The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engineer-geologist s...The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engineer-geologist survey been held in railway industry. This paper presents general issues concerning railway construction and operation in permafrost areas. Comprehensive geophysical methods to monitor the development of thawed soils axe considered in detail. The main physical parameters which help define permafrost and thawed soil patches are described. Author of current paper pointed out main factors, allowing predicting potential areas of development of thawed grounds. They offered set non-destructive methods： GPR investigations, seismic survey and elec- tric exploration. Whole sets of geophysical data： electric resistivity, velocity of S-wave and P-wave （and their correlation）, allow us with high confidence specify characteristics and state of soil either under the line of road, or near it. At the same time the meth- od allows to predict direction of further development of thawed ground area.展开更多
The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing.This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen ...The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing.This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen railroad roadbeds and the effects of the freezing and expansion diseases on the roadbeds.This article presents a study of the Shuo-Huang Heavy Duty Railway.Initially,on-site monitoring tests were conducted to analyze the roadbed temperature,water content and deformations due to freezing.Through these tests,the pattern of development of the roadbed freezing and swelling was understood,and the effect of this on the vibration response of the roadbed was investigated.Subsequently,load-free freezing tests were performed to investigate the freezing and expansion features of the roadbed.Through on-site monitoring,it has been determined that the seasonal freezing layer is approximately 0.5 m deep.The depth of the frozen expansion on both sides of the road shows clear differences.The frozen and expansion disease significantly amplifies the vibration acceleration of the roadbed,with a tendency towards low-frequency and high-amplitude vibrations.Through indoor testing,we compared the deformation of frozen specimens and their final freeze and expansion rates at different cold-end temperatures and various initial moisture content levels.We find that the initial moisture content has a greater impact on specimen freezing and expansion.The findings in this paper can be used as a reference for researching and addressing roadbed freezing and expansion problems.展开更多
Support and maintenance of tunnel excavations during operation are critical to ensure the safety and stability of tunnels.This study proposes a specialized support technology for a railroad tunnel in western China,cha...Support and maintenance of tunnel excavations during operation are critical to ensure the safety and stability of tunnels.This study proposes a specialized support technology for a railroad tunnel in western China,characterized by substantial deformation and a limited inherent self-stabilizing capacity.The method involves the application of a foam concrete compressible layer at the inverted arch of the tunnel.The effectiveness of the foam concrete layer in mitigating the effect of the surrounding rock on the tunnel inverted arch structure is investigated by a combination of indoor tests and numerical simulations.The laboratory test results show that the train load has little effect on the compressive performance of the foamed concrete compressible layer,which indicates that the foamed concrete compressible layer can be applied in the tunnel invert.By analyzing the support effect of the established model,it is found that the foam concrete compressible layer can effectively absorb the deformation pressure generated by the surrounding rock and protect the secondary lining structure,when the compressible layer density is 500 kg/m^(3) and the thickness is set to 20 cm,the supporting effect is the best.展开更多
Rail defects can pose significant safety risks in railway operations, raising the need for effective detection methods. Acoustic Emission (AE) technology has shown promise for identifying and monitoring these defects,...Rail defects can pose significant safety risks in railway operations, raising the need for effective detection methods. Acoustic Emission (AE) technology has shown promise for identifying and monitoring these defects, and this study evaluates an advanced on-vehicle AE detection approach using bone-conduct sensors—a solution to improve upon previous AE methods of using on-rail sensor installations, which required extensive, costly on-rail sensor networks with limited effectiveness. In response to these challenges, the study specifically explored bone-conduct sensors mounted directly on the vehicle rather than rails by evaluating AE signals generated by the interaction between rails and the train’s wheels while in motion. In this research, a prototype detection system was developed and tested through initial trials at the Nevada Railroad Museum using a track with pre-damaged welding defects. Further testing was conducted at the Transportation Technology Center Inc. (rebranded as MxV Rail) in Colorado, where the system’s performance was evaluated across various defect types and train speeds. The results indicated that bone-conduct sensors were insufficient for detecting AE signals when mounted on moving vehicles. These findings highlight the limitations of contact-based methods in real-world applications and indicate the need for exploring improved, non-contact approaches.展开更多
Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and proces...Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and process factors during interval operations and can accumulate over multiple intervals.The aim is to enhance the robustness of high-speed rail station arrival and departure track utilization schemes.Design/methodologylapproach-To achieve this objective,the paper simulates actual train operations,incorporating the fluctuations in interval operation times into the utilization of arrival and departure tracks at the station.The Monte Carlo simulation method is adopted to solve this problem.This approach transforms a nonlinear model,which includes constraints from probability distribution functions and is difficult to solve directly,into a linear programming model that is easier to handle.The method then linearly weights two objectives to optimize the solution.Findings-Through the application of Monte Carlo simulation,the study successfully converts the complex nonlinear model with probability distribution function constraints into a manageable linear programming model.By continuously adjusting the weighting coefficients of the linear objectives,the method is able to optimize the Pareto solution.Notably,this approach does not require extensive scene data to obtain a satisfactory Pareto solution set.Originality/value-The paper contributes to the field by introducing a novel method for optimizing high-speed rail station arrival and departure track utilization in the presence of fluctuations in interval operation times.The use of Monte Carlo simulation to transform the problem into a tractable linear programming model represents a significant advancement.Furthermore,the method's ability to produce satisfactory Pareto solutions without relying on extensive data sets adds to its practical value and applicability in real-world scenarios.展开更多
This study investigated the risk of flooding along the Sao Paulo city＇s railway network and showed its latest technologies. To that end, we took into account topographic and hydrological features, as well as possible...This study investigated the risk of flooding along the Sao Paulo city＇s railway network and showed its latest technologies. To that end, we took into account topographic and hydrological features, as well as possible interferences of the flooding phenomenon with the optimal operation of the railway system. When preparing the maps and the flooding risk analysis, we used data from project SRTM （Shuttle Radar Topography Mission） integrated and processed in a GIS （geographical information system）, through version 2.14 of the geoprocessing software ＂QGis＂. Results showed risk exposure for logistics operations of the railway system for the transportation of passengers, especially in the Central and Eastern regions of the city, where there is a higher concentration of points of flooding, thus making it more difficult for passengers to come and go in the greatest city of Brazil.展开更多
BGS was established on July 11th 1835 as the Ordnance Geological Survey after William Buckland,Charles Lyell and Adam Sedgwick stated:“we drew up a joint report in which we endeavoured to state fully our opinion as t...BGS was established on July 11th 1835 as the Ordnance Geological Survey after William Buckland,Charles Lyell and Adam Sedgwick stated:“we drew up a joint report in which we endeavoured to state fully our opinion as to the great advantages which must accrue from such an undertaking,not only as calculated to promote geological science,which alone would be sufficient object,but also as a work of great practical utility bearing on agriculture,mining,road making,the formation of canals and railroads and other branches of national industry.”展开更多
Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete ...Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load.Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.展开更多
The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track ...The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track slab and bridge structure.In order to study the impact of the interface crack on the dynamic response of CRTSⅢballastless track system on bridge,based on the principle of multi-body dynamics theory and ANSYS+SIMPACK co-simulation,the spatial model of vehicle-track-bridge integration considering the longitudinal stiffness of supports,the track structure and interlayer contact characteristics were established.The dynamic characteristics of the system under different conditions of the width,length and position of the interface crack were analysed,and the limited values of the length and width of the cracks at the track slab edge were proposed.The results show that when the self-compacting concrete does not completely void along the transverse direction of the track slab,the crack has little effect on the dynamic characteristics of the vehicle-track-bridge system.However,when the self-compacting concrete is completely hollowed out along the transverse direction of the track slab,the dynamic amplitudes of the system increase.When the crack length is 1.6 m,the wheel load reduction rate reaches 0.769,which exceeds the limit value and threatens the safety of train operation.The vertical acceleration of the track slab increases by 250.1%,which affects the service life of the track system under the train speed of 200 km/h.展开更多
The pollution status and horizontal distribution of heavy metals (Ni, Pb, Cr, Zn, Cu, and Cd) in the soil on railroad side along the Zhengzhou-Putian section of Longxi-Haizhou Railroad were studied by collecting soil ...The pollution status and horizontal distribution of heavy metals (Ni, Pb, Cr, Zn, Cu, and Cd) in the soil on railroad side along the Zhengzhou-Putian section of Longxi-Haizhou Railroad were studied by collecting soil samples along a sampling section perpendicular to the railroad at the distances of 0, 10, 20, 30, 50, 100, 200, 300, and 500 m from the railroad edge. The concentrations of heavy metals in the sampling soils were higher than those of the control site. The concentrations of Pb, Zn, and Cd were found to be the highest in the soils at the railroad edge, and then decreased with increasing distance from the railroad. The highest concentrations of Ni, Cr, and Cu in soils were located at about 10-30 m from the railroad. Compared with the single factor pollution index (SFPI) of heavy metals calculated for the control site, the average SFPI from the sampling sites decreased in the order of Cr > Cd > Pb > Zn > Ni > Cu. There were notable negative correlations between the integral pollution index (IPI) of soil heavy metals at all sampling sites and the distances from the railroad. According to three IPIs calculated from the background values of heavy metals in och-aquic Cambisols, the heavy metal concentrations in the control soil, and the 2nd levels for soil heavy metals in GB15618-1995, the study area could be divided, based on the distances from the railroad, into four pollution zones: heavy pollution zone (0-10 m), medium pollution zone (10-50 m), slight pollution zone (50-100 m), and warning zone (100-500 m), respectively.展开更多
