Search Results (741)

The conventional double-sidewall pilot tunnelling method (CDWM) has been widely applied in the construction of large-span tunnels. However, when applied to shallow-buried tunnels in weak surrounding rock, the method often suffers from excessive deformation and complex support conversion. To address these limitations, this study proposes an optimized excavation scheme, namely the double-sidewall pilot tunnelling method with reserved rock walls (DRWM). The Yangjiashan Tunnel in Zhejiang Province, China, was selected as the engineering case for investigation. Field monitoring data and numerical simulations were integrated to evaluate the deformation behaviour and structural response of the tunnel during excavation. The results indicate that DRWM significantly improves deformation control compared with the conventional CDWM. The maximum crown settlement and horizontal convergence were effectively reduced, and stress concentration in the initial support structure was mitigated. Furthermore, a sensitivity analysis was conducted to investigate the influence of the lateral distance between the temporary support and the reserved rock wall. Within the investigated single-parameter analysis, a spacing of 0.4–0.5 m showed a relatively balanced response in terms of crown settlement, horizontal convergence, support stress, and construction operability. The findings demonstrate that, under the investigated Grade V weak rock conditions, the DRWM showed improved deformation control compared with the CDWM in the numerical comparison, highlighting its potential applicability for optimization in comparable engineering settings. Full article

Railway cable-stayed bridge construction is characterized by high complexity and substantial safety risk. Deficiencies in safety control may result in serious accidents (e.g., collapse and falls), causing significant casualties and economic losses; therefore, clarifying risk interactions and accident-causing mechanisms is essential. This study proposes a fuzzy DEMATEL–ISM approach in which fuzzy sets capture uncertainty in experts’ linguistic assessments. DEMATEL quantifies influence strengths and causal relationships among factors, and ISM constructs a multi-level hierarchy to explain accident causation. Twenty safety influencing factors are identified and grouped into five categories: management, human, material and equipment, construction technology, and environmental conditions. The obtained accident-causing mechanism comprises seven hierarchical levels: L₁: collapse and fall accidents, L₂: direct factors, L₃–L₅: indirect factors, and L₆–L₇: root factors. This mechanism is a chain of events that leads to an accident, with the nodes improper prestressing, structural deformation and differential settlement. These key nodes can be avoided by reinforcing safety management system implementation, daily supervision and inspection, and education and training on the subject of safety to ensure the safety of railway cable-stayed bridge construction. Full article

Understanding the movement behavior of upper blocks along rock joints or weak planes is crucial for the geological hazard forecast and prediction. This paper presents experimental and numerical investigations of a saw-tooth joint under shear and normal load conditions. Multi-stage direct shear tests under different normal load conditions were conducted using a direct shear box apparatus. The reverse dilation behavior of the upper specimen was observed by measuring the normal displacement at the four corners of the upper block. Laboratory test results show that, under lower normal loads, the normal displacement of the upper specimen on the applied shear force side initially decreases (settlement), while the settlement reverses to heave (dilation) when the shear displacement reaches a certain value. However, the settlement reverse behavior does not occur under large normal loads. Corresponding numerical simulation confirms that this settlement reversal is controlled by the specimen fracturing. The saw-tooth asperities are sheared off under a large normal load, while the upper specimen climbs along the slope of the bottom specimen under lower normal loads. Consequently, the changes in contact area, interface normal stress, interface shear stress, and normal displacement of the joint differ significantly between large and low normal load conditions. This research deepens our understanding of the shear-induced dilation and fracture behavior of saw-tooth joints, and the results can provide guidelines for evaluating the stability of geological rock mass. Full article

