Under deep mining conditions, fractured rock masses are subjected to sustained high confining stress and elevated water pressure, resulting in complex seepage evolution. This study conducts triaxial seepage experiments on single-fractured sandstone to investigate the coupled effects of confining pressure, water pressure, fracture roughness (JRC), and fracture aperture under a unified stress-seepage framework representative of deep high-confined water environments. Results show that seepage flow increases linearly with water pressure but decreases nonlinearly with confining pressure, exhibiting a three-stage evolution involving elastic deformation, elasto-plastic transition, and compaction equilibrium, with a clear stabilization threshold. Elevated water pressure reduces the effective normal stress on fracture surfaces, thereby weakening fracture closure, particularly in rough fractures where asperity degradation contributes to permeability enhancement. Comparative analyses reveal that fracture roughness and aperture jointly control permeability magnitude, attenuation rate, and stabilization behavior. Quantitative relationships between stabilized permeability and key fracture parameters are established, providing a concise, parameter-based description of fracture seepage under high-stress conditions. The findings offer practical insights for predicting seepage evolution and mitigating floor water inrush risks in deep mining environments.

In this study, finite element simulations of implants with different tilting angles (15°, 30°, 45° to the axial plane) were performed to analyze the mechanical behavior and bioadaptability of four functional gradient materials (FGM) implants with complex gradients, and compared with conventional implants and monotonic FGM implants proposed in the literature. The results showed that as the tilting angle increases, the implant generates more stresses and strains in the bone, especially at the implant tilt corner contact. Notably, compared with conventional implants, nonmonotonic FGM implants (A-L-H-L, R-L-H-L), and monotonic FGM implants (R-H-L) have lower material stiffness at the base and at the tilt corners of the implant, which effectively reduces the stresses and strains in this area and reduces the risk of bone destruction. In addition, the strain intensities generated by FGM A-L-H-L and R-L-H-L implants at different tilting angles are within the range that promotes bone remodeling (1500-3000 με), which is conducive to postoperative bone recovery and long-term growth. In conclusion, the proposed nonmonotonic FGM A-L-H-L and R-L-H-L implants provide more effective stress reduction compared with high-density titanium implants and better bioadaptability compared with monotonic FGM implants. For clinical research, this study aims to obtain a gradient distribution of tilted FGM implants with better mechanical properties and biological adaptability at different tilting angles to provide a research basis for clinical and subsequent implant development.

Abstract Understanding the hydro‐mechanical behavior of faults in clay‐rich formations is essential for earthquake mechanics and underground storage applications. We conducted fully hydro‐mechanically coupled triaxial tests on preserved fault material from scaly clay sections of the Opalinus Clay formation. The faulted rock exhibits no post‐peak weakening and maintains distributed strain accommodation through the reactivation of multiple, sub‐parallel tectonic micro‐shears. The hydro‐mechanical response is stress‐dependent, transitioning from dilative shearing at lower effective consolidation stresses to constant volumetric shearing at higher effective consolidation stresses, eventually resulting in critical state conditions. Shear strength analysis revealed the absence of cohesion in the scaly clay fabric, which reduces the rock's shear strength to below the residual strength of the intact rock. These findings provide direct experimental evidence for distributed, steady‐state shearing in naturally faulted clay shale and highlight the need to incorporate fabric‐dependent behavior into models of fault mechanics.

Abstract This study systematically investigated spot heating local PWHT for pressure vessel nozzle to cylinder butt welds through integrated experimental and numerical analysis. A dual-stage local heat treatment methodology, i.e., the primary plus secondary local PWHT (PS-PWHT), was developed specifically for the nozzle to cylinder butt welds, with a systematic investigation of secondary heating parameters affecting residual stress reduction. The results demonstrate that the PS-PWHT method achieves 50-70% residual stress reduction at critical inner surface locations. Two optimized secondary heating configurations, i.e. elliptical saddle-shaped secondary heating (E-SH) and rectangular saddle-shaped secondary heating (R-SH), were established based on reverse bending moment analysis of axial/hoop heating bands. Geometric parameters were quantified with recommended secondary heating distances (WDC=2Rt and WDS=4Rt) and (2-3)t width range (where WDC and WDS are the primary and secondary heating distances for the hoop and axial heating bands, respectively. t represents wall thickness). A heating temperature range of 300-450°C was identified for secondary heating, balancing effective stress relief without material degradation and damage. The developed process control strategy demonstrates significant improvements in mitigating welding-induced residual stresses through the PS-PWHT method.

