Search Results (195)

The safety of waterproof joints in concrete-faced rockfill dams (CFRDs) founded on deep overburden was determined during construction, impoundment, and sedimentation periods, employing the flexible FEM-NSBPFEM coupled method. Through eleven numerical scenarios, critical deformation zones are identified, and the effects of upper soil loads (upstream weighting and sedimentation) and cutoff wall design plans on the key joint between the connecting plate and the cutoff wall (J1) are systematically evaluated. The principal findings reveal that: (1) Joint deformation is dominated by vertical shear, primarily localized at J1, with the shear deformation at J1 reaching approximately 15 cm when the height of the upper soil load reaches 40 m. (2) Upper soil loads exert a greater influence on J1 shear deformation than hydrostatic pressure. (3) Increasing sedimentation loads cause J1 shear deformation to initially mirror impoundment trends before undergoing a sharp surge, and the effect is exacerbated by higher upstream weighting loads. (4) Shear deformation varies markedly between closed and suspended cutoff walls, whereas variations among different suspended wall designs are smaller. Based on these mechanical insights, two optimization schemes for the impermeable system are proposed, effectively constraining joint shear and opening displacements to within 4 cm. These findings provide critical guidance for the reliability analysis and design optimization of CFRD impermeable systems in deep overburden environments. Full article

Right ventricular pressure overloading [RVPO] with secondary maladaptive RV remodeling and progressive myocardial dysfunction in patients with pulmonary hypertension associated with left-sided heart diseases [PH-LHDs] and in those with pulmonary arterial hypertension [PAH] still remains one of the most complex challenges in cardio-pulmonary medicine. Despite the advances in the optimization of diagnostic tools and the expansion of treatment options, there is still a great need for further research to gain a better understanding of the major pathophysiological mechanisms involved in both the RV responses to PO and to find new possibilities to stop the progression of the alterations inside the pulmonary arterial circulation [PAC]. This article summarizes current knowledge about the particularities of the RV structural and functional responses to abnormal PO and also provides an overview of the benefits and limitations of the currently available tools for clinical evaluations of the RV adaptability to high afterload. A major focus of this review relates to the possibilities for obtaining evidence about the existence of a still remaining adaptability to a normal afterload in an over-burdened RV, in case of abolition of the pathological PO and, in this regard, to also evaluate the clinical usefulness of the RV adaptability estimation for certain critical therapeutic decisions. Among the most important conclusions of this updated overview are: 1. Whereas single parameters are insufficiently reliable for the evaluation of RV dysfunction and for predictions of its prognostic relevance across the whole spectrum of RVPO, properly selected and integrated multiparametric approaches had meanwhile unequivocally proved that they can usually become sufficiently reliable. 2. Multiparametric approaches can substantially improve the prediction of a preserved RV responsiveness to the abolition of its steady PO by reversal of RV maladaptive remodeling and by the normalization of RV pump function. Such a prediction, which can be decisive for therapeutic decision-making especially in candidates for ventricular assist device [LVAD] implantation or thoracic organ transplantation, can have a crucial impact on patient survival. 3. The complex and temporally highly variable interactions between certain structural and functional changes in both the PAC and in the hemodynamic overloaded right-sided heart, as well as between the two ventricles, can often hamper the interpretation of certain changes in the measured parameters and even relevantly alter their reliability. Additionally, the progressive aggravation of a secondary tricuspid regurgitation [TR] has a particularly high negative (often also misleading) impact on the diagnostic and prognostic relevance of RVPO evaluations. Full article

The demand for lead–zinc–antimony ore resources in China has increased steadily, while shallow deposits are approaching depletion, leading to intensified exploration for deep, concealed orebodies. Electro-geochemical surveys, as a penetrative geochemical exploration technique, are particularly effective in areas with thick overburden. In this study, the Bancai area in Hechi, Guangxi, was selected to evaluate the applicability of this method for concealed mineral exploration. Feasibility testing was conducted along the A4 profile over an engineering-controlled orebody. Distinct electro-geochemical anomalies were identified directly above the known orebody, showing strong spatial correspondence and favorable ore-indicating characteristics, confirming the effectiveness of the method in the study area. Based on the deposit’s geological characteristics, prospecting indicators were established by integrating geological features, electro-geochemical responses, and wall-rock alteration. A geological electro-geochemical prospecting model was constructed for the Bancai mining area and applied for deep exploration of the Bancai B block. By analyzing the spatial distribution of electro-geochemical anomalies and integrating geological conditions, mineralization potential, and related factors, three prospective target areas were delineated to provide guidance for subsequent explorations. Among these targets, Target Area III exhibits favorable structural conditions, well-developed calcite veins, and pronounced superposition of multi-element geochemical anomalies, indicating considerable potential for further mineral exploration. Full article