Ceramic production technology is a key indicator of craft specialization and social differentiation in Late Neolithic societies of the Central Plains. This study investigates Longshan-period pottery excavated from three representative sites, Niumugang, Zhoulonggang, and Shigudui in western Shangqiu, Henan Province. A suite of archaeometric techniques, including X-ray fluorescence (XRF), infrared spectroscopy (IR), X-ray diffraction (XRD), differential thermal analysis (DTA), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS), was employed to systematically examine the chemical composition, mineralogical phases, thermal behavior, and microstructural characteristics of the pottery assemblages. The results reveal statistically significant differences (p < 0.05) in the contents of major ceramic-forming oxides (SiO₂, Al₂O₃, Fe₂O₃, CaO, etc.) among the three sites. Pottery from the Shigudui site exhibits the narrowest range of compositional variation, whereas that from the Zhoulonggang site shows moderate dispersion. In contrast, pottery from the Niumugang site displays the widest compositional range. Mineralogical analyses indicate that pottery from all three sites is primarily composed of quartz, mica, and mullite. Notably, the high degree of mineralogical homogeneity observed in the Shigudui assemblage reflects a well-controlled and technologically mature firing process. Microstructural observations further demonstrate that pottery from the Shigudui site is characterized by uniformly dense fabrics, functionally differentiated vessels from the Zhoulonggang site exhibit clear technological stratification, and black pottery from the Niumugang site shows highly compact microstructures. These technological patterns closely correspond to differences in vessel assemblages and indicate varying levels of craft specialization and production control. Together, the results provide archaeometric evidence for the differentiation of settlement hierarchy and the development of specialized handicraft production during the Longshan period, contributing to a deeper understanding of regional technological interaction and social processes within the Longshan cultural sphere of the Central Plains. Full article

This study investigates how different rural landscape types shape visual attention and physiological responses, with the aim of informing more targeted rural landscape renewal. Four typical rural landscape types in the suburbs of Hefei, China, were examined: Flat Farmland (FF), Hilly Forest (HF), Developed Plain (DP), and Water-network Lowland (WNL). All four study villages are project villages in the suburban area of Hefei where rural revitalization is currently being advanced. This study therefore treats them as empirical cases within the context of rural revitalization in China, using them to examine perceptual differences among rural landscape types and their implications for rural landscape renewal. A two-stage research design was adopted to balance field realism and laboratory control. In the first stage, 40 representative scene images were selected by combining field video records with fluctuations in on-site skin conductance response (SCR). In the second stage, laboratory experiments were conducted while participants viewed the selected images, during which eye-tracking, skin conductance, and heart rate data were recorded simultaneously. These measures were used to characterize visual attention allocation and autonomic physiological responses across different rural landscape types, rather than to directly measure landscape preference. For Area of Interest (AOI) analysis, each image was coded into six landscape element categories: vegetation, buildings, roads, sky, vernacular buildings, and water bodies. The results revealed significant typological differences in overall visual search patterns and autonomic responses. Gaze hotspots were concentrated on identifiable targets and boundary regions in the foreground and midground, whereas the sky attracted relatively limited attention. FF primarily emphasized vernacular buildings and farmland boundaries, HF emphasized settlement interfaces and spatial transition nodes, DP emphasized road junctions and facilities along routes, and WNL emphasized water bodies and water–land interface zones. These findings suggest that a two-stage multimodal design can provide supporting evidence for understanding type-specific perceptual responses and can support more targeted strategies for rural landscape renewal. Full article

The vertical jacking method is a trenchless construction technique in which standpipes are jacked upward from a horizontal main pipeline through overlying soil, and it is widely applied in marine outfall projects. Taking a deep-sea tailwater outfall in Ningbo as the case study, this research develops a three-dimensional finite element model using ANSYS 2021 R1 based on actual geological and construction conditions. The settlement and stress responses of the horizontal main pipeline during jacking are analyzed and validated against field monitoring data. The numerical results agree well with the field measurements, with an average error of 7.29% for settlement and less than 9.83% for circumferential stress. The main pipeline exhibits a settlement pattern characterized by larger deformation in the middle and smaller at both ends, with a maximum value of 0.90 mm, decreasing with distance from the opening ring. Circumferential stress initially increases and then stabilizes, with maximum tensile and compressive stresses of 0.082 MPa and 0.056 MPa, respectively. Overall stress levels remain well below structural strength, indicating that structural damage is unlikely under the investigated conditions. These findings provide a case-based reference for structural design, construction control, and monitoring layout in marine outfall projects with similar geological and construction conditions. Full article