To report on a volunteer-led program supporting local healthcare providers (L-HCPs) and disaster responders after the 2024 Noto Peninsula Earthquake, focusing on its implementation and immediate outcomes. A volunteer-led initiative established by university alumni deployed medical teams to a local hospital on weekends following the earthquake, providing onsite support to relieve L-HCPs from prolonged strain. The program integrated information and communication technology (ICT) platforms to enable remote support, communication, and structured debriefing sessions for volunteers, facilitating assistance from a wider network. The project effectively sustained the local health care institution's capacity by managing diverse patient needs, including a surge in internal medical conditions. It provided essential respite, allowing local physicians crucial personal time, for which they expressed profound gratitude. Volunteer doctors reported effective stress management through the onsite and ICT-based support structure, and the initiative concluded safely without injury. The project demonstrated that combining onsite medical assistance with strategically implemented ICT effectively mitigates burnout among L-HCPs, providing essential psychological support for deployed volunteers. The findings highlight the significance of sustained recovery-phase support, professional networks, and ICT in disaster response. These experiences highlight the need for comprehensive, system-wide support strategies for all frontline personnel in future disasters.

Multi-stage cold forming is commonly used for forging fasteners and parts. This study numerically simulates the five-stage cold forming process of SCM435 alloy steel spherical joints. The five-stage cold forming process includes preparation along with centering, upsetting, twice backward extrusions over a moving punch along with upsetting to spherical shape, and piercing. The numerical simulations of cold forming are carried out using the finite element code of DEFORM-3D. The formability of the workpiece is studied, such as the forming force response, maximum forming forces, effective stress and strain distributions, and metal flow pattern. In the five-stage forming process, the effective stress and effective strain of the workpiece are significantly increased due to the large deformation in the two forming stages of backward extrusion along with upsetting to a spherical shape, and in the forming stage of piercing. The flow line distributions are also very complex, especially the flow lines in the piercing region around the inner wall of the hole are severely bent and highly compacted, eventually leading to fracture. In the fourth stage, the workpiece is secondly backward extruded along with upset, and the maximum axial forming force is the largest of the five stages. In the third stage of the firstly backward extrusion along with upset, the forming energy is the highest of the five stages due to the longer acted axial forming stroke. From the first stage to the last stage, the total maximum axial forming forces are 2,209.5 kN and the total forming energies are approximately 4.60 kJ.

Abstract Accurate prediction of depletion-induced effective stress is essential to reservoir engineering decisions across the field life cycle, influencing well instability, completion and stimulation design, production management, and geomechanical risk assessment. Although fully coupled flow–geomechanics finite-element (FE) simulations provide high-fidelity stress estimates, the associated computational cost and long runtime limit routine operational use. Therefore, this study develops an artificial neural network (ANN) proxy to rapidly predict 3D effective stress distributions driven by production-induced pore-pressure changes. The proposed workflow integrates field-scale coupled simulations with large-scale supervised learning and independent spatial validation to improve both data scale and evaluation rigor relative to many published ANN proxies. A field-scale workflow was implemented using data from 10 wells in the Buzurgan oilfield. High-resolution stress responses were generated using a fully coupled simulator (CMG-GEM 2021) and converted into supervised input–target pairs through an automated Python-based pipeline, yielding 11.26 million training samples. A compact ANN (one hidden layer with three neurons) achieved strong agreement with simulator outputs (avg. R ² = 0.94) and reproduced spatial effective-stress patterns in a structurally independent full-field case after 10 years of production, with most grid cells exhibiting deviations within ± 200 psi. The proxy reduced turnaround time from approximately hours per coupled FE run to minutes per prediction, enabling near real-time stress screening and sensitivity analysis for operational decision-making.