Neighbourhood-scale improvements in building energy efficiency face intertwined challenges of retrofit adoption, distributional equity, and resilience to energy price shocks. While existing studies often examine individual policy instruments in isolation, how governance tools jointly shape diffusion dynamics, social sustainability, and fiscal feasibility remains insufficiently understood. This paper develops an agent-based model of a heterogeneous urban neighbourhood to examine how four governance instruments—incentives, feedback, participation, and compliance—interact to influence household retrofit adoption, emissions, energy burden outcomes, and public budget exposure. Outcomes are evaluated using an ESG-informed indicator structure: E captures aggregate neighbourhood emissions; S captures household energy burden (level, overburden prevalence, and inequality); and G captures governance feasibility (adoption/compliance dynamics and cumulative net public cost, defined as administration + subsidies + enforcement minus fine revenues). An exogenous energy price shock is introduced to assess social resilience using burden peaks, overshoots, recovery time, and post-shock volatility. The simulation results show that participation-based mechanisms generate rapid early diffusion and higher endpoint adoption, with correspondingly earlier and larger emission reductions; in the baseline runs, the incentive–participation mix (I+P) attains the highest endpoint adoption and the lowest endpoint emissions. Incentives and feedback yield more gradual diffusion and moderate improvements, while compliance reduces voluntary uptake but delivers partial emission reductions through enforcement and can generate net fiscal revenue under the accounting definition when fine revenues exceed enforcement outlays. Participation-centred mixes tend to lower the average burden trajectories and exhibit modestly smaller shock-induced peaks and overshoots, whereas inequality outcomes are more trade-off dependent: compliance-based enforcement can compress burden dispersion even with limited voluntary adoption, and adding compliance to participation primarily shifts performance toward lower inequality at higher net fiscal exposure. These findings suggest that neighbourhood-scale building energy governance depends on matching policy mixes to diffusion mechanisms, distributional objectives, and fiscal constraints. Full article

Land subsidence and structural instability at the Slănic Prahova salt mine have evolved significantly over 190 years of underground extraction, particularly following the mine’s expansion in 1970. This study reconstructs the complete geomechanical history from 1835 to 2025 and forecasts deformation trajectories up to 2050 using a calibrated creep-based numerical model. A high-fidelity geological model was developed in Leapfrog Works, with the numerical mesh generated in Rhinoceros and converted to FLAC^3D format via the Griddle plug-in. Salt creep was characterized using a Norton power-law constitutive model, with initial parameters derived from the steady-state phases of laboratory creep tests, and subsequently with calibrated parameters identified at the mine scale as n = 2.03 and A = 3 × 10⁻²⁵ s⁻¹ MPa⁻ⁿ. The simulation results demonstrate a high degree of correlation with field observations. These parameters were subsequently refined at the mine scale by integrating surface leveling data (1994–2025) and underground displacement records (2004–2019). The simulation results demonstrate a high degree of correlation with field observations, highlighting critical deformation zones. Maximum surface subsidence increased from approximately −560 mm in 1970 to −1020 mm by 1992, reflecting the intensified impact of later mining phases. The current maximum cumulative displacement is estimated at −1640 mm (2025) and is projected to reach −2060 mm by 2050. Underground, the largest displacement rates are concentrated in the eastern sector, driven by the synergistic effects of overburden loading and regional horizontal stress. Full article