To study the vehicle hunting behavior and its coupling with car body vibrations,a simplified lateral-dynamics-intended railway vehicle model is developed.A two-truck vehicle is modeled as a 17 degrees-of-freedom rigid...To study the vehicle hunting behavior and its coupling with car body vibrations,a simplified lateral-dynamics-intended railway vehicle model is developed.A two-truck vehicle is modeled as a 17 degrees-of-freedom rigid system,into which the car body flexural vibrations of torsion and bending modes are further integrated.The wheel/rail interaction employs a real-time calculation for the Hertzian normal contact,in which the nonlinear curvatures of wheel and rail profiles are presented as functions of wheelset lateral movement and/or yaw rotation.Then the tangential/creep forces are analytically expressed as the Hertzian contact patch geometry,and lead to a continuous and fast calculation compared to a look-up table interpolation.It is shown that the hunting frequencies of the vehicle model and a truck model differ significantly,which verifies the necessity of the whole vehicle model.In the case of low wheel/rail conicity,the hunting frequency increases linearly with vehicle speed,whereas it rises slowly at high speed for a large conicity.Comparison of hunting frequency and damping ratio between various conicities shows that first hunting(car body hunting)may occur when the vehicle is operated at a low speed in a small conicity case,while a second hunting(truck hunting)appears when the vehicle is operated at a high speed in a large conicity case.Stability analysis of linear and nonlinear vehicle models was carried out through coast down method and constant speed simulations.Results tell that the linear one overestimates the lateral vibrating.Whereas the structural vibrations of car body can be ignored in the stability analysis.Compared to existing simplified models for hunting stability study,the proposed simplified vehicle model released limitations in the nonlinear geometries of wheel/rail profiles,and it is suitable for a frequency-domain analysis by deriving the analytical expressions of the normal and tangential wheel/rail contact forces.展开更多
Elpipes are polymer-insulated underground HVDC electric pipelines based on metallic conductors.Elpipes use relatively rigid extruded conductors designed for higher capacity and efficiency that are practical for overhe...Elpipes are polymer-insulated underground HVDC electric pipelines based on metallic conductors.Elpipes use relatively rigid extruded conductors designed for higher capacity and efficiency that are practical for overhead power lines.Rigid insulation may be used.In this paper,we discuss the technical trade-offs for elpipes,and application of elpipes linking load centers to remote dispatchable hydro power,energy storage sites,and large dispatchable loads,to achieve load leveling through non-local storage and dispatchable loads,via the HVDC grid.Elpipes with voltage source converters(VSC) enable placing many AC/DC power taps on a single HVDC loop.It is advantageous to build up a continental scale HVDC grid from local loops that tie together 10-20 taps.展开更多
The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance.Identification and calculation of the tha...The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance.Identification and calculation of the thawing degree of permafrost soils,frost heaving of clays,and groundwater flooding require careful engineering and geological surveying.The paper describes the unique,long-standing experience of the university scientists connected with maintaining the Russian EastSiberian and Trans-Baikal Railways'facilities.Specific features of and requirements for the surveying,depending on the geological and climatic conditions,are identified.展开更多
We evaluate the feasibility of recovering energy from the vibrations of track and sleepers,during passage of a high-speed train,by means of a pendulum harvester.A simple mathematical model of the parametric pendulum i...We evaluate the feasibility of recovering energy from the vibrations of track and sleepers,during passage of a high-speed train,by means of a pendulum harvester.A simple mathematical model of the parametric pendulum is employed to obtain numerical predictions,while measured data of vibration tests during the passage of a Thalys high-speed train are considered as input forcing.Since a sustained rotation is the most energetic motion of a pendulum,the possibility of achieving such state is evaluated,taking into account the influence of initial conditions,damping and other factors.Numerical simulations show that rotating pendulum harvesters with sufficiently low viscous damping could be able to generate a usable average power on the order of 5–6 W per unit.Considering a modular arrangement of devices,such energy is enough to feed variety of rail-side equipment,as wireless sensors or warning light systems.However,a suitable choice of initial conditions could be a difficult task,leading to the need of a control action.展开更多
The history of railway and highway construction in permafrost zones in Russia, the United States, Canada, and China spans more than 110 years. Nonetheless, no railway track or highway has yet been built in such area t...The history of railway and highway construction in permafrost zones in Russia, the United States, Canada, and China spans more than 110 years. Nonetheless, no railway track or highway has yet been built in such area that is impervious to deformation caused by subsidence resulting from the thawing of ice-rich subgrade soils. This paper presents data on the roadbed states of the Trans- baikalian and the Baikal-Amur Railways as well as the Russian ＂AMUR＂ Chita-Khabarovsk Highway. It also discusses the feasi- bility of roadbed stability maintenance using methods based on the reduction of the mean annual ground temperature and roadbed preservation in a permafrost state by means of the natural cooling and heating factors ratio regulation resulting in a reduction of the heat generation in the roadbed and the adjoining area accompanied by an increase of heat consumption with help of the sun-precipitation protective sheds （awnings）, rock covers, dolomite powder （reflective paint）, cooling tube and thermosyphons as well as tower supports and corrugated pipe culverts stability.展开更多