This paper examines the applicability of the fracture forming limits (FFLs) derived from conventional monotonic upset compression tests for assessing the formability of non-monotonic strain loading paths. The work uses a simple test specimen subjected to various non-monotonic deformation histories, and combines experimental force measurements, digital image correlation, finite element analysis, and scanning electron microscopy (SEM) to characterize strain loading paths and crack opening mechanisms under varying testing parameters. Results demonstrate that non-monotonic strain loading paths can result in fracture strains that differ from those obtained through conventional monotonic bulk formability tests in the effective strain versus stress triaxiality space, depending on the considerations made in the transition between different loading stages. Consequently, reliance on monotonic test data may lead to inaccurate predictions of cracking in multi-stage industrial bulk forming processes.

This paper develops a nonlinear strain wedge (SW) model for analyzing laterally loaded piles installed in the proximity of sandy slopes, with consideration of slope surface deformation. This model is first developed for piles at the slope crest, characterizing the slope surface deformation to calculate soil strain and incorporating the reduction in effective vertical stress. Furthermore, this model provides a smooth transition between piles located at varying distances from the slope and those at the crest, accounting for varying near-slope distances. Thus, a comprehensive model is established that considers the influence of slope effects on pile–soil interactions. Predictions from the proposed model show good agreement with a series of centrifuge tests and three model tests. Finally, the effects of applied load, slope angle, near-slope distance, Poisson’s ratio, and friction angle on the pile response, slope surface deformation, and soil deformation are discussed.

Magmatic and clastic sills are common elements in rift sedimentary basins worldwide. Many documented magmatic sills are based on seismic interpretations, which, owing to limited resolution and imaging constraints, provide only partial insights into their emplacement mechanisms and magma dynamics. This contribution presents detailed field results from a 1.3-km-long coastal outcrop of a Cretaceous (Albian) igneous sill occurring in rifted sediments of the western Pyrenees. This sheet, previously interpreted as a lava flow, shows many diagnostic features that indicate it intruded in organic-rich wet sediments, constituting a sill (the Armintza Sill). Detailed mapping assisted by drone imagery of the sill, host succession, and preexisting faults shows that the sill is composed of magma fingers arranged in a fault-block pattern. Concordant magma fingers were emplaced by thermal fluidization of host sediment due to flash boiling of pore waters, aided by contact metamorphism-induced fluid generation and overpressuring. We suggest that fluid overpressure also caused transient uplift of the thin overburden, leading to the nucleation of inelastic damage along the preexisting faults, facilitating magma ascent up fault. Progressive up-fault verticalization of the σ3 orientation and reduction of inelastic damage likely created a partial barrier near the upper part of the faults, leading to significant flow thickening, deceleration, and diversion. The similarity between these features of the Armintza Sill and those observed in lava flows that interacted with topographic obstacles is interpreted to be the result of near-zero effective stresses in the host sediments.

Abstract Background With the acceleration of urbanization, traffic congestion is becoming increasingly severe. As an important component of urban transportation system, the mental health status of bus drivers directly affects the service quality and driving safety of public transportation. Bus drivers face a complex and ever-changing work environment, including road congestion, passenger emotional fluctuations, and other challenges, which bring significant psychological pressure to drivers. For example, drivers who are exposed to traffic congestion for a long time may experience significant psychological pressure, leading to mental health problems. Therefore, this study explores the impact of transportation environment on the mental health of bus drivers, providing scientific basis for improving their working environment and mental health. Methods A study was conducted on 68 bus drivers to investigate and analyze their mental health. Firstly, collect the basic information of the driver, including age, gender, years of work experience, daily working hours, etc. Afterwards, descriptive statistical analysis will be conducted on the basic information of drivers, and multivariate regression analysis will be used to evaluate the factors affecting the psychological health of drivers. Results The survey results showed that out of 68 respondents, a total of 55 experienced physiological reactions to work stress. Among them, 15 people experienced fatigue and decreased energy, 10 people had sleep disorders, 14 people had digestive system problems, and 16 people had decreased immune system function. Among the 68 surveyed individuals, a total of 47 experienced psychological reactions of work stress. Among them, a total of 12 people showed symptoms of anxiety, 11 people showed problems with attention and memory, 10 people showed symptoms of depression, and 14 people showed symptoms of decreased self-efficacy. Finally, in terms of behavioral response, 10 individuals exhibited abnormal driving behavior, 11 exhibited changes in work behavior, 12 exhibited changes in healthy habits, and 10 exhibited avoidance behavior. Meanwhile, the multivariate analysis results showed that the standardized Beta coefficient of the impact of factors such as traffic problems and work environment on drivers' work stress response was 0.108, with a t-value of 3.07, p=.002. This indicating that work environment and traffic issues have a significant positive impact on drivers' work stress response. Discussion The experimental results show that nearly 30% of the surveyed bus drivers have symptoms of anxiety and depression, and most drivers have physiological, psychological, and behavioral reactions to work stress. Among them, factors such as traffic problems and working environment have a significant negative impact on the mental health of bus drivers, increasing the risk of psychological stress, anxiety, and depression. In order to improve the mental health status of drivers, research suggests using intelligent transportation systems, traffic signal optimization, and other means to reduce traffic congestion and alleviate drivers' work pressure. At the same time, provide drivers with mental health education and counseling services to help them master effective stress management and coping strategies. The limitation of the study is that it did not explore the causal relationship between stress influencing factors. Future research will further demonstrate the influencing factors of driver mental health and improve the longitudinal study design.