Stress evolution during overburden stabilization in non-pillar mining with roof-cutting and roadway formation (NMRRF) in inclined coal seams is highly complex due to the combined influence of seam dip angle and mining method. This study investigates the spatial stress evolution and structural stability of the overburden through numerical simulation and theoretical analysis. Results indicate that along the strike direction, the peak abutment pressure ahead of the working face decreases from the lower to the upper sections. As mining advances, the peak in the lower section shifts significantly forward, whereas changes in the middle and upper sections remain minimal. After advancing 150 m, upward expansion of the pressure-relief zone ceases, with the relief height in the lower goaf being smaller than that in the upper region. Along the dip direction, a pressure-relief zone forms in the roof and floor after 30 m of advancement, while stress concentration zones develop in the coal on both sides. With continued mining, the highest point of the pressure-relief zone gradually deviates from the central axis toward the upper section and eventually stabilizes within deeper strata at a certain distance from the axis. By 150 m of advancement, the relief zone peaks in the upper-middle section of the working face, and the height of the caved zone in the upper goaf exceeds that in the middle and lower parts. An asymmetric “inverted J-shaped” stress shell forms along the working face centerline, evolving into an overall asymmetric stress shell with its apex located in the upper goaf. A mechanical model of the overburden structure is established, yielding an expression for the three-dimensional stress shell morphology. Based on the stability mechanism of overburden movement and the failure modes of key block structures, support strategies for the mining face are proposed. The findings provide theoretical insights for non-pillar mining under similar geological conditions. Full article

The lateral abutment stress and damage range of the coal seam are prerequisites for the layout of gob-side entries and surrounding rock control. They are influenced by the structure and mechanical properties of the coal seam and the overlying strata. To address this issue, this study establishes a mechanical analysis model for the lateral abutment stress and damage range under coupled conditions between the coal seam and overlying strata. This model systematically investigates the influence of various factors, including the fracture height and break angle of the overlying strata, the rotation angle and subsidence of key blocks, the burial depth and thickness of the coal seam, as well as the cohesion and internal friction angle of the coal mass. The study reveals that the weight and overburden load of the triangular hanging roof zone, along with the subsidence and rotation of the key blocks, are the key factors influencing the lateral abutment stress and damage range. Meanwhile, the reliability of the mechanical model has been substantiated through a combination of numerical simulation and in situ monitoring results. Full article

Background: Management of Mental Health Care Users is a critical component of the overall health care system, yet it is not given the serious attention it deserves due to stigma and discrimination against those living with mental health challenges. These results in mental health care users being readmitted to the hospital frequently, despite the poor resources and overburdened health care system. Aim: The aim of this study was to explore and describe the experiences of Psychiatric Nurses regarding the care of Mental Health Care Users in the selected hospitals in Limpopo Province, South Africa. Methods: A qualitative study was followed, where explorative, descriptive, and contextual designs were used. The researcher purposefully selected thirty-four Psychiatric Nurses who have been working in mental health units. Data was collected through unstructured interviews. Thematic analysis was utilized to analyze the data. Results: The study revealed significant challenges, such as poor mental health structures or no mental health unit at all, and this forces Psychiatric Nurses to mix critically ill medical patients with psychotic patients. Furthermore, there is a shortage of staff and treatment to manage users. Conclusions: In conclusion, the study showed that psychiatric nurses face serious emotional and resource-related challenges in caring for mental health care users. This highlights the urgent need for support from institutions, ongoing training, and better working conditions to improve the quality of mental health care. The success of the care, treatment, and rehabilitation of mental health care users depends on the support of MHCUs by family and management. Full article

Underground coal gasification (UCG) is an emerging energy technology that involves the in situ conversion of coal into syngas through controlled combustion within a subsurface excavation. The geomechanical processes associated with UCG can lead to significant overburden caving and surface subsidence, posing risks to surface infrastructure and groundwater systems. To accurately predict the size of overburden caving zones and associated surface subsidence, a prediction model was developed based on simulation results using discrete element method (DEM) numerical models. The main purpose of developing such a model is to establish a systematic and computationally efficient method for the rapid prediction of the height of overburden caving and its associated surface subsidence induced by underground excavation. The model is broadly applicable to different types of underground excavations, and UCG is used in this study as a representative application scenario to demonstrate the relevance and performance of the model. Sensitivity analysis indicates that excavation span, tensile strength, and burial depth are the primary controls on the height of the caving zone within the ranges of parameters investigated. Rock density is retained as a secondary background parameter to represent gravitational loading and its contribution to the in situ stress level. The derived model was validated using published numerical, experimental, and field measurement data, showing good agreement within practical ranges. To further demonstrate the application of the model developed, the predicted caving geometries were incorporated into finite element method (FEM) models to simulate surface subsidence under different geological conditions. The results highlight that the arch structure formed by overburden caving can help redistribute stresses and thereby reduce surface deformation. The proposed model provides a practical, parameter-driven tool to assist in underground excavation design, environmental risk evaluation, and ground stability management. Full article

