Historische Eisenbahnviadukte sind stadt‐ bzw. landschaftsprägende Bauwerke. Aufgrund ihres Charakters als bedeutende Bestandteile der gebauten Umwelt, aber auch als wichtige wirtschaftliche Werte, ...ist der respektvolle Umgang bei Entscheidungen zur Instandsetzung und Weiternutzung dieser Zeugnisse zurückliegender Ingenieurbaukunst unabdingbar. Oft gehen derartige Umbaumaßnahmen mit einer umfassenden Erweiterung der Funktion des Bauwerks einher. Neben einer einfachen Verbreiterung des Fahrwegs können auch zusätzliche technische Einrichtungen, zum Beispiel Oberleitungsanlagen, zu erheblichen Eingriffen in das Erscheinungsbild des Bauwerks führen. Bauen im historischen Bestand stellt sowohl an die Planung als auch an die Bauausführung besondere Anforderungen.
Heiligenborn viaduct
Historic railway viaducts define the cityscape or landscape. The fact that they actively shape and characterise the built environment and are considered important economic assets must, therefore, be taken into account for the restoration and further use of these testimonies of historic civil engineering. Such restoration measures are often accompanied by extensive enhancements of the structure's function. Apart from a simple widening of the track, additional technical installations such as overhead line equipment can have a significant impact on the viaduct's appearance. Thus, the restoration of heritage buildings and structures encompasses specific requirements for construction planning and construction work.
Resource-based cities often face land scarcity during their developmental and expansionary phases. However, repurposing the goaf sites of suburban coal mines has been recognized as an effective ...strategy for alleviating this issue, particularly pertinent for suburban coal mines using strip mining techniques to protect ground-level structures. Old strip mining goaf is easily influenced by disturbance and leads to secondary surface deformation, which will threaten the construction above old strip mining goaf. Therefore, it is essential to provide a basis and reference for decision-makers regarding surface residual subsidence for strip mining. In the paper, based on the morphology and structure of the old strip mining goaf before the surface residual subsidence, the reason and mechanism of the residual subsidence of old strip mining goaf are studied. The results show that the main reasons for the “activation” of old strip mining goaf are the re-compaction of the under-compacted part of the fractured rock mass in the caving zone, the stripping and yielding of coal pillar under the action of groundwater erosion, weathering, and the collapse of residual voids. Based on the above analysis, a prediction model of the surface residual subsidence of the old strip mining goaf is proposed, which takes into account the compaction of the under-compacted area, the collapse of the residual voids, and the stripping and yielding of the coal pillar. The proposed method is implemented to evaluate the stability of a city viaduct goaf. Our research outcomes bear valuable theoretical and practical implications for site stability assessments of old strip mining goafs and the sustainable repurposing of land resources in suburban resource-based cities.
Viaduct is a ubiquitous transportation infrastructure in the congested megacities worldwide to improve the accessibility and capacity of urban transportation network. However, there is a lack of ...understanding of the impacts of the interplay between viaduct-ground emissions and viaduct-canyon configurations on the particle distribution in urban street canyon. To fill the research gap, we conducted vertical measurements of particle number concentrations (PNCs) at different heights of “street canyon along a viaduct” to reveal effect of viaduct on the vertical distribution of PNCs in street canyon. Observation results indicated that the vertical profiles of PNCs exhibited bimodal distribution patterns, which were more significant for coarse particles than fine particles. The one peak appeared at ground level and the other at the viaduct height, indicating the impacts of “double” emission sources (i.e., the emissions on the ground and viaduct) and the hindrance of viaduct to particle diffusion. We further modelled the role of viaduct in street canyon through Computational Fluid Dynamics (CFD) simulations to reveal the vertical distribution of particles under different viaduct-canyon configurations and discern the contributions of viaduct and ground emissions to the particle distribution. Simulation results showed that viaduct changed airflow field and turbulence structure and elevated particle concentrations in street canyon while the optimized viaduct-canyon configurations including higher viaduct height (12 > 10 > 8 m), smaller aspect ratio (0.5 > 0.67 > 1), and shorter centerline distance (0 > 1 > 2 m) between canyon and viaduct could bring better dispersion conditions and lower particle concentrations. Additionally, ground emissions contributed more to the vertical distribution of particles on the leeward side of street canyon than viaduct emissions while the windward side displayed the opposite characteristics to the leeward side. These findings revealed the general patterns of particle diffusion in viaduct-canyon configurations and provided implications into viaduct design and traffic management to alleviate local particulate pollution.