Abstract Frequency‐dependent seismic velocity variations (dv/v) provide depth‐resolved constraints on aquifer behavior under groundwater fluctuations. We analyze 17 years of dv/v time series from ambient noise interferometry in the Chiang Mai Basin, Thailand, and observe contrasting dv/v behavior below and above 1 Hz. By integrating GPS, meteorological, and GWL data with poroelastic stress modeling, we disentangle the contemporaneous effects of pore saturation, pore pressure change, and mass loading. Our results show that the pore saturation and pore pressure change jointly influence shallow aquifer layers, while mass loading governs deeper responses. This depth‐dependent interplay highlights the importance of effective stress modeling in interpreting dv/v patterns and the potential of passive seismic techniques to monitor layered hydromechanical processes in aquifer systems.

Abstract This paper reviews recent work on energy-based methodologies for estimating pore water pressure rise and the timing of initial soil liquefaction. Unlike stress-based methods, energy-based approaches use a scalar, cumulative parameter—making them well suited to modeling pore pressure buildup and the timing of liquefaction onset. The rise in pore pressure and onset of liquefaction can be estimated by summing cumulative dissipated hysteretic strain energy normalized by effective stress, which correlates strongly with the pore-pressure ratio $${r}_{u}$$ . As such,, normalized energy is a complex parameter that combines the demand and capacity sides of the liquefaction problem into one term. Energy dissipated beyond the liquefaction boundary maintains $${r}_{u}=1.0$$ , and likely is correlated with the potentially large shear and volumetric strains associated with liquefaction damage. However, one practical challenge of applying the method is that it requires empirical hysteretic relationships between normalized cumulative energy and excess pore pressure ratio, that are difficult to obtain in the laboratory and almost never available in the field. Proxy models for dissipated work—using Arias Intensity, Cumulative Absolute Velocity (CAV), and soil parameters, relative density or the state parameter of Been and Jeffries (1985)—appear to be the most practical path forward. However, these parameters are hampered by their elevated predictive uncertainties. The key benefit of the scalar and cumulative nature of energy-based methods are that they lead to improved estimation of liquefaction timing. Therefore, we can use just the the post-initial liquefaction time history to correlate with shear and volumetric strains. Three independent methods are currently used: the hysteretic strain-energy method, the Spectral Energy Ratio (SER) method, and Arias Intensity timing. These approaches aim to link total energy demand (Arias Intensity) to partial absorbed work (hysteretic strain energy). Parallel research investigates shear and volumetric strains before, during, and after $${r}_{u}=1.0$$ . Liquefaction timing estimates based on Arias Intensity and SER can recalibrate soil models for $$G/{G}_{max}$$ , energy absorption, and pore pressure rise. Future work will establish relationships between hysteretic strain energy, Arias Intensity, and CAV with field penetration resistance, relative density, and initial shear stress. If successful, simplified energy demand parameters could assess liquefaction potential and act as proxies for dissipated work. Ultimately, well-documented case histories and robust proxy models will provide the foundation for energy-based, performance-oriented liquefaction assessment methods.