As sustainable tourism gains global momentum, extended reality (XR) technologies have emerged as important tools for enhancing visitor experiences at overburdened World Heritage Sites while mitigating physical deterioration through non-consumptive engagement. However, existing research on immersive technologies in heritage tourism has largely relied on single-cultural samples and has paid limited attention to theoretically grounded boundary conditions in post-adoption behaviour. To address these gaps, this study extends the Expectation–Confirmation Model (ECM) by incorporating cultural distance (CD) and prior visitation experience (PVE) as moderating variables, and empirically tests the proposed framework using a mixed domestic–international sample exposed to an on-site XR application at the Badaling Great Wall World Heritage Site. Data were collected immediately after the XR experience and analysed using structural equation modelling. The results validate the core relationships of ECM while identifying significant moderating effects. Cultural distance attenuates the positive effects of confirmation on perceived usefulness as well as the effect of perceived usefulness on continuance intention, while prior visitation experience weakens the influences of enjoyment and visual appeal on satisfaction. These findings establish important boundary conditions for ECM in immersive heritage contexts. From a practical perspective, the study demonstrates that high-quality, culturally responsive XR can complement physical visitation and support sustainable conservation strategies at large-scale linear heritage sites. Full article

Overburden layers, composed of unconsolidated sediments, are widely distributed in construction, transportation, and water conservancy projects, but their inherent defects (e.g., developed pores, low strength) easily induce engineering disasters. Grouting is a core reinforcement technology, yet traditional design relying on empirical formulas and on-site trials suffers from high costs and low prediction accuracy. Numerical simulation has become a key bridge connecting grouting theory and practice. This study systematically reviews the numerical simulation of overburden grouting based on 82 core articles screened via the PRISMA framework. First, the theoretical system is clarified: core governing equations for seepage, stress, grout diffusion, and chemical fields, as well as their coupling mechanisms (e.g., HM coupling via effective stress principle), are sorted out, and the advantages/disadvantages of different equations are quantified. The material parameter characterization focuses on grout rheological models (Newtonian, power-law, Bingham) and overburden heterogeneity modeling. Second, numerical methods and engineering applications are analyzed: discrete (DEM) and continuous (FEM/FDM) methods, as well as their coupling modes, are compared; the simulation advantages (visualization of diffusion mechanisms, parameter controllability, low-cost risk prediction) are verified by typical cases. Third, current challenges and trends are identified: bottlenecks include the poor adaptability of models in heterogeneous strata, unbalanced accuracy–efficiency, insufficient rheological models for complex grouts, and theoretical limitations of multi-field coupling. Future directions involve AI-driven parameter optimization, cross-scale simulation, HPC-enhanced computing efficiency, and targeted models for environmentally friendly grouts. The study concludes that overburden grouting simulation has formed a complete “theory–parameter–method–application” system, evolving from a “theoretical tool” to the “core of engineering decision-making”. The core contradiction lies in the conflict between refinement requirements and technical limitations, and breakthroughs rely on the interdisciplinary integration of AI, multi-scale simulation, and HPC. This review provides a clear technical context for researchers and practical reference for engineering technicians. Full article

Soil permeability decreases with reduced saturation, making desaturation an effective strategy for seepage control. Air injection has emerged as a promising technique to induce desaturation in engineering applications that require rapid seepage prevention. Although this method has attracted considerable attention, its specific effects on soil saturation and permeability remain insufficiently understood. In this study, a modified conventional permeameter is used to examine the influence of air injection on the degree of saturation and permeability coefficient of sandy soil; simultaneously, the variation in air injection pressure during the gas injection process was monitored, and the influence of overburden pressure on the initial gas injection value was investigated. The findings reveal the following: (1) When other factors are the same, the increase in the air injection flow rate decreases the degree of saturation of sandy soil, and the air injection rate is 40 mL/min, which results in the degree of Fujian sand to achieve a maximum reduction to about 0.750; the increase in the relative density decreases the degree of saturation of sandy soil. (2) The decrease in the degree of sandy soil decreases the permeability coefficient of sandy soil; the desaturation effect of the air injection method varies for different sand samples, and the air injection method can reduce the permeability coefficient of Fujian sand by about 60% at most. (3) The change trend of air injection pressure is related to the gas migration process. Overburden pressure has a negligible influence on the initial value of air injection pressure; the initial pressure value of the air injection method is mainly related to hydrostatic pressure and is affected by the pore structure of the soil. Full article