Creosote-treated wooden railroad crossties have been used for more than a century to support steel rails and to transfer load from the rails to the underlying ballast while keeping the rails at the correct gauge. As t...Creosote-treated wooden railroad crossties have been used for more than a century to support steel rails and to transfer load from the rails to the underlying ballast while keeping the rails at the correct gauge. As transportation engineers look for improved service life and environmental performance in railway systems, alternatives to the creosote-treated wooden crosstie are being considered. This paper compares the cradle-to-grave environmental life cycle assessment (LCA) results of creosote-treated wooden railroad crossties with the primary alternative products: concrete and plastic composite (P/C) crossties. This LCA includes a life cycle inventory (LCI) to catalogue the input and output data from crosstie manufacture, service life, and disposition, and a life cycle impact assessment (LCIA) to evaluate greenhouse gas (GHG) emissions, fossil fuel and water use, and emissions with the potential to cause acidification, smog, ecotoxicity, and eutrophication. Comparisons of the products are made at a functional unit of 1.61 kilometers (1.0 mile) of rail-road track per year. This LCA finds that the manufacture, use, and disposition of creosote-treated wooden railroad crossties offers lower fossil fuel and water use and lesser environmental impacts than competing products manufactured of concrete and P/C.展开更多
This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility sys...This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility systems are also increasing,but the railroad electrical facility system in Korea is rapidly aging.To solve this problem,various methodologies are applied to ensure operational reliability and stability for railroad electrical facility systems,but there is a lack of detailed evaluation criteria for railroad electrical facility system maintenance.Also,maintenance items must be selected in a scientific and systematic method.Therefore,railroad electrical facility systems are selected for study.Design StructureMatrix(DSM)is utilized to establish considerations tailored to the maintenance characteristics,and the Fuzzy-TOPSIS methodology is utilized for determining the maintenance detail evaluation item baseline weights,a multi-criteria decision-making problem.Studies show that degradation,insulation items have the highest weight of 14.63%,and capacity items have the lowest weight of 5.34%.The results of this may be contributed to the underlying research in carrying out maintenance activities to ensure the reliability and safety of railroad electrical facility systems.展开更多
In this study, in-situ testing results are given, and the analytical relationship of the vibrations＇ amplitudes inside an em- bankment by the thawing of the subgrade surface of seasonably deep frozen soils is provide...In this study, in-situ testing results are given, and the analytical relationship of the vibrations＇ amplitudes inside an em- bankment by the thawing of the subgrade surface of seasonably deep frozen soils is provided. The peculiarities of the vi- bration waves＇ propagation during the springtime thawing of soils compared to those during the summertime period and the correlation of the vibrations with the under-rail basement moduln~ nf ala^tieitv nro dofinod展开更多
A growing demand for passenger and freight transportation, combined with limited capital to expand the United States （U.S.） rail infrastructure, is creating pressure for a more efficient use of the current line capa...A growing demand for passenger and freight transportation, combined with limited capital to expand the United States （U.S.） rail infrastructure, is creating pressure for a more efficient use of the current line capacity. This is further exacerbated by the fact that most passenger rail services operate on corridors that are shared with freight traffic. A capacity analysis is one alternative to address the situation and there are various approaches, tools, and methodologies available for application. As the U.S. continues to develop higher speed passenger services with similar characteristics to those in European shared-use lines, understanding the common methods and tools used on both continents grows in relevance. There has not as yet been a detailed investigation as to how each continent approaches capacity analysis, and whether any benefits could be gained from cross-pollination. This paper utilizes more than 50 past capacity studies from the U.S. and Europe to describe the different railroad capacity defini- tions and approaches, and then categorizes them, based on each approach. The capacity methods are commonly di- vided into analytical and simulation methods, but this paper also introduces a third, ＂combined simulation- analytical＂ category. The paper concludes that Europeanrail studies are more unified in terms of capacity, concepts, and techniques, while the U.S. studies represent a greater variation in methods, tools, and objectives. The majority of studies on both continents use either simulation or a combined simulation-analytical approach. However, due to the significant differences between operating philosophy and network characteristics of these two rail systems, European studies tend to use timetable-based simulation tools as opposed to the non-timetable-based tools commonly used in the U.S. rail networks. It was also found that validation of studies against actual operations was not typically completed or was limited to comparisons with a base model.展开更多
This paper explores the role of geographical expansion of railroads,one of the most important Fransporta-tion vehicles,in the history of American west development,analyses its implication on the unprecedented mi grati...This paper explores the role of geographical expansion of railroads,one of the most important Fransporta-tion vehicles,in the history of American west development,analyses its implication on the unprecedented mi gration move-ment and the resulted urbanization i n the west and concludes with the fact that the appropriate interference b y the governm-net,especially in the early period,is vital to regional development pra ctice,because of market failure at t he initial stage,infrastructure constructio n conducted by the government always plays as the first impetus to any regional develop-ment process.Only through this brid ge,can some physical factors,such a s population,be attracted to feed th e back-ward area.As a result,cities grow fa st and the region develops well.The e xperience can be shared by all countr ies.Be-sides reviewing the history of west development in America,focusing on t he relationship between railroads e xpansion and urban growth,which was realized thr ough population migration.Acomparison on the particular pattern of regional develop-ment between U.S and China is made as well at the end.It is noted that despite of the common first impetus,govern-ment subsidies and the common final r esult,urbanization,the path for th e America is bottom-up,whereas that for China is top down,that is to say,developme nt should originate from big cities,then to towns,and finally radiate in to rural ar-eas.展开更多