A closed-form effective stress limit plasticity solution for assessing the peak effective friction angle (φ’) in soils from piezocone penetration tests (CPTU) was developed by the Norwegian Institute of Technology (NTH) over five decades ago with the versatility that it could address all soils, including clays, silts, sands, and mixed soil types. The NTH solution utilizes normalized cone resistance (Q), pore pressure ratio Bq, and plastification angle β. A recently compiled database on 32 well-documented sands and silty sands that were subjected to in-situ CPTU soundings and field sampling with laboratory triaxial compression tests (n = 71) permits a look at the verification and validation of the NTH solution for evaluating φ' in granular soils of low compressibility. The dataset is comprised mainly of sandy soils that are quartzitic to siliceous, albeit more complex mineralogies are also found. It is found that the theoretical plastification angle (β) is directly analogous to the state parameter of sands (Ψ). Both parameters are indicators on the behavior of sand to either be contractive or dilative. Relationships linking β in terms of Ψ are derived using six available CPTU screening methods for the state parameter, Ψ. Results from the triaxial compression test database are used to validate the evaluation of φ’ from the NTH solution utilizing all three readings of the CPTU: qt, fs, and u2.

ABSTRACT The stress‐induced initiation of pre‐existing natural fractures (NFs) constitutes a critical mechanism in forming complex fracture networks during hydraulic fracturing. Previous studies have largely overlooked this process, resulting in significant discrepancies between simulated and actual fracture complexity. To address this gap, we developed a numerical model based on the discontinuous displacement method to simulate the evolution of complex fracture networks. Simulation results reveal that pre‐existing NFs can initiate under both intersecting and non‐intersecting conditions with hydraulic fracture (HF). When the minimum horizontal effective stress exceeds 2 MPa, their propagation becomes significantly inhibited. As the induced stress field evolves dynamically with HF propagation, the initiation and growth of isolated NFs exhibit time‐dependent characteristics. Complex fracture networks cannot be efficiently created by hydraulic‐natural fracture intersections alone. This study provides new physical insights into the evolution of HF networks and advances numerical simulation methodologies. The findings establish a theoretical foundation for precise fracture network control in field applications.

Abstract. To improve our understanding of firn compaction and deformation processes, constant-load compressive creep tests were performed on specimens from a Summit, Greenland (72°35′ N, 38°25′ W) firn core that was extracted in June 2017. Cylindrical specimens were tested at temperatures of −5, −18 and −30 °C from depths of 20, 40 and 60 m at stresses of 0.21, 0.32 and 0.43 MPa, respectively. The microstructures were characterized before and after creep using both X-ray micro-computed tomography (micro-CT) and thin sections viewed between optical crossed polarizers. The results of these experiments comprise a novel data set on the creep of firn at three depths of a firn column at three different temperatures, providing useful calibration data for firn model development. Examining the resulting strain vs. time and strain vs. strain rate curves from the creep tests revealed the following notable features. First, the time exponent k was found to be 0.34–0.69 during transient creep, which is greater than the 0.33 usually observed in fully-dense ice. Second, the strain rate minimum (SRmin) in secondary creep occurred at a greater strain from specimens with lower density and at higher temperatures. Third, tertiary creep occurred more easily for the lower-density specimens at greater effective stresses and higher temperatures, where strain softening is primarily due to recrystallization. Fourth, the SRmin is a function of the temperature for a given firn density. Lastly, we developed empirical equations for inferring the SRmin, as it is difficult to measure during creep at low temperatures. The creep behaviors of polar firn, being essentially different from full-density ice, imply that firn densification is an indispensable process within the snow-to-ice transition, particularly firn deformation at different temperatures connected to a changing climate.