Tourism safety in high altitude destinations is strongly affected by the combined effects of environmental constraints, tourism exposure, and safety support capacity. The Qinghai–Tibet Plateau (QTP), characterized by high altitude, complex terrain, sparse settlements, and limited emergency accessibility in remote areas, provides a representative case for tourism risk assessment in extreme plateau environments. To predict and interpret the spatial pattern of tourism risk on the QTP, this study constructs an assessment framework based on “Hazard–formative factors + Risk exposure + Safety security” and integrates XGBoost with SHAP interpretable machine learning. Eleven indicators representing environmental conditions, tourism exposure, and safety support capacity were used to model tourism risk at a 1 km × 1 km spatial resolution. The optimized XGBoost model achieved an AUC of 0.877, indicating good predictive performance. The results show that tourism risk on the QTP presents a spatial pattern of “high in the northwest and low in the southeast”. High risk and relatively high risk areas account for approximately 74.98% of the study area and are mainly distributed in remote hinterlands and northwestern plateau regions, whereas low risk areas are concentrated around southeastern river valleys, towns, mature scenic areas, and major transport corridors. SHAP analysis indicates that Distance to towns is the most important factor influencing predicted tourism risk, followed by Reception facility kernel density, Relief degree of land surface, and Scenic spot kernel density. Nonlinear and interaction analyses further suggest that remoteness, tourism facilities, terrain relief, and scenic area concentration jointly shape the predicted risk pattern. The findings provide spatial evidence for differentiated tourism risk management, including regular tourism development in relatively safe urban and scenic nodes, controlled management of medium risk tourism corridors, and stricter access management in remote high risk areas. Full article

Permafrost foundations are prone to settlement during thawing, resulting from both thaw settlement and thaw-induced compression. The relative contributions of these components are strongly influenced by soil structure and loading conditions. Therefore, clarifying their interaction and identifying the conditions for significant compressive deformation are essential for accurate predictions. Laboratory tests were conducted to determine the thaw-settlement and thaw-compression coefficients. A new index, the thaw proportion of thaw settlement, was introduced to quantify the relative contributions of the two deformation components. By combining this ratio with compressive strain characteristics, criteria for identifying significant thaw-compression deformation and the corresponding load–porosity conditions were established. In addition, multiple machine learning models were developed, and their predictive performance was systematically evaluated. The main findings are outlined as follows: (1) The thaw proportion of thaw settlement is controlled by soil type, natural water content, dry density, and external load, with clear differences among soil types. It increases with water content, but decreases with increasing dry density and load. (2) Significant thaw-compression deformation is defined by a compressive strain of 8%, and the corresponding load–porosity conditions are identified. (3) Machine learning models effectively predict permafrost deformation. After Bayesian Optimisation (BO), performance improves markedly, with the BO-Support Vector Machine (SVM) model achieving the highest accuracy for thaw-settlement-coefficient prediction (R² = 0.85), and the BO-Extreme Gradient Boosting (XGBoost) model performing best for post-thaw compressive strain (R² = 0.95). Full article