基金Russian Railways,and Nauka-MSURT for financial support
文摘The zones of thawed ground in the permafrost area are most dangerous from engineer-geologist effect point of view. Detection of such zones, as making forecast of their movement is the main task of engineer-geologist survey been held in railway industry. This paper presents general issues concerning railway construction and operation in permafrost areas. Comprehensive geophysical methods to monitor the development of thawed soils axe considered in detail. The main physical parameters which help define permafrost and thawed soil patches are described. Author of current paper pointed out main factors, allowing predicting potential areas of development of thawed grounds. They offered set non-destructive methods： GPR investigations, seismic survey and elec- tric exploration. Whole sets of geophysical data： electric resistivity, velocity of S-wave and P-wave （and their correlation）, allow us with high confidence specify characteristics and state of soil either under the line of road, or near it. At the same time the meth- od allows to predict direction of further development of thawed ground area.
基金funded by the National Natural Science Foundation of China(NSFC)(grant number:52078312).
文摘The freezing and expansion diseases of railroad roadbeds are prevalent in areas that experience seasonal freezing.This study aims to investigate the features of the freezing and expansion mechanism of seasonal frozen railroad roadbeds and the effects of the freezing and expansion diseases on the roadbeds.This article presents a study of the Shuo-Huang Heavy Duty Railway.Initially,on-site monitoring tests were conducted to analyze the roadbed temperature,water content and deformations due to freezing.Through these tests,the pattern of development of the roadbed freezing and swelling was understood,and the effect of this on the vibration response of the roadbed was investigated.Subsequently,load-free freezing tests were performed to investigate the freezing and expansion features of the roadbed.Through on-site monitoring,it has been determined that the seasonal freezing layer is approximately 0.5 m deep.The depth of the frozen expansion on both sides of the road shows clear differences.The frozen and expansion disease significantly amplifies the vibration acceleration of the roadbed,with a tendency towards low-frequency and high-amplitude vibrations.Through indoor testing,we compared the deformation of frozen specimens and their final freeze and expansion rates at different cold-end temperatures and various initial moisture content levels.We find that the initial moisture content has a greater impact on specimen freezing and expansion.The findings in this paper can be used as a reference for researching and addressing roadbed freezing and expansion problems.
基金supported by the National Natural Science Foundation of China under grant number 52179113Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety Grant No.SKLGME 022022,SKLGME-JBGS2401.
文摘Support and maintenance of tunnel excavations during operation are critical to ensure the safety and stability of tunnels.This study proposes a specialized support technology for a railroad tunnel in western China,characterized by substantial deformation and a limited inherent self-stabilizing capacity.The method involves the application of a foam concrete compressible layer at the inverted arch of the tunnel.The effectiveness of the foam concrete layer in mitigating the effect of the surrounding rock on the tunnel inverted arch structure is investigated by a combination of indoor tests and numerical simulations.The laboratory test results show that the train load has little effect on the compressive performance of the foamed concrete compressible layer,which indicates that the foamed concrete compressible layer can be applied in the tunnel invert.By analyzing the support effect of the established model,it is found that the foam concrete compressible layer can effectively absorb the deformation pressure generated by the surrounding rock and protect the secondary lining structure,when the compressible layer density is 500 kg/m^(3) and the thickness is set to 20 cm,the supporting effect is the best.
文摘Rail defects can pose significant safety risks in railway operations, raising the need for effective detection methods. Acoustic Emission (AE) technology has shown promise for identifying and monitoring these defects, and this study evaluates an advanced on-vehicle AE detection approach using bone-conduct sensors—a solution to improve upon previous AE methods of using on-rail sensor installations, which required extensive, costly on-rail sensor networks with limited effectiveness. In response to these challenges, the study specifically explored bone-conduct sensors mounted directly on the vehicle rather than rails by evaluating AE signals generated by the interaction between rails and the train’s wheels while in motion. In this research, a prototype detection system was developed and tested through initial trials at the Nevada Railroad Museum using a track with pre-damaged welding defects. Further testing was conducted at the Transportation Technology Center Inc. (rebranded as MxV Rail) in Colorado, where the system’s performance was evaluated across various defect types and train speeds. The results indicated that bone-conduct sensors were insufficient for detecting AE signals when mounted on moving vehicles. These findings highlight the limitations of contact-based methods in real-world applications and indicate the need for exploring improved, non-contact approaches.
