Search Results (80)

This study investigates the mechanical behavior and safety performance of buried natural gas pipelines crossing seismically active fault zones and liquefaction-prone areas, with particular application to the China–Russia East-Route Natural Gas Pipeline. The research combines experimental testing, numerical simulation, and machine learning to develop an advanced framework for pipeline safety assessment under seismic loading conditions. A series of large-scale pipe–soil interaction experiments were conducted under seismic-frequency cyclic loading, leading to the development of a modified soil spring model that accurately captures the nonlinear soil-resistance characteristics during seismic events. Unlike prior studies focusing on static or specific seismic conditions, this work uniquely integrates real cyclic loading test data to develop a frequency-dependent soil spring model, significantly enhancing the physical basis for dynamic soil–pipeline interaction simulation. Finite element analyses were systematically performed to evaluate pipeline response under liquefaction-induced ground displacement, considering key influencing factors including liquefaction zone length, seismic wave frequency content, operational pressure, and pipe wall thickness. An innovative machine learning-based predictive model was developed by integrating LightGBM, XGBoost, and CatBoost algorithms, achieving remarkable prediction accuracy for pipeline strain (R² > 0.999, MAPE < 1%). This high accuracy represents a significant improvement over conventional analytical methods and enables rapid safety assessment. The findings provide robust theoretical support for pipeline routing and seismic design in high-risk zones, enhancing the safety and reliability of energy infrastructure. Full article

Ammonia is increasingly recognised as a promising carbon-free fuel and hydrogen carrier due to its high hydrogen content, ease of liquefaction, and existing global infrastructure. However, its direct utilisation in combustion systems poses significant challenges, including low flame speed, high ignition temperature, and the formation of nitrogen oxides (NO_X). This review explores catalytic ammonia cracking as a viable method to enhance combustion through in situ hydrogen production. It evaluates traditional catalytic burner designs originally developed for hydrocarbon fuels and assesses their adaptability for ammonia-based applications. Special attention is given to ruthenium- and nickel-based catalysts supported on various oxides and nanostructured materials, evaluating their ammonia conversion efficiency, resistance to sintering, and thermal stability. The impact of the main operational parameters, including reaction temperature and gas hourly space velocity (GHSV), is also discussed. Strategies for combining partial ammonia cracking with stable combustion are studied, with practical issues such as catalyst degradation, NO_X regulation, and system scalability. The analysis highlights recent advancements in structural catalyst support, which have potential for industrial-scale application. This review aims to provide future development of low-emission, high-efficiency catalytic burner systems and advance ammonia’s role in next-generation hydrogen energy technologies. Full article

Case histories have shown that the liquefaction behavior of soils can differ depending on the pre-seismic history of sites. Assessing the shear modulus in soils subjected to seismic events is critical for advancing the fundamental understanding of soil behavior and enhancing the accuracy of soil modeling applications. This paper aims to study the effect of small and large pre-shaking sequences on the liquefaction resistance and shear modulus of sand through shaking table tests. The experimental results indicated that small shakings increase liquefaction resistance and shear modulus. Although large shakings leading to liquefaction cause significant densification, they significantly reduce the liquefaction resistance and shear modulus of sand at shallow depths due to the upward water flow during excess pore water pressure dissipation. The high upward flow of water during liquefaction changes the soil structure and increases the horizontal displacement of densified soil in the subsequent shaking. The amplification factor of acceleration was found to be primarily influenced by the excess pore water pressure generated in the soil instead of its relative density at the start of shaking. This paper presents the variations in Ru with shear strain and the relationship between a normalized shear modulus and shear strain considering the pre-shaking history of sand for shallow depths. Full article

Electrolysis desaturation has emerged as an innovative technique to mitigate liquefaction risk by reducing soil saturation in liquefiable foundations. This study evaluated the effectiveness of horizontal electrolysis on calcareous sandy foundations in marine environments by employing 35‰ NaCl solution as pore fluid under different current intensities (1A, 2A, and 4A). Experimental results demonstrated that hydrogen gas was generated at the cathode, while chlorine gas was produced at the anode, with peak gas retention rates of 100%, 90.83%, and 63.26% for 1A; 97.61%, 79.04%, and 60.94% for 2A; and 95.37%, 48.49%, and 42.81% for 4A over three electrolysis cycles. Three key findings emerged from our investigation: First, the resistivity of calcareous sand displayed a three-stage variation pattern, primarily governed by temperature and gas content evolution. Second, the temperature-corrected resistivity model provided reliable saturation data, revealing that electrode-adjacent soil layers exhibited significantly greater saturation reduction compared to intermediate layers. The average saturation variation during a single electrolysis cycle reached 3.2%, 2.6%, and 4.4% for 1A, 2A, and 4A, respectively, in the soil layers near the electrodes, compared to 2.1%, 1.7%, and 3.3% in the middle soil layers under the same current intensities. Third, upon stopping electrolysis, gas redistribution led to decreased saturation in upper soil layers, with lower current intensities more effective in retaining gases within the soil matrix. Based on these findings, an electrolytic influence coefficient for calcareous sand applicable to Archie’s formulation is proposed. This study enhances the understanding of the mechanism of electrolysis desaturation and provides a theoretical basis for the effectiveness of electrolysis desaturation on calcareous sand foundations. Full article