The anatomy and mechanical strength of aortic valve leaflets are critical determinants of their biomechanical behavior and long-term structural integrity. The embryonic developmental period, when valves are forming, is critical to establish baseline leaflet properties. However, fetal stages of valve development, when valve leaflets are still forming and remodeling, are not well understood. The goal of this study is to investigate the biomechanical stress and deformation modes of developing valve leaflets during systole, and how leaflet biomechanics are affected by anatomy and material properties. To this end, the study employs a parametric approach to model the leaflet anatomy of an HH40 chick embryo, used here as a model of fetal cardiac development. To perform biomechanical analysis, a pressure profile derived from in ovo Doppler ultrasound measurements was applied, and an Ogden hyperelastic material model was employed following a sensitivity analysis. To determine the effect of valve anatomy on leaflet tissue deformation and stresses, we changed the leaflet midline curve (belly curve) from its native curvature to a linear profile and quantified biomechanical responses. Our analysis revealed a strong decrease in average leaflet effective stress as the belly curvature was shifted towards a linear profile. However, this reduction in average stress was at the expense of a biomechanical trade-off. The shift induced a progressive localization of stress concentration at the leaflet tips and commissures, and a distinct bending deformation mode at the tip under peak load. Our findings demonstrate that while the belly curve of the leaflet modulates tissue stress during valve opening, a low-stress anatomy does not align with hemodynamic performance. This work characterizes competing leaflet biomechanical responses (stress reduction versus failure modes) that shape valve leaflet formation, providing fundamental insights into developmental valve biomechanics.

During oilfield injection and production operations, fluid injection and withdrawal can significantly alter the stress state around faults, potentially triggering fault reactivation and even seismic events, which has become a focal issue in both industry and academia. In this study, based on fluid–solid coupling theory and the rate-and-state friction constitutive model, a mechanical framework was developed to evaluate fault shear slip behavior induced by injection–production activities. Numerical simulations were conducted using COMSOL Multiphysics to systematically investigate the effects of injection–production rate, operational schemes, well placement, reservoir permeability, and fault dip angle on fault stability. The results indicate that higher injection–production rates, non-steady operational schemes, injection wells located closer to faults, production wells farther from faults, lower fault core permeability, and larger fault dip angles can significantly enhance fluid pressure buildup and effective stress variations within the fault core zone. These processes lead to pronounced increases in Coulomb Failure Stress (CFS) and reductions in critical stiffness, thereby elevating the risk of fault instability and slip. Overall, the findings suggest that optimizing injection–production parameters and well placement can effectively mitigate the likelihood of fault reactivation. This study provides theoretical insights into the mechanisms of injection–production-induced fault slip and offers valuable references for safe oilfield operations and seismic risk assessment.

Solid-state recycling of magnesium alloys relies on effective pre-compaction to convert loose machining chips into dense precursors suitable for downstream processing. This study investigates the consolidation mechanisms of AZ80 Mg chips containing residual water-based lubricants, compacted in a single-action hydraulic press without prior cleaning. The compaction pressure, holding time, and pressure evolution were analyzed to determine their influence on briquette quality. The findings demonstrated that holding time, rather than peak pressure, was the governing factor for densification. Extended holding promoted internal stress redistribution and geometric adaptation, facilitating pore collapse and yielding green densities of ~ 91-92% with uniform axial distribution, while short holding times limited effective stress transmission, resulting in heterogeneous density gradients. Microstructural analysis revealed that while native oxide barriers persisted, preventing full metallurgical bonding, extended holding achieved sub-micron interfacial spacing and effective geometric closure. Hardness mapping indicated that shorter holding times retained higher hardness values (~ 110-116 HV), consistent with high localized work hardening and incomplete stress redistribution. In addition, compression tests revealed that stiffness was governed by interfacial integrity rather than bulk density. Therefore, samples with superior geometric sealing exhibited significantly higher stiffness (2964 MPa) compared to denser samples with poorer interfacial locking. These results indicate that optimizing interfacial contact through load maintenance is critical for producing stable briquettes, providing a pathway for robust solid-state recycling of AZ80 alloys.

Against the backdrop of increasingly fierce market competition and accelerating work rhythms, the work and life pressures faced by employees continue to rise, and mental health issues have gradually become key factors affecting enterprise development and employee well-being. Effective stress management and a sound psychological support system are not only important foundations for ensuring employees’ physical and mental health but also inherent requirements for improving enterprise organizational efficiency and enhancing core competitiveness. Based on this, this paper conducts research on employee stress management and psychological support, elaborates on the existing problems in current employee stress management and psychological support, analyzes the important value of carrying out related work, and then puts forward targeted countermeasures, providing useful references for enterprises to improve their employee stress management and psychological support levels.