文摘Purpose-The purpose of this paper is to eliminate the fluctuations in train arrival and departure times caused by skewed distributions in interval operation times.These fluctuations arise from random origin and process factors during interval operations and can accumulate over multiple intervals.The aim is to enhance the robustness of high-speed rail station arrival and departure track utilization schemes.Design/methodologylapproach-To achieve this objective,the paper simulates actual train operations,incorporating the fluctuations in interval operation times into the utilization of arrival and departure tracks at the station.The Monte Carlo simulation method is adopted to solve this problem.This approach transforms a nonlinear model,which includes constraints from probability distribution functions and is difficult to solve directly,into a linear programming model that is easier to handle.The method then linearly weights two objectives to optimize the solution.Findings-Through the application of Monte Carlo simulation,the study successfully converts the complex nonlinear model with probability distribution function constraints into a manageable linear programming model.By continuously adjusting the weighting coefficients of the linear objectives,the method is able to optimize the Pareto solution.Notably,this approach does not require extensive scene data to obtain a satisfactory Pareto solution set.Originality/value-The paper contributes to the field by introducing a novel method for optimizing high-speed rail station arrival and departure track utilization in the presence of fluctuations in interval operation times.The use of Monte Carlo simulation to transform the problem into a tractable linear programming model represents a significant advancement.Furthermore,the method's ability to produce satisfactory Pareto solutions without relying on extensive data sets adds to its practical value and applicability in real-world scenarios.
文摘This study investigated the risk of flooding along the Sao Paulo city＇s railway network and showed its latest technologies. To that end, we took into account topographic and hydrological features, as well as possible interferences of the flooding phenomenon with the optimal operation of the railway system. When preparing the maps and the flooding risk analysis, we used data from project SRTM （Shuttle Radar Topography Mission） integrated and processed in a GIS （geographical information system）, through version 2.14 of the geoprocessing software ＂QGis＂. Results showed risk exposure for logistics operations of the railway system for the transportation of passengers, especially in the Central and Eastern regions of the city, where there is a higher concentration of points of flooding, thus making it more difficult for passengers to come and go in the greatest city of Brazil.
文摘BGS was established on July 11th 1835 as the Ordnance Geological Survey after William Buckland,Charles Lyell and Adam Sedgwick stated:“we drew up a joint report in which we endeavoured to state fully our opinion as to the great advantages which must accrue from such an undertaking,not only as calculated to promote geological science,which alone would be sufficient object,but also as a work of great practical utility bearing on agriculture,mining,road making,the formation of canals and railroads and other branches of national industry.”
基金Project(51378503)supported by the National Natural Science Foundation of ChinaProject(2014M552158)supported by China Postdoctoral Science Foundation
文摘Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube(CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a(77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail(CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load.Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.
基金Project(2017YFB1201204)supported by National Key R&D Program of China。
文摘The damage of the self-compacting concrete in CRTSⅢslab ballastless track on bridge will lead to a partial void of the track slab,which will affect the comfort and safety of the train and the durability of the track slab and bridge structure.In order to study the impact of the interface crack on the dynamic response of CRTSⅢballastless track system on bridge,based on the principle of multi-body dynamics theory and ANSYS+SIMPACK co-simulation,the spatial model of vehicle-track-bridge integration considering the longitudinal stiffness of supports,the track structure and interlayer contact characteristics were established.The dynamic characteristics of the system under different conditions of the width,length and position of the interface crack were analysed,and the limited values of the length and width of the cracks at the track slab edge were proposed.The results show that when the self-compacting concrete does not completely void along the transverse direction of the track slab,the crack has little effect on the dynamic characteristics of the vehicle-track-bridge system.However,when the self-compacting concrete is completely hollowed out along the transverse direction of the track slab,the dynamic amplitudes of the system increase.When the crack length is 1.6 m,the wheel load reduction rate reaches 0.769,which exceeds the limit value and threatens the safety of train operation.The vertical acceleration of the track slab increases by 250.1%,which affects the service life of the track system under the train speed of 200 km/h.
基金supported by the National Natural Science Foundation of China (No.30570301).
文摘The pollution status and horizontal distribution of heavy metals (Ni, Pb, Cr, Zn, Cu, and Cd) in the soil on railroad side along the Zhengzhou-Putian section of Longxi-Haizhou Railroad were studied by collecting soil samples along a sampling section perpendicular to the railroad at the distances of 0, 10, 20, 30, 50, 100, 200, 300, and 500 m from the railroad edge. The concentrations of heavy metals in the sampling soils were higher than those of the control site. The concentrations of Pb, Zn, and Cd were found to be the highest in the soils at the railroad edge, and then decreased with increasing distance from the railroad. The highest concentrations of Ni, Cr, and Cu in soils were located at about 10-30 m from the railroad. Compared with the single factor pollution index (SFPI) of heavy metals calculated for the control site, the average SFPI from the sampling sites decreased in the order of Cr > Cd > Pb > Zn > Ni > Cu. There were notable negative correlations between the integral pollution index (IPI) of soil heavy metals at all sampling sites and the distances from the railroad. According to three IPIs calculated from the background values of heavy metals in och-aquic Cambisols, the heavy metal concentrations in the control soil, and the 2nd levels for soil heavy metals in GB15618-1995, the study area could be divided, based on the distances from the railroad, into four pollution zones: heavy pollution zone (0-10 m), medium pollution zone (10-50 m), slight pollution zone (50-100 m), and warning zone (100-500 m), respectively.