Liquefaction and earthquake damage to coral sand sites can cause engineering structure failure. Both testing and analyzing the seismic response characteristics of pile groups on coral sand sites are highly important for the seismic design of engineering structures. To address the lack of research on the seismic dynamic response of group pile foundations in coral sand sites, this study analyzes the characteristics of the seismic dynamic response of vertical and batter pile foundations for bridges in coral sand liquefaction foundations via the shaking table model test and investigates the variation patterns of acceleration, excess pore water pressure (EPWP), and the bending moment and displacement of foundations, soil, and superstructures under different vibration intensities. Results show that the excitation wave type significantly affects liquefaction: at 0.1 g of peak acceleration, only high-frequency sine wave tests liquefied, with small EPWP ratios, while at 0.2 g, all tests liquefied. Vertical pile foundations had lower soil acceleration than batter piles due to differences in bearing mechanisms. Before liquefaction, batter piles had smaller EPWP ratios but experienced greater bending moments under the same horizontal force. Overall, batter piles showed higher dynamic stability and anti-tilt capabilities but endured larger bending moments compared to vertical piles in coral sand foundations. In conclusion, batter pile foundations demonstrate superior seismic performance in coral sand sites, offering enhanced stability and resistance to liquefaction-induced failures. Full article

Extensive research has been conducted on the application of pyrolysis and hydrothermal carbonization (HTC) biochar for soil amendment. However, hydrochar from hydrothermal liquefaction (HTL) has received little attention regarding its potential for such application. This research paper aims to fill this knowledge gap. In this study, corn stover-derived hydrochar from HTL at 280 °C was characterized using suitable analytical techniques to determine the functional groups, specific surface area, and morphology. The effects of HTL hydrochar on water holding capacity (WHC) and water retention of sandy loam soil and the resistance to biodegradation were also studied. The BET surface area of hydrochar was found to be 27.6 m²/g. The hydrochar particles are micro-sized stacking of nanometer-thick foliates. The hydrochar-amended soil consistently showed better WHC ranging from 50 to 55% compared to the unamended soil of 48%. A similar trend was observed for water retention over a period of four days. No notable biodegradation was observed for the hydrochar over a period of 106 days in wet soil at the ambient temperature. Overall, these results demonstrate the potential of HTL hydrochar as a valuable soil amendment to enhance agriculture sustainability. Full article

In this paper, alumina-modified wood liquefaction (AL-WP) was prepared by blending nano-alumina (Al₂O₃) into wood liquefaction phenolic resin (WP) using a co-blending method. Alumina-modified wood liquefaction protofilament fiber (AL-WPF) was obtained by melt-spinning, curing, and thermo-curing processes, which were followed by carbonization to obtain alumina-modified wood liquefaction carbon fiber (AL-WCF). This paper focuses on the enhancement effect of nano-alumina doping on the mechanical properties and heat resistance of wood liquefaction carbon fiber (WCF), explores the evolution of graphite microcrystalline structure during the high-temperature carbonization process, and optimizes the curing conditions of AL-WPF. The results showed that the introduction of Al₂O₃ significantly improved the mechanical properties and heat resistance of carbon fibers. When 1.5% Al₂O₃ was doped and carbonized at 1000 °C, the tensile strength of AL-WCF was increased from 33.78 MPa to 95.74 MPa, there was an enhancement of 183%, its residual carbon rate could reach 79.2%, which was better than that of the undoped wood liquefaction (WCF), and it exhibited a more substantial heat-resistant property. In addition, the best curing process for alumina nanoparticle wood liquefiers was obtained by optimizing the curing conditions: hydrochloric acid concentration of 16%, formaldehyde concentration of 18.5%, temperature increase rate of 15 °C/min, holding time of 3 h, and holding temperature of 100 °C. These studies provide a theoretical basis and technical support for developing and applying carbon fibers from alumina-modified wood liquefiers. Full article