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•Spatial distributions of particles in “street canyon along a viaduct” are studied.•Field study and simulation are used for impacts of viaduct on particle distribution.•Measured profiles and slopes of wind speed & particles are used to calibrate model.•Viaduct alters airflow, adds emission sources, and changes particle distribution.•Ground and viaduct emission separately affect particles on leeward/windward sides.
Environmental concerns have been raised on the adverse health effects of vehicle emissions in micro-scale traffic-crowded street canyons, especially for pedestrians and residents living in near-road ...buildings. Viaduct design is sometimes used to improve transportation efficiency but possibly affects urban airflow and the resultant exposure risk, which have been rarely investigated so far. The personal intake fraction (P_IF) is defined as the average fraction of total emissions that is inhaled by each person of a population (1 ppm = 1 × 10−6), and the daily carbon monoxide (CO) pollutant exposure (Et) is estimated by multiplying the average concentration of a specific micro-environment within one day. As a novelty, by considering time activity patterns and breathing rates in various micro-environments for three age groups, this paper introduces IF and Et into computational fluid dynamic (CFD) simulation to quantify the impacts of street layouts (street width/building height W/H = 1, 1.5, 2), source location, viaduct settings and noise barriers on the source-exposure correlation when realistic CO sources are defined. Narrower streets experience larger P_IF (1.51–5.21 ppm) and CO exposure, and leeward-side buildings always attain higher vehicular pollutant exposure than windward-side. Cases with a viaduct experience smaller P_IF (3.25–1.46 ppm) than cases without a viaduct (P_IF = 5.21–2.23 ppm) if the single ground-level CO source is elevated onto the viaduct. With two CO sources (both ground-level and viaduct-level), daily CO exposure rises 2.80–3.33 times but P_IF only change slightly. Noise barriers above a viaduct raise concentration between barriers, but slightly reduce vehicular exposure in near-road buildings. Because people spend most of their time indoors, vehicular pollutant exposure within near-road buildings can be 6–9 times that at pedestrian level. Although further studies are still required to provide practical guidelines, this paper provides effective methodologies to quantify the impacts of street/viaduct configurations on human exposure for urban design purpose.
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•Intake fraction (IF) and daily CO exposure are adopted to assess human exposure.•Effects of street layouts, viaduct/noise barriers and source locations are studied.•Viaducts attain smaller human exposure if single source is elevated onto viaduct.•Noise barriers raise CO concentration above a viaduct, but reduce indoor exposure.•Indoor exposure to traffic emissions is much greater than that at pedestrian level.
Wider street and urban viaduct with a single elevated source could alleviate indoor exposure and building intake fraction. Adding noise barriers has no significant impact.
High Speed Architecture: HS2's Colne Valley Viaduct Patience, Chris; Jones, Ewan
Structural engineering international : journal of the International Association for Bridge and Structural Engineering (IABSE),
10/2021, Letnik:
31, Številka:
4
Journal Article
This paper describes a study to develop a method for simulating structure borne noise on reinforced concrete viaducts, consisting of structural vibration and acoustic analyses. Results of acoustic ...analyses and measurements found that there was a high possibility of certain frequency bands where structure-borne noise was the main factor generating noise along the railway. Analytical evaluation of the results revealed that reinforcement of the center slab could reduce structure-borne noise by 1.1 dB at the 12.5 m point and 1.8 dB at the 25 m point.
Viaduct Over The Lorupe Ravine Dziedātāja, Indra
IOP conference series. Materials Science and Engineering,
11/2021, Letnik:
1202, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
On the 20th July 2018, it was the 50th anniversary of the day when the Lorupe viaduct was opened. Its idea, design and construction were a significant turning point in bridge construction in ...the whole Soviet Union. In the comparatively small Republic of Latvia it was a unique project that required a lot of boldness and skills of road workers. Therefore, construction of this bridge is memorable, especially since several bridges were built using this technology later in the former Soviet Union. Latvian road workers with their courage, creative and meticulous work implemented a European scale project in difficult, constrained circumstances.