基金The project was supported by the National Natural Science Foundation of China(Grants 51805451,U1934202,and U2034210)the Sichuan Science and Technology Plan Project(Grant 2020YJ0074)+1 种基金the Fundamental Research Funds for the Central Universities(Grant 2682019CX43)the TPL Independent R&D Project(Grants 2018TPL_T08 and 2019TPL_T15).
文摘To study the vehicle hunting behavior and its coupling with car body vibrations,a simplified lateral-dynamics-intended railway vehicle model is developed.A two-truck vehicle is modeled as a 17 degrees-of-freedom rigid system,into which the car body flexural vibrations of torsion and bending modes are further integrated.The wheel/rail interaction employs a real-time calculation for the Hertzian normal contact,in which the nonlinear curvatures of wheel and rail profiles are presented as functions of wheelset lateral movement and/or yaw rotation.Then the tangential/creep forces are analytically expressed as the Hertzian contact patch geometry,and lead to a continuous and fast calculation compared to a look-up table interpolation.It is shown that the hunting frequencies of the vehicle model and a truck model differ significantly,which verifies the necessity of the whole vehicle model.In the case of low wheel/rail conicity,the hunting frequency increases linearly with vehicle speed,whereas it rises slowly at high speed for a large conicity.Comparison of hunting frequency and damping ratio between various conicities shows that first hunting(car body hunting)may occur when the vehicle is operated at a low speed in a small conicity case,while a second hunting(truck hunting)appears when the vehicle is operated at a high speed in a large conicity case.Stability analysis of linear and nonlinear vehicle models was carried out through coast down method and constant speed simulations.Results tell that the linear one overestimates the lateral vibrating.Whereas the structural vibrations of car body can be ignored in the stability analysis.Compared to existing simplified models for hunting stability study,the proposed simplified vehicle model released limitations in the nonlinear geometries of wheel/rail profiles,and it is suitable for a frequency-domain analysis by deriving the analytical expressions of the normal and tangential wheel/rail contact forces.
文摘Elpipes are polymer-insulated underground HVDC electric pipelines based on metallic conductors.Elpipes use relatively rigid extruded conductors designed for higher capacity and efficiency that are practical for overhead power lines.Rigid insulation may be used.In this paper,we discuss the technical trade-offs for elpipes,and application of elpipes linking load centers to remote dispatchable hydro power,energy storage sites,and large dispatchable loads,to achieve load leveling through non-local storage and dispatchable loads,via the HVDC grid.Elpipes with voltage source converters(VSC) enable placing many AC/DC power taps on a single HVDC loop.It is advantageous to build up a continental scale HVDC grid from local loops that tie together 10-20 taps.
文摘The operation of a railway track in cold regions results in the premature deformation of subgrade soils caused by significant temperature fluctuations and ecological imbalance.Identification and calculation of the thawing degree of permafrost soils,frost heaving of clays,and groundwater flooding require careful engineering and geological surveying.The paper describes the unique,long-standing experience of the university scientists connected with maintaining the Russian EastSiberian and Trans-Baikal Railways'facilities.Specific features of and requirements for the surveying,depending on the geological and climatic conditions,are identified.
基金support of Secretary of Science and Technology of UTN, CONICETthe National Agency for Scientific and Technological Promotion and Engineering Department of UNS
文摘We evaluate the feasibility of recovering energy from the vibrations of track and sleepers,during passage of a high-speed train,by means of a pendulum harvester.A simple mathematical model of the parametric pendulum is employed to obtain numerical predictions,while measured data of vibration tests during the passage of a Thalys high-speed train are considered as input forcing.Since a sustained rotation is the most energetic motion of a pendulum,the possibility of achieving such state is evaluated,taking into account the influence of initial conditions,damping and other factors.Numerical simulations show that rotating pendulum harvesters with sufficiently low viscous damping could be able to generate a usable average power on the order of 5–6 W per unit.Considering a modular arrangement of devices,such energy is enough to feed variety of rail-side equipment,as wireless sensors or warning light systems.However,a suitable choice of initial conditions could be a difficult task,leading to the need of a control action.
