Search Results (81)

To reveal the differences in stratum response among different environmental sections and the influences of key construction parameters on deep soil deformation during river-crossing double-line shield tunneling, the paper takes the East Genshan Road River-Crossing Tunnel as the engineering case, and systematically investigates the stratum responses of the onshore and riverbed sections as well as the effects of construction parameters via field monitoring, measured construction parameter data and three-dimensional finite element simulation based on ABAQUS. The simulation results suggest that, compared with the onshore section, the riverbed section may present larger cumulative displacement, more intense deep soil response and a wider influence range of transverse settlement under the investigated high-water-pressure and saturated soft-soil conditions. These differences are more reasonably interpreted as the combined effects of burial depth, stratum composition, mechanical properties, hydraulic boundary conditions, surface boundary constraints and overburden conditions. Among these factors, the high-water-pressure and saturated soft-soil environment may contribute to the enhanced disturbance diffusion and cumulative deformation response observed in the riverbed section. The longitudinal displacement evolution of the riverbed section presents obvious stratified transmission characteristics, and its transverse settlement trough shows a typical double-peak W-shaped distribution with larger peak values, wider trough profile and slower far-field attenuation. The single-factor parametric analysis suggests that, within the investigated parameter ranges, cutterhead torque produced the largest absolute settlement variation, followed by total shield thrust and tunneling speed. The results of this study can provide a reference basis for settlement control and construction parameter optimization of river-crossing double-line shield tunneling in high-water-pressure and saturated soft soil strata. Full article

Energy communities (ECs) are becoming a key institutional instrument for decentralizing the European energy transition, yet their implementation remains constrained by fragmented legal interpretation, uneven national transposition, and unresolved socio-technical coordination problems. This review synthesizes the peer-reviewed literature, EU primary legal texts, and national legislation to clarify the distinction between Renewable Energy Communities (RECs) and Citizen Energy Communities (CECs), alongside the amendment relationship between the RED II and RED III directives. The analysis demonstrates that the scalability of these initiatives depends less on theoretical legal recognition and more on aligning operational frameworks, including metering, settlement, cybersecurity, and equitable allocation rules. The Romanian case illustrates this challenge clearly: rapid prosumer growth creates valuable distributed generation but also exposes physical grid constraints, asymmetric socio-economic participation capacity, and weak experience with cooperative energy governance. To address these vulnerabilities, this paper contributes a focused analytical framework linking energy justice, peer-to-peer game-theoretic modeling, and the strategic integration of “anchor-prosumers.” The study argues that larger renewable self-consumers can act as stabilizing community anchors when internal energy prices are designed between wholesale export values and retail import prices, thereby improving both producer incentives and consumer affordability. Future research developments, including targeted surveys and longitudinal empirical validations, will sustain this claim and optimize the socio-economic resilience of decentralized energy markets. Full article

This study introduces a multi-source spatial methodology that moves beyond the traditional urban/rural dichotomy to classify the American landscape into detailed, temporally defined settlement types. By combining historical housing unit and population estimates (HHUUD10 and LTDB) standardized to 2010 census tract boundaries with high-resolution, grid-level data on the built environment (HISDAC-US), this research establishes a settlement typology based on the development history of detailed geographic units. This framework classifies areas (from Prewar Cores and 21st-Century Suburbs to exurban fringes, outlying towns and rural areas) based on their era of development and proximity to urban centers. Applying this typology reveals profound spatial and demographic decentralization spanning eighty years of metropolitan expansion. The findings demonstrate a stark geographic sorting: expanding greenfield edges and exurbs have become magnets for high-income, highly educated, and predominantly White populations. However, longitudinal tracking reveals a distinct morphological “life-course” within suburban rings. As older suburbs age and their housing stock depreciates, they open to wider demographic integration, transforming into destinations for Black and foreign-born residents. Furthermore, the data highlight a contemporary polarization of human capital, concentrated in both the newest suburban peripheries and the resurgent urban cores, contrasting with persistent economic decline in outlying towns and rural areas. Ultimately, this methodology provides a flexible, longitudinal framework for understanding the long-term morphological and demographic evolution of American settlement. Full article