High vehicular pollutants exposure to residents in near-road buildings raises special concerns in micro-scale urban science, as it causes severe health problems for those residents. This paper ...integrates a new parameter, i.e. personal intake fraction (IF_p), into computational fluid dynamics (CFD) simulations to investigate the flow and the resulted personal exposure of two-phase pollutants (CO and particular matters) in three-dimensional (3D) urban-like models. The impacts of street aspect ratios (building height/street width H/W = 0.5–1.5), viaduct settings, noise barriers and pollutant source locations were considered.
3D downward helical flows exist in the secondary streets perpendicular to the parallel approaching wind, which produces lateral pollutant transport across the interface between the main street and secondary streets. Therefore, the overall average IF_p ( ) of CO (∼0.23–0.59 ppm) in our current 3D urban models (H/W = 1) is much smaller than that in two-dimensional (2D) street canyon (∼3.25–5.21 ppm) models. Although narrower 2D street canyons usually present greater , our current 3D urban models do not show this monotone decreasing trend due to the complicated flow structures. of fine particles are always smaller than that of CO. Furthermore, if a single pollutant source is placed on the viaduct, become much smaller than that in cases with a single ground-level source. If the source location changes to the upstream secondary street, significantly decreases due to stronger local wind. Finally, of leeward-side cases usually exceeds that of windward-side cases by several times, but with viaduct settings, this leeward-to-windward ratio significantly decreases.
•Personal Intake Fraction (IF_p) is used for exposure assessment in 3D urban models.•Impacts of aspect ratios in 3D models are more complicated than those in 2D ones.•IF_p in 3D urban models is one order smaller than that in 2D street canyon models.•IF_p of fine particles is always smaller than that of CO due to deposition effect.•The viaduct, noise barriers and source locations are key factors affecting IF_p.
•The impact test results of the scaled model corresponding to the finite element model were used to verify the accuracy of the adopted material models and contact relationships.•Based on the spatial ...complexity of urban overpasses, the dynamic responses and failure mode of the full-bridge model under non-bottom impact were numerically simulated.•Four comparative models were established to study the effect of the bridge model parameters on impact responses.
Urban viaducts are likely to be subjected to non-ground-level vehicle collisions during their service life period. However, current research primarily focus on vehicle impacts on the bottom of bridge piers. In this research, a full-bridge scale model impact test was conducted to validate the accuracy of the finite element (FE) model. Then, LS-DYNA is used to establish refined vehicle-bridge collision FE models. The dynamic responses and failure mode of the pier impacted by the non-bottom vehicle are investigated. Besides, the effects of bridge structure spatial stiffness, superstructure mass, and double-column structure on the impact responses of bridges are analyzed. The results show that vehicle collisions are characterized by a continuous impact action involving multiple components. The damage to the full bridge model is concentrated in the directly impacted double-column pier, where the head-on column sustains three-point bending damage, the indirectly impacted column sustains bending damage at the top and bottom, and the cover beam sustains tensile shear damage. The non-bottom impact significantly increases displacements and bending moments of the pier while causing a substantial decrease in bottom shear. The impact responses of the pier are greatly influenced by the superstructure mass and double-column structure, while the spatial stiffness of the bridge has minimal affection.
In recent years, the urgent need to increase the safety standards of viaducts and bridges—under static and dynamic loading conditions—has required the development of advanced modeling approaches able ...to accurately predict the expected behavior of such infrastructures in a reliable manner. This paper presents a comparison between the adoption of a simplified modeling approach, widely used in the current practice, where the response of the structural system neglects the effects of the soil-structure interaction (SSI) phenomenon (considering the base of the structure fixed at the ground surface) and a rigorous modeling approach that considers the full 3D problem with all the components of the system (superstructure, foundation, and soil), through a finite element model. The pier of a real-world viaduct in central Italy was considered, with the aim of starting from a specific case study with foundation characteristics that are frequently found in viaducts in Italy, to obtain results that can be generalized to a wide range of similar types. Its behavior was evaluated both in the dynamic range of small oscillations and in the field of the seismic response to low and strong motion events. The results show that, in terms of seismic demand, the fixed-based model appears more conservative, but it significantly underestimates both elastic and residual displacements and rotations
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