Electrolyzed acidic water (EAW) contains hypochlorous acid as its active compound, which is a potent antimicrobial. It was encapsulated in polymeric coatings and applied to the surface of eggs. The antimicrobial activity and the ability to extend the shelf life of eggs at ambient temperature for 45 days were evaluated, by physical, microbiological, and sensory analyses. The analysis also included the evaluation of mechanical, thermal, and crystallinity properties and the interaction between the coating components and the eggshell. The results showed that eggs from young, middle-aged, and adult hens, encapsulated and coated with EAW, hydroxypropyl methylcellulose, polyvinyl alcohol, and chitosan, gained resistance and a glossy appearance. The thickness of the coating was 2.9 µm for young and adult hens’ eggs and 2.60 µm for those of old hens, as observed by SEM. Shelf life was extended to 45 days under refrigeration and more than 30 days at ambient temperature. Coated eggs were acceptable for 85% of the panelists compared to 57% acceptance of non-coated eggs. The encapsulation and coating with EAW as an antimicrobial agent improved the surface protection of commercial eggs, reduced albumen liquefaction, and maintained quality by acting as a barrier against air, thereby preserving sensory characteristics. Full article

At least 32 case histories have shown that liquefaction can occur in gravelly soils (both natural deposits and manmade reclamations) during severe earthquakes, causing large ground deformations and severe damage to civil infrastructures. Gravelly soils, however, pose major challenges in geotechnical earthquake engineering in terms of assessing their deformation characteristics and potential for liquefaction. In this study, aimed at providing valuable insights into this important topic, a series of isotropically consolidated undrained cyclic triaxial tests were carried out on selected sand–gravel mixtures (SGMs) with varying degrees of gravel content (G_c) and relative density (D_r). The pore water pressure generation and liquefaction resistance were examined and then further scrutinized using an energy-based method (EBM) for liquefaction assessment. It is shown that the rate of pore water pressure development is influenced by the cyclic resistance ratio (CSR), G_c and D_r of SGMs. However, a unique correlation exists between the pore water pressure ratio and cumulative normalized dissipated energy during liquefaction. Furthermore, the cumulative normalized energy is a promising parameter to describe the cyclic resistance ratio (CRR) of gravelly soils at various post-liquefaction axial strain levels, considering the combined effects of G_c and D_r on the liquefaction resistance. Full article

The air injection method serves as a liquefaction mitigation technique to improve the liquefaction resistance of the foundations by decreasing the degree of saturation. To investigate the desaturation effect of this technique in various soil strata of the foundation, thin plate model tests were conducted, considering the impacts of gradation and relative density, to visualize the air migration process and distribution. The findings reveal the following: (1) The air migration process, delineated by air injection parameters, comprises four distinct phases, with stages II and III notably influenced by the pore structure; (2) air migration is governed by the pore throat dimensions, particle arrangement, and connectivity within the pore structure, exhibiting two predominant patterns: channel flow, primarily driven by inertial forces, and chamber flow, predominantly influenced by viscous and capillary forces; (3) referring to the air injection port, the gas phase distribution within the sand samples is consistent in the horizontal direction but not in the vertical direction. The concentration area and uniformity of the gas phase distribution are controlled by the pore structure. These results suggest potential enhancements in the positioning of air injection ports within complex soil layers, as well as improvements in the construction process, both aimed at optimizing the desaturation effect. Full article

Pumiceous deposits, commonly found in volcanic regions such as the Ring of Fire and the Alpide Belt, pose significant engineering challenges due to the presence of highly crushable and compressible grains in their matrix. These deposits exhibit complex geotechnical characteristics and are frequently linked to natural events like landslides and earthquakes. Research in countries such as New Zealand, Japan, Indonesia, Italy, and Central and South America aims to better understand the mechanical behaviour of these materials. Key influencing factors include geological properties, microstructure, shearing characteristics, and the impact of particle breakage. Comparative studies have identified similarities in specific gravity, void ratio, particle size distribution, and shearing mechanisms across regions. However, notable differences appear when compared to hard-grained sands including higher void ratios, variations in relative density due to crushable grains, and increased angularity. Some responses of pumiceous deposits, such as strain softening, liquefaction resistance depending on gradation, and apparent cohesion from grain interlocking, mirror those of hard sands; however, particle crushing plays a crucial role in the behaviour. Accurate numerical modelling, which simulates crushing under different conditions, is essential for characterising pumiceous deposits in situ, providing engineers with a better understanding of these materials across diverse site conditions. Full article