Underground mining-induced surface subsidence poses significant risks to overlying structures, infrastructure, and the environment. Overburden delamination grouting has emerged as an effective technique to mitigate subsidence, but its design requires a comprehensive understanding of fractured-zone development, grouting-layer placement, isolation-layer stability, and grout material performance. This study developed an integrated methodology for overburden delamination grouting in longwall mining by combining fractured- and bending-zone analysis, grouting-layer design, isolation-layer stability evaluation, grout material strength design, and surface-subsidence monitoring for performance assessment. The mechanical properties of grout materials were systematically evaluated through laboratory testing, including compressive behavior and stress–strain response. Results indicate that ternary mixtures exhibit the best compressive stability, with a fly ash–coal gangue–slag powder ratio of 4:3:3 achieving a compressive ratio of 8.2%. The proposed workflow and selected materials were validated through three representative engineering case studies, demonstrating practical applicability under varied geological and mining conditions. Surface-subsidence monitoring results show that grouting effectively reduces subsidence and supports the continued safe performance of overlying structures. This study offers both theoretical guidance and practical solutions for sustainable subsidence control in underground mining. Full article

In the face of the urgent need for sustainable practices in the coal industry, we propose a novel green cut-and-fill mining method aimed at achieving material self-sufficiency and mitigating overburden subsidence. This method leverages the goaf roof as an in situ filling material, integrating long-wall caving mining efficiency with partial filling techniques. Through laboratory analog material modeling, numerical simulations, and structural mechanics modeling, we compare the performance of cut-and-fill mining and traditional caving mining methods. The results show that the cut-and-fill method offers more uniform and controlled deformation behavior. Specifically, vertical and horizontal displacements along 40 m survey lines are significantly reduced, with a maximum reduction on the order of millimeters, compared to caving mining. Furthermore, the floor stress concentration coefficient is lower, and the total number of fractures decreases, with shear fractures reduced by 8.8% and tensile fractures reduced by 66.9%. The gangue column in the cut-and-fill method effectively supports the goaf roof, preventing fracture formation and extending the deformation time. The results demonstrate the effectiveness of the cut-and-fill method for subsidence control, suggesting its potential for achieving green and sustainable coal mining practices. Full article

Underground mining often causes surface displacement and deformation above and around mined-out areas, and mining-induced subsidence has become a growing concern for ground stability worldwide. Given the proximity between the studied mine and a neighboring operation, potential mutual influences during extraction were examined to ensure the safety of surface structures. This study analyzes the stability of the overlying strata by combining theoretical prediction and numerical simulation, considering the cumulative effects of adjacent mining activities. The main findings are as follows: (1) The probability integration method was used to predict surface deformation and subsidence caused by underground mining, providing deformation data for the 4# shaft, 4# return air shaft, 5# return air shaft, and surrounding ground surface. (2) A three-dimensional geomechanical model was built using FLAC3D finite-difference software based on actual topographical and geological data to assess the impact of mining on overburden stability. Results show that the surrounding rock remained primarily in the elastic stage, with a maximum surface subsidence of 47.7 mm, confirming the structural stability of the 4# and 5# shafts. (3) Analyzing stress redistribution during deep ore extraction in both mining zones reveals that stress disturbances were mainly confined to the excavation areas, with a maximum local stress concentration of 83.34 MPa at stope corners. The combined mining activities resulted in an overall subsidence of approximately 48.7 mm, which decreased gradually outward from the center. This research presents an integrated theoretical and numerical framework that combines probability integration theory with FLAC3D simulation to assess the cumulative deformation and stress interactions of neighboring underground mines. The proposed method offers a practical and transferable tool for evaluating regional mine stability and surface deformation risks in multi-mine districts. Full article