-controlled modifications outperform bulk approaches by preserving pore architecture while mitigating fouling and wetting risks. Key research priorities include validation under high-salinity conditions relevant to brine management, standardised environmental and leaching assessments of nanomaterials, scalable fabrication protocols supported by techno-economic considerations, and developments on bioinspired materials. By shifting focus from material novelty toward rational design principles, this review establishes actionable selection criteria to accelerate the translation of MD membranes from laboratory concepts to industrially viable desalination technologies. Full article

The Ili River Valley is a typical seasonally frozen region in which slope instability frequently occurs during the warm frozen-soil stage, generally at temperatures ranging from approximately −1.5 to 0 °C. In this context, changes in unfrozen water content play an important role in controlling the pore structure and mechanical behavior of warm frozen soil, yet the links among these factors remain insufficiently understood. This study investigates warm frozen soil from the Ili River Valley, with particular emphasis on the role of unfrozen water content in regulating pore-structure characteristics and mechanical response under low-temperature conditions. Low-field nuclear magnetic resonance (NMR), low-temperature triaxial shear tests, scanning electron microscopy (SEM), and quantitative image analysis were employed to examine the relationships between unfrozen water content, pore structure, and macroscopic mechanical properties under different temperatures, initial water contents, and confining pressures. The results show that unfrozen water content decreases markedly with decreasing temperature, especially within the range of −1.5 to −5 °C, and increases with increasing initial water content. These changes are accompanied by significant variations in porosity, pore abundance, and pore fractal dimension, reflecting freezing-induced reorganization of the pore system. Lower temperatures and higher initial water contents promote ice-crystal growth and the formation of larger ice-cemented aggregates, thereby modifying the pore framework. Meanwhile, peak strength and cohesion increase with decreasing temperature and increasing initial water content, whereas the internal friction angle shows a decreasing trend. In addition, porosity, pore abundance, and pore fractal dimension are closely correlated with peak strength and cohesion. The results indicate that unfrozen water content governs the freezing-induced reorganization of pore structure, which in turn controls the strength evolution of warm frozen soil. These findings improve understanding of the role of unfrozen water in low-temperature soil structure and strength evolution and provide a basis for evaluating slope instability in the Ili River Valley. Full article

Penetration rate effects and partial drainage can govern piezocone (CPTu) response in intermediate permeability geomaterials, but field testing at a fixed standard rate limits systematic evaluation. This study presents the development and laboratory validation of a miniature piezocone system and testing framework to investigate rate-dependent penetration response in laboratory-prepared silty sand. Baseline dry and flooded specimens were tested using a triaxial-based configuration at penetration velocities of 9.6, 0.28, 0.10, and 0.03 mm/s, including selected holding periods for dissipation. A dedicated servo-controlled penetration system was then implemented for slurry-prepared specimens, enabling continuous constant-velocity penetration over a wider velocity range (0.004–15 mm/s). Cone resistance was interpreted using normalized net resistance (Q) and normalized velocity (V_h), and pore pressure using normalized excess pore pressure (Δu₂/σ′_v0). The results show a monotonic rate dependency, with Q increasing as V_h decreases, while Δu₂/σ′_v0 progressively decreases toward zero at intermediate-to-low V_h; at the lowest rates, pore-pressure readings were affected by instrument signal limitations. A hyperbolic-cosine backbone fitted to the normalized response provided good agreement for resistance (R² = 0.99, RMSE = 3.41) and more limited agreement for pore pressure (R² = 0.30, RMSE = 0.23). The drainage transition for the tested material occurs in an interval of approximately V_h ≈ 0.3~30. The study provides a reproducible laboratory approach—combining miniature instrumentation, controlled specimen preparation, and variable-rate penetration—to generate normalized drainage-transition trends for rate-effect investigations in intermediate geomaterials. Full article

To address the low mechanization level, high labor intensity, and severe substrate disturbance in intertidal shellfish harvesting, a vibratory harvesting method based on local vibration-induced substrate fluidization was proposed, and a vibratory harvesting device for Mactra veneriformis was developed. Bench and intertidal field tests were conducted to systematically investigate the effects of vibration frequency, vibration pressure, and vibration amplitude on substrate fluidization, clam uplift, and harvesting performance. The single-factor results showed that all three parameters significantly affected the pore water pressure ratio, substrate viscosity, uplift distance, and harvesting rate, with better fluidization obtained at 8 Hz, 30 kPa, and 25 mm. A Box–Behnken response surface design was further used to establish quadratic regression models for these responses, and all models were highly significant with a non-significant lack of fit. The optimized parameter combination was 10 Hz, 35 kPa, and 25 mm, under which the predicted pore water pressure ratio and uplift distance were 101.3% and 97.2 mm, respectively, and the substrate viscosity was 1364 Pa·s. Field tests showed that the pore water pressure ratio remained above 85.3%, viscosity decreased to 1331–2639 Pa·s, shear strength decreased by 57.2–64.9%, and the average uplift distance at 100 mm burial depth reached 80–92 mm. The results indicate that vibratory harvesting can effectively promote substrate fluidization and reduce clam uplift resistance, providing a reference for the development of low-disturbance mechanized harvesting equipment for intertidal shellfish. Full article