Land-use planning in ecologically sensitive landscapes requires balancing biodiversity conservation, ecosystem service provision, agricultural production, settlement expansion, and infrastructure demand within a single spatial system. This challenge is particularly significant in Mediterranean environments, where long-term land transformations and increasing development pressures intensify conflicts among competing land-use priorities. Accordingly, the present study develops an integrated spatial zoning and decision-support framework for Osmaniye Province, southern Türkiye. The framework integrates fuzzy multi-criteria evaluation, CatBoost-based machine learning, SHAP-based interpretability, and NSGA-II multi-objective optimization. The workflow followed a sequential decision process in which an expert-derived zoning surface was first established through fuzzy evaluation, reconstructed from continuous spatial predictors using CatBoost, interpreted through SHAP, and refined through NSGA-II under explicit spatial constraints. By using the expert-derived zoning surface as the learning target, the CatBoost stage aimed to evaluate the internal consistency and spatial learnability of the planning logic within a present-day zoning context. The results indicated that the integrated framework distinguished conservation, controlled-use, and development priorities while identifying the key environmental and anthropogenic drivers shaping class-specific zoning outcomes. The final zoning structure allocated 37.9% of the study area to conservation, 43.6% to controlled use, and 18.5% to development. The study shows that by including a transitional zone with varying proportions of conservation, controlled use, and development, a more balanced distribution among the three goals can be achieved compared to a fixed partition into these three zones. The findings further demonstrate that this approach is more effective than current zoning, which does not accommodate such trade-offs. 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

Given the challenges posed by high groundwater levels, thick sand layers, and strong permeability in water-rich sandy strata, cut-off walls often fail to fully isolate the hydraulic connection between the inside and outside of a foundation pit. As a result, dewatering inside the pit—especially from confined aquifers—can cause significant external groundwater drawdown and subsequent ground settlement. Using a deep excavation conducted in Xiamen as a case study, this study developed a two-dimensional hydro-mechanical coupled finite element model to systematically investigate the effects of various dewatering scenarios and soil permeability coefficients on surface settlement around the pit, and to reveal settlement patterns induced by dewatering and excavation in such strata. Field monitoring data were incorporated to validate the numerical model, ensuring accuracy and reliability. Key findings include the following: (1) Dewatering contributes to over 76% of the total settlement at each stage, with confined drawdown being the dominant factor, implying that dewatering optimization should take priority over controlling excavation rate. (2) Under confined dewatering, the settlement influence zone extends beyond 80 m, far exceeding the extension caused by excavation alone; thus, monitoring and protection ranges must be adjusted dynamically. (3) The horizontal permeability of sand shows a nonlinear positive correlation with settlement, and this sensitivity grows with depth, highlighting the need for accurate permeability determination and stricter controls in deep excavations within water-rich sand layers. From an engineering perspective, these findings underscore the importance of prioritizing confined aquifer dewatering management, dynamically expanding settlement monitoring zones, and rigorously characterizing permeability profiles to mitigate excessive ground settlement and protect adjacent infrastructure. Full article

This paper examines the resilience of deforestation control policies across land tenure regimes in the Brazilian Legal Amazon, using Brazil’s post-2019 shift in environmental governance policies as a quasi-natural experiment. Combining high-resolution deforestation data with detailed tenure classifications, the analysis evaluates how land governance mediates deforestation outcomes under weakened enforcement and regulatory rollback. Using a difference-in-differences framework with spatial panel data and event-study specifications, the results reveal substantial heterogeneity across tenure regimes. Areas characterized by strong legal recognition—particularly homologated Indigenous territories and strictly protected conservation units—remain comparatively resilient, exhibiting stable or declining deforestation. In contrast, lands with weaker or incomplete property rights, including non-homologated Indigenous territories, agrarian settlements, and untitled public lands, experience significant increases in deforestation. The findings also highlight important within-land category variation, underscoring the role of formal recognition and cadastral validation in shaping environmental outcomes. Overall, the results demonstrate that the durability of deforestation reductions depends critically on the strength of land tenure institutions in the face of changing policy regimes. Full article