Relying on the Dujiangyan Irrigation Project, the Siguniang Mountain Rail Transit project, and the Balang Mountain No.1 Large Longitudinal Slope Tunnel Project, this paper systematically studies the mechanical response of the surrounding rock and support structure induced by TBM tunneling in composite stratum by using the methods of indoor test, similar model test and numerical simulation. In model tests with different rock dip angles (0°, 10°, 20°, 30°), the main findings are as follows: (1) The maximum settlement of the arch crown reaches −4.89 mm (monitoring surface 2, 20° dip angle), the displacement of the arch waist is smaller than that of the arch crown, and the deformation of the soft rock section is more significant. (2) The peak radial surrounding rock pressure generally occurs at a distance of 5 cm from the tunnel wall, with the highest pressure in the soft rock area of the arch waist reaching 16.807 kPa (monitoring surface 4). (3) The lining stress increases with the increase in rock dip angle, and the stress distribution on the same monitoring surface shows as arch waist > arch crown > arch shoulder, with the maximum stress concentrated in the soft rock area of the arch waist. Then, the finite difference method is used for numerical simulation to analyze the convergence deformation mechanism in the composite formation. The results indicate a strong consistency between the simulated displacement/stress patterns of the surrounding rock and lining structure and the experimental data. The research results provide a theoretical basis and experimental reference for the design and construction of similar projects. Full article

Mechanical construction of metro-connected aisles is a novel construction method in the field of metro engineering, and it is being gradually applied to practical projects at present. However, current research predominantly focuses on the mechanical response of tunnel structures, with insufficient theoretical investigations into ground settlement. To study the ground settlement law caused by the mechanical construction of the metro-connected aisle, the ground settlement was divided into the superposition of settlement caused by the construction of the main shield tunnels and the connected aisle. The modified Peck formula was used to calculate the ground settlement caused by tunnel excavation. Based on the integration of the Mindlin solution, the ground settlement caused by the jacking force of the cutterhead was solved, and the three-dimensional calculation formula for ground settlement was derived. Taking the NO. 1 connected aisle of Shenzhen Metro Line 8 as the research object, the accuracy of the calculation formula was verified through comparative analysis with three-dimensional numerical simulation results and in situ monitoring data, and good agreement was observed. The research results indicate that after the construction of a connected aisle, a wedge-shaped surface appears on the settlement surface at the location of the connected aisle. The surface settlement curve presents a “U”—shaped distribution; as the depth increases, the stratum settlement curve presents a “W”—shaped distribution. The stratum disturbance caused by the connected aisle is more significant in its longitudinal direction than in the transverse direction. The theoretical calculation results show that the maximum surface settlement generated by the construction of the connected aisle is 0.61 mm, accounting for about 15.6% of the total settlement value (3.9 mm), and is far below the control value adopted by Shenzhen Metro. The calculation formula proposed in this article can be used to evaluate the surface settlement caused by the construction of connected aisles. Full article

Traditional villages in ecologically fragile and multi-ethnic frontier regions are increasingly threatened by rapid urbanization and socio-economic transformation. Northwestern Yunnan, located in the longitudinal valleys of the Hengduan Mountains, represents a key cultural landscape of plateau agropastoral civilization and ethnic interaction, yet its spatial organization and clustering mechanisms remain insufficiently understood. This study develops a four-dimensional analytical framework integrating four dimensions—spatial morphology (village distribution patterns and density), geomorphological conditions (elevation, slope, and terrain features), cultural attributes (ethnic composition and historical-cultural corridors), and architectural typologies (dominant residential structure types) to examine 246 officially recognized traditional villages. Using GIS-based spatial statistics, kernel density estimation (KDE), spatial autocorrelation, and a hierarchical overlay model, the study identifies the spatial structure (distribution patterns and density gradients), environmental adaptability (relationships with elevation, slope, and hydrological conditions), and multidimensional clustering characteristics (integrated clustering intensity across four analytical dimensions) of settlements. The results reveal a highly uneven and a statistically significant clustered spatial pattern ($R$ = 0.606, Moran’s $I$ = 0.251, p < 0.05) characterized by a “two corridors–six clusters–multiple nodes” structure. Settlement distribution demonstrates strong coupling with mid-elevation plateau basins, river valley systems, and trade-cultural corridors shaped by the Ancient Tea Horse Road. Multidimensional integration further classifies villages into three typologies—comprehensive, specialized, and general clusters—reflecting different levels of coordination among spatial, environmental, cultural, and architectural dimensions. These findings reveal the spatial regularities and multidimensional clustering characteristics of officially recognized traditional villages in Northwestern Yunnan, and suggest that environmental setting, historical corridors, and cultural-architectural features jointly shape the current recognized heritage landscape. The proposed framework provides a context-sensitive basis for differentiated heritage conservation and rural management in mountainous multi-ethnic regions. Full article