In additive manufacturing, controlling hot cracking in non-weldable nickel-based superalloys poses a significant challenge for forming complex components. This study introduces a multiple preheating process for the forming surface in electron beam powder bed fusion (EB-PBF), employing a dual-band infrared surface temperature measurement technique instead of the conventional base plate thermocouple method. This new approach reduces the temperature drop during forming, decreasing surface cooling by 28.6% compared to traditional methods. Additionally, the precipitation of carbides and borides is reduced by 38.5% and 80.1%, respectively, lowering the sensitivity to liquefaction cracking. This technique enables crack-free forming at a lower powder bed preheating temperature (1000 °C), thereby improving the powder recycling rate by minimizing powder sintering. Microstructural analysis confirms that this method reduces low-melting eutectic formation and alleviates liquefaction cracking at high-angle grain boundaries caused by thermal cycling. Consequently, crack-free IN738 specimens with high-temperature durability were successfully achieved, providing a promising approach for the EB-PBF fabrication of crack-resistant IN738 components. Full article

This paper examines how smart cities can address land subsidence and liquefaction in the context of rapid urbanization in Japan. Since the 1960s, liquefaction has been an important topic in geotechnical engineering, and extensive efforts have been made to evaluate soil resistance to liquefaction. Currently, there is a lack of machine learning applications in smart cities that specifically target geological hazards. This study aims to develop a high-performance prediction model for estimating the depth of the bearing layer, thereby improving the accuracy of geotechnical investigations. The model was developed using actual survey data from 433 points in Setagaya-ku, Tokyo, by applying two machine learning techniques: artificial neural networks (ANNs) and bagging. The results indicate that machine learning offers significant advantages in predicting the depth of the bearing layer. Furthermore, the prediction performance of ensemble learning improved by about 20% compared to ANNs. Both interdisciplinary approaches contribute to risk prediction and mitigation, thereby promoting sustainable urban development and underscoring the potential of future smart cities. Full article

Under traffic load, earthquake load, and wave load, saturated sand foundation is prone to liquefaction, and foundation reinforcement is the key measure to improve its stability and liquefaction resistance. Traditional foundation treatment methods have many problems, such as high cost, long construction period, and environmental pollution. As a new solidification method, enzyme-induced calcium carbonate precipitation (EICP) technology has the advantages of economy, environmental protection, and durability. Through a triaxial consolidated undrained shear test under cyclic loading, the impacts of confining pressure (σ₃), cementation number (P_c), cyclic stress ratio (CSR), initial dry density (ρ_d), and vibration frequency (f) on the development law of pore water pressure of EICP-solidified sand are analyzed and then a pore water pressure model suitable for EICP-solidified sand is established. The result shows that as σ₃ and CSR increase, the rise rate of pore water pressure of solidified sand gradually accelerates, and with a lower vibration number required for liquefaction, the anti-liquefaction ability of solidified sand gradually weakens. However, as P_c, ρ_d, and f rise, the increase rate of pore water pressure of solidified sand gradually lowers, the vibration number required for liquefaction increases correspondingly, and its liquefaction resistance gradually increases. The test results are highly consistent with the predictive results, which show that the three-parameter unified pore water pressure model is suitable for describing the development law of A-type and B-type pore water pressure of EICP-solidified sand at the same time. The study results provide essential reference value and scientific significance in guidance for preventing sand foundations from liquefying. Full article

Post-earthquake investigations have shown that piles in liquefiable soils are highly susceptible to damage, especially in sloping sites. This study examines the seismic performance of pile groups with lateral spreading through advanced numerical modeling. A three-dimensional finite element model, validated against large-scale shaking table test results, is implemented to capture the key mechanisms driving the dynamic response of pile groups under both inertial and kinematic loading conditions. Parametric seismic response analyses are conducted to compare the behavior of batter and vertical piles under varying ground motion intensities. The results indicate that batter piles experience increased axial compressive and tensile forces compared to vertical piles, up to 70% and 20%, respectively. However, batter piles provide enhanced lateral stiffness and shear resistance compared to vertical piles, reducing horizontal displacements by up to 20% and tilting the cap by 85% under strong ground motion. The results demonstrate that batter piles not only enhance the overall seismic stability of the structure but also mitigate the risk of liquefaction-induced lateral spreading in the near-field through pile-pinning effects. While vertical piles are more commonly used in practice, the distinct advantages of batter piles for seismic stability highlighted in this study may encourage using more advanced numerical modeling in engineering projects. Full article