To improve construction efficiency for large-section tunnels in sandstone–mudstone strata, this study investigates the applicability of the two-bench method and the three-bench method for grade IV and grade V surrounding rock, respectively. Based on FLAC3D, numerical simulations of excavation and support for the two benching methods were conducted to analyze deformation responses, including ground settlement, crown settlement, haunch convergence, floor uplift, and face extrusion. The simulation results were then compared and validated against field monitoring data to evaluate the applicability and feasibility of the construction methods. The results show that, for grade IV surrounding rock excavated using the two-bench method, crown settlement, floor uplift, and horizontal convergence converge and stabilize on days 17, 15, and 25, with stable values of 14.0 mm, 10.3 mm, and 13.2 mm, respectively. For grade V surrounding rock excavated using the three-bench method, these indices stabilize on days 24, 22, and 32, with stable values of 26.3 mm, 20.3 mm, and 20.8 mm, respectively. The surrounding rock pressures at the crown and spandrel gradually attenuate after excavation and stabilize at 1–4 MPa after approximately 20–26 days, whereas stress release at the haunch lasts longer and the stabilized stress level remains higher. Meanwhile, the anchor bolt axial force at the haunch is significantly greater than that at the spandrel, indicating that the haunch is a critical zone for support load-bearing and deformation control. The benching method can effectively control surrounding rock deformation under grade IV and V surrounding rock conditions in sandstone–mudstone strata; however, in engineering practice, the haunch should be treated as a key monitoring target, and targeted support and reinforcement measures should be implemented. Full article

Urban design that improves microclimate can significantly enhance the ecological livability of human settlements, while the climate-adaptive wisdom of applying local water-net landscapes to modern urban renewal requires further validation. To investigate the optimization mechanism of waterscape on microclimate comfort, this study focuses on the public space of Xinsheng District in the Suzhou water-net region. By integrating continuous incremental multi-scenario form design, computational fluid dynamics (CFD) multi-physics simulation, and climate sensation evaluation, we reproduce the spatial differentiation of microclimate and comfort gradients across multi-hour periods during hot summer daytime within the built-up environment involving waterbodies, vegetation, and buildings. Consequently, an indicator of comfort improvement efficiency (CIE) is proposed to measure the spatial effectiveness of per-unit-area water surface expansion on climate sensation. Results show that when controlling other morphological parameters and designing three incremental waterbody scenarios—no water surface, 50% water, and 100% waterscape—the relative comfort area expanded across all time periods as water increased. This implies that waterscape variations exert a positive effect on microclimate suitability. However, during the expansion of water area at each time, the CIE was higher in the 0–50% initial stage of water surface increase compared to the 50–100% later morphological stage. Therefore, this study reveals the stepwise nonlinear trend by which increased water area in the built-up environment improves the climate suitability of waterfront spaces. Furthermore, under constraints of equivalent area and other geometric forms, a more dispersed and networked waterscape was found to be a superior spatial strategy. This confirms the microclimate wisdom of the water-net landscape in the Jiangnan locality, providing form optimization guidance for ecologically oriented urban renewal design. Full article

With decarbonization, decentralization, and digitalization, energy coordination increasingly involves many actors, heterogeneous cyber–physical data, and compliance-sensitive settlement workflows. Although blockchain has been widely discussed in this domain, existing studies are still fragmented across application-specific or platform-specific narratives. As a result, it remains difficult to compare recurring mechanisms across scenarios or to determine which blockchain functions are operationally justified in deployable energy systems. We address that fragmentation through a structured narrative review of 41 representative sources, including prior surveys, foundational technical references, and scenario-specific studies. We formulate three research questions concerning architectural positioning, cross-scenario mechanisms, and deployment barriers. On this basis, we synthesize a unified five-layer reference architecture that links off-chain physical infrastructure and trusted data acquisition to protocol-level trust anchoring, reusable business services, interface and compliance functions, and application scenarios. The framework is then used to compare five recurring scenario families, namely peer-to-peer energy trading, carbon markets and renewable energy certificates, electric vehicle charging and vehicle-to-grid services, virtual power plants, and grid flexibility coordination. The analysis shows that blockchain is most defensibly positioned as an evidence-and-settlement trust layer, rather than as a replacement for real-time physical control. It also identifies three persistent adoption bottlenecks, namely scalable ledger interaction, trustworthy cyber–physical data binding, and interoperability with regulatory and operational infrastructures. By making the trust boundary explicit and by providing a common analytical lens for cross-scenario comparison, this review clarifies the scientific contribution of blockchain to energy systems and outlines stakeholder-oriented directions for deployable hybrid designs. Full article