The deep foundation pit excavation of subway will cause horizontal displacement, uneven settlement and other adverse effects on the adjacent shield. The use of servo steel strut has a certain effect on deflection correction, but the current understanding of the influencing factors of deflection correction is not comprehensive. Based on structural and spatial symmetry, the influence of tunnel depth, tunnel and foundation pit clear distance and deformation control quantity of enclosure structure on deflection correction quantity was studied by symmetrically designed model test and numerical simulation, and the prediction formula of deflection correction quantity considering tunnel and foundation pit clear distance and deformation control quantity of enclosure structure was proposed. The results show that with an increase in the tunnel’s burial depth, deflection correction decreases significantly. When the tunnel is near the foundation pit bottom, there is no significant correction effect, and the control law of the tunnel ground pressure under the servo steel strut loading is consistent with the correction law. Deflection correction is negatively correlated with the tunnel and foundation pit clear distance, and positively correlated with the deformation control of the diaphragm wall. The curve of the deformation control of the enclosure structure and the deflection correction is parabolic. The deflection correction is an exponential function of the ratio of the deformation control of the enclosure structure to the clear distance between the tunnel and the foundation pit, and the servo deflection correction follows a normal distribution along the longitudinal axis of the tunnel, showing obvious symmetry characteristics in the foundation pit influence zone. Full article

Despite timber’s strategic role in the circular economy, its application in Türkiye remains negligible compared to the rigid reinforced concrete (RC) housing stock, which limits flexibility and penalizes the environment. This study investigates the adaptability and environmental performance of modular timber construction via a 17-year longitudinal case study in Seferihisar, İzmir. Using architectural observation, user interviews, 3D BIM, and a comparative LCA, findings reveal the structure successfully accommodated a six-phase functional transformation—the structure’s gross floor area increased by 6.19 times more (from 21 m² to 151 m²) and bed capacity from 2 to 18—with virtually zero demolition waste through dry-assembly techniques. Crucially, normalized LCA proves timber’s ecological superiority: achieving an embodied energy intensity of 6.60 GJ/m² (1.2 times less than the RC equivalent’s 7.97 GJ/m²). Furthermore, biogenic carbon storage enabled the timber dwelling to reach a negative Global Warming Potential (GWP) of −26,118.39 kgCO₂ (a carbon sink), whereas the RC model emitted +39,081.22 kgCO₂. Given that secondary housing predominantly comprises two-story structures, lightweight timber sustainably meets this typological demand. Ultimately, user-driven modular timber presents a resilient, eco-efficient, circular economy model for second-home and post-disaster settlements. Full article

Soil spatial variability is an inherent feature of natural strata, and random field theory provides an effective framework for quantifying it, aiding accurate deformation prediction. This study focuses on the tunnel section between Kepugongyuan and Gangduhuayuan Stations on Wuhan Metro Line 12. Its novelty focuses on analyzing dual-line shield-induced ground response with explicit consideration of multi-layer soil spatial variability. It examines the effects of the coefficient of variation and the horizontal/vertical spatial correlation distances of cohesion, internal friction angle, and elastic modulus—considering multilayer soil variability—on ground disturbance induced by twin-tunnel shield construction. The main findings include the following: (1) In cross-section, the settlement trough transitions from a “W”-shaped double trough to a “V”-shaped single trough as excavation advances, with the settlement center moving toward the midpoint between the tunnels. Longitudinally, soil heaves ahead of the shield and settles behind. (2) Ignoring spatial variability results in underestimated deformations; nearly 80% of stochastic simulations produced larger maximum surface settlements compared to deterministic analysis. (3) Ground loss and shield thrust disturbance are categorized into four zones based on tunnel diameter (D): Disturbance Zone, Secondary Zone, Transition Zone, and Undisturbed Zone. These findings provide practical guidance for predicting ground deformation and managing settlement-related risks in urban dual-line shield projects. Full article

Dense and complex underground structures impose stringent requirements on shield tunneling. In the close-proximity construction of super-large-diameter shield tunnels, challenges may arise, including adverse impacts on the normal operation of existing structures, as well as difficulties in ensuring the bearing capacity and deformation control of these structures during excavation. This study, based on the stratigraphic conditions of the Chengdu area, employs FLAC3D 7.0 version software to simulate the section where the Shuanghua Road Tunnel underpasses both Metro Line 10 and the Chengdu-Guiyang High-Speed Railway. The main conclusions are as follows: (1) Tunnel underpassing induces uneven settlement in the metro tunnel, with a maximum settlement reaching 47.7 mm. The settlement trough exhibits a twin-peak morphology during dual-line construction. When a single super-large-diameter tunnel line crosses the existing structural cluster, the maximum settlement is located directly above the crossing point. During dual-line crossing, the maximum settlement shifts towards the midpoint between the two new tunnel lines. (2) As the left line of the new tunnel approaches the existing structure, the cross-sectional deformation of the existing structure is “pulled” towards the direction of the excavated new tunnel. After the new left line moves away, the cross-sectional deformation gradually recovers to a bilaterally symmetrical state. (3) The tunnel cross-section undergoes dynamic “compression-tension” convergence changes during the construction process, with a maximum longitudinal tensile convergence of −1.28 mm. (4) During the underpassing of the existing structural cluster by the super-large-diameter tunnel, the maximum torsion angle is approximately −0.016°, occurring at the moment when the shield machine head first passes directly beneath, located directly above the new tunnel. The torsion angle of the existing structure is greatest during the first underpassing event, and the maximum torsion angle during the second underpassing is lower than that during the first. This study reveals the composite deformation mode of “settlement-convergence-torsion” during the underpassing of existing structural clusters by super-large-diameter shield tunnels, providing a theoretical basis for risk control in similar adjacent engineering projects. Full article

Seismic action significantly affects the mechanical properties and failure characteristics of bridge pile foundations, soft rocks, and sediments. This study, by integrating shaking table tests, numerical simulations, and on-site monitoring, systematically analyzed the influence mechanisms of seismic intensity, sediment characteristics, and pile foundation layout on structural responses. Tests show that the 2.5-layer rock–sand pile exhibits nonlinear bearing degradation under seismic force: when the seismic acceleration increases from 0 to 100 m/s², the bearing capacity of the pile foundation decreases by 55.3%, and the settlement increases from 3.2 mm to 18.5 mm. When the acceleration is ≥2 m/s², the cohesion of the sand layer is destroyed, causing a semi-liquefied state. When it is ≥10 m/s², the resistance loss reaches 80%. The increase in pore water pressure leads to dynamic settlement. When the seismic acceleration is greater than 50 m/s², the shear modulus of the sand layer drops below 15% of its original value. The thickness of the sediment has a nearly linear relationship with the reduction rate of the bearing capacity. When the thickness increases from 0 to 1.4 cm, the reduction rate rises from 0% to 55.3%. When the thickness exceeds 0.8 cm, it enters the “danger zone”, and the bearing capacity decreases nonlinearly with the increase in thickness. The particle size is positively correlated with the reduction rate. The liquefaction risk of fine particles (<0.1 mm) is significantly higher than that of coarse particles (>0.2 mm). The load analysis of the pile cap shows that when the sediment depth is 140 cm, the final bearing capacity is 156,187.2 kN (reduction coefficient 0.898), and the maximum settlement is concentrated at the top point of the pile cap. Under the longitudinal seismic load of the pile group, the settlement growth rate of the piles containing sediment reached 67.16%, triggering the dual effect of “sediment–earthquake”. The lateral load leads to a combined effect of “torsional inclination”, and the stress at the top of the non-sediment pile reaches 6.41MPa. The seismic intensity (PGA) is positively correlated with the safety factor (FS) (FS increases from 1.209 to 37.654 when 10 m/s²→100 m/s²), while sediment thickness (h) is negatively correlated with FS (FS decreases from 2.510 to 1.209 when 0.05 m→0.20 m). The research results reveal the coupled control mechanism of sediment characteristics, seismic parameters, and pile foundation layout on seismic performance, providing key parameters and an optimization basis for bridge design in high-intensity areas. Full article

Current research on heritage corridors predominantly focuses on linear heritage in Europe and America, while studies in Asia urgently need to be expanded. This study investigates China’s linear heritage. Based on the minimum cumulative resistance (MCR) model, it conducts heritage corridor construction for the Henan section of the Sui–Tang Grand Canal, and reveals the following: (1) A total of 252 heritage sites were classified into three categories: canal hydraulic heritage (13.5%), canal settlement heritage (21.4%) and related heritage (65.1%), exhibiting a “local clustering under global dispersion” pattern with a core–secondary–edge structure. (2) The influence of natural–social resistance factors was ranked as follows: elevation > roads > land use > slope. Interwoven corridors were simulated by GIS and optimized to four primary corridors with multiple secondary corridors. (3) The transverse zone of the primary corridors was stratified into core area (0–10 km from the centerline), buffer area (10–25 km), and influence area (>25 km) with a total width of 25–30 km. The longitudinal section was partitioned into four subsections based on hydrological continuity and heritage density. Then, a tripartite conservation framework characterized by “heritage clusters–holistic corridor–transverse stratification and longitudinal section” was proposed. It aimed to provide insights into methodologies and content structuring for transnational linear heritage (e.g., the Silk Road and the Inca Trail). Full article

Background/Objectives: Climate change is intensifying vector-borne disease (VBD) transmission globally, causing over 700,000 annual deaths, yet systematic evidence comparing climate–health pathways across urban and rural settlements remains fragmented. This scoping review aimed to synthesize evidence on the differential impacts of extreme weather events on vector-borne disease transmission between urban and rural environments and identify settlement-specific prevention and healthcare preparedness strategies. Methods: A scoping review following PRISMA-ScR guidelines searched PubMed, EMBASE, Web of Science, and Scopus databases for studies examining climate–vector-borne disease relationships across settlement types. Sixteen empirical studies were analyzed using narrative synthesis, with urban–rural comparisons largely inferential given limited direct comparative studies. Results: From 6493 records identified, 4875 were screened after duplicate removal, yielding 16 studies for analysis. Studies covered multiple vector-borne diseases, including malaria, dengue, leishmaniasis, chikungunya, and Zika, across diverse geographic regions. Urban environments demonstrated infrastructure-mediated transmission dynamics characterized by heat island amplification exceeding vector survival thresholds, drainage system vulnerabilities creating breeding habitats, and density-driven epidemic spread affecting healthcare surge capacity. Rural settings exhibited ecosystem-mediated pathways involving diverse vector communities, agricultural breeding sites, and seasonal spillover from wildlife reservoirs, with healthcare accessibility challenges during extreme weather events. Critical research gaps included a limited number of longitudinal comparative studies and geographic variations in evidence generation. Conclusions: Extreme weather events create fundamentally distinct vector-borne disease transmission pathways across urban–rural gradients, necessitating settlement-specific prevention strategies and healthcare preparedness approaches. Evidence-based recommendations include urban infrastructure improvements, rural early warning systems, and cross-sectoral coordination frameworks to enhance the adaptive capacity for climate-resilient vector-borne disease prevention. Full article

To investigate the longitudinal mechanical behavior of shield tunnels traversing soft and hard heterogeneous strata, a refined three-dimensional numerical model was developed using ABAQUS. The model includes tunnel segments, longitudinal bolts, reinforcement, longitudinal thrust, and additional loading conditions to simulate realistic mechanical responses during construction and operation. The results show that significant differential settlement occurs at the interface between soft and hard soils. Greater joint dislocation is observed on the soft soil side, while joint opening is more pronounced on the hard soil side. Compressive damage concentrates at the soil interface, whereas tensile damage is more severe in soft soil zones. The dislocation at the vault is distributed over a wider area but has a smaller magnitude than that at the arch bottom. Parametric analysis indicates that increasing longitudinal thrust enhances tunnel stiffness and reduces joint dislocation. However, it also leads to increased compressive and tensile damage due to greater trans-verse deformation. Optimizing bolt configuration, including diameter, inclination, and quantity, improves longitudinal stiffness and joint integrity, helping to reduce tensile damage and control deformation. These findings provide theoretical support for the structural design and performance optimization of shield tunnels in complex geological environments. Full article

In response to issues of long construction cycles, high pollution, and labor shortages in traditional cast in situ subway station construction, a refined 3D model of a large-segment prefabricated subway station was established using ABAQUS software 2024, with mechanical behavior throughout the construction process studied based on the Shenzhen Huaxia Station project case. The model incorporates a concrete inelastic damage constitutive model and a steel elastic–plastic model, accurately simulates key components, including dry joints of mortise–tenon grooves, prestressed reinforcement, and bolted connections, and implements a seven-phase construction sequence. Research findings indicate the following: (1) During component assembly, the roof vault settlement remains ≤3.8 mm, but backfilling significantly increases displacements (roof settlement reaches 45 mm, middle slab deflection measures 66.91 mm). (2) Longitudinal mortise–tenon joints develop stress concentrations due to stiffness disparities, with mid-column installation slots identified as vulnerable zones exhibiting maximum Von Mises stress of 32 MPa. (3) Mid-column eccentricity induces structural asymmetry, causing increased deflection in longer-span middle slabs, corbel contact stress differentials up to 6 MPa, and bolt tensile stresses exceeding 1.1 GPa. (4) The arched roof effectively transfers loads via three-hinged arch mechanisms, though spandrel horizontal displacement triggers 5 cm rebound in diaphragm wall displacement. Conclusions confirm overall the stability of the prefabricated structure while recommending the optimization of member stiffness matching, avoidance of asymmetric designs, and localized reinforcement for mortise–tenon edges and mid-column joints. Results provide valuable references for analogous projects. Full article