文摘The history of railway and highway construction in permafrost zones in Russia, the United States, Canada, and China spans more than 110 years. Nonetheless, no railway track or highway has yet been built in such area that is impervious to deformation caused by subsidence resulting from the thawing of ice-rich subgrade soils. This paper presents data on the roadbed states of the Trans- baikalian and the Baikal-Amur Railways as well as the Russian ＂AMUR＂ Chita-Khabarovsk Highway. It also discusses the feasi- bility of roadbed stability maintenance using methods based on the reduction of the mean annual ground temperature and roadbed preservation in a permafrost state by means of the natural cooling and heating factors ratio regulation resulting in a reduction of the heat generation in the roadbed and the adjoining area accompanied by an increase of heat consumption with help of the sun-precipitation protective sheds （awnings）, rock covers, dolomite powder （reflective paint）, cooling tube and thermosyphons as well as tower supports and corrugated pipe culverts stability.
文摘Creosote-treated wooden railroad crossties have been used for more than a century to support steel rails and to transfer load from the rails to the underlying ballast while keeping the rails at the correct gauge. As transportation engineers look for improved service life and environmental performance in railway systems, alternatives to the creosote-treated wooden crosstie are being considered. This paper compares the cradle-to-grave environmental life cycle assessment (LCA) results of creosote-treated wooden railroad crossties with the primary alternative products: concrete and plastic composite (P/C) crossties. This LCA includes a life cycle inventory (LCI) to catalogue the input and output data from crosstie manufacture, service life, and disposition, and a life cycle impact assessment (LCIA) to evaluate greenhouse gas (GHG) emissions, fossil fuel and water use, and emissions with the potential to cause acidification, smog, ecotoxicity, and eutrophication. Comparisons of the products are made at a functional unit of 1.61 kilometers (1.0 mile) of rail-road track per year. This LCA finds that the manufacture, use, and disposition of creosote-treated wooden railroad crossties offers lower fossil fuel and water use and lesser environmental impacts than competing products manufactured of concrete and P/C.
基金This research was supported by a grant from R&D Program of the Korea Railroad Research Institute,Republic of Korea.
文摘This paper is on the suggestion of maintenance items for electric railway facility systems.With the recent increase in the use of electric locomotives,the utilization and importance of railroad electrical facility systems are also increasing,but the railroad electrical facility system in Korea is rapidly aging.To solve this problem,various methodologies are applied to ensure operational reliability and stability for railroad electrical facility systems,but there is a lack of detailed evaluation criteria for railroad electrical facility system maintenance.Also,maintenance items must be selected in a scientific and systematic method.Therefore,railroad electrical facility systems are selected for study.Design StructureMatrix(DSM)is utilized to establish considerations tailored to the maintenance characteristics,and the Fuzzy-TOPSIS methodology is utilized for determining the maintenance detail evaluation item baseline weights,a multi-criteria decision-making problem.Studies show that degradation,insulation items have the highest weight of 14.63%,and capacity items have the lowest weight of 5.34%.The results of this may be contributed to the underlying research in carrying out maintenance activities to ensure the reliability and safety of railroad electrical facility systems.
文摘In this study, in-situ testing results are given, and the analytical relationship of the vibrations＇ amplitudes inside an em- bankment by the thawing of the subgrade surface of seasonably deep frozen soils is provided. The peculiarities of the vi- bration waves＇ propagation during the springtime thawing of soils compared to those during the summertime period and the correlation of the vibrations with the under-rail basement moduln~ nf ala^tieitv nro dofinod
文摘A growing demand for passenger and freight transportation, combined with limited capital to expand the United States （U.S.） rail infrastructure, is creating pressure for a more efficient use of the current line capacity. This is further exacerbated by the fact that most passenger rail services operate on corridors that are shared with freight traffic. A capacity analysis is one alternative to address the situation and there are various approaches, tools, and methodologies available for application. As the U.S. continues to develop higher speed passenger services with similar characteristics to those in European shared-use lines, understanding the common methods and tools used on both continents grows in relevance. There has not as yet been a detailed investigation as to how each continent approaches capacity analysis, and whether any benefits could be gained from cross-pollination. This paper utilizes more than 50 past capacity studies from the U.S. and Europe to describe the different railroad capacity defini- tions and approaches, and then categorizes them, based on each approach. The capacity methods are commonly di- vided into analytical and simulation methods, but this paper also introduces a third, ＂combined simulation- analytical＂ category. The paper concludes that Europeanrail studies are more unified in terms of capacity, concepts, and techniques, while the U.S. studies represent a greater variation in methods, tools, and objectives. The majority of studies on both continents use either simulation or a combined simulation-analytical approach. However, due to the significant differences between operating philosophy and network characteristics of these two rail systems, European studies tend to use timetable-based simulation tools as opposed to the non-timetable-based tools commonly used in the U.S. rail networks. It was also found that validation of studies against actual operations was not typically completed or was limited to comparisons with a base model.
文摘This paper explores the role of geographical expansion of railroads,one of the most important Fransporta-tion vehicles,in the history of American west development,analyses its implication on the unprecedented mi gration move-ment and the resulted urbanization i n the west and concludes with the fact that the appropriate interference b y the governm-net,especially in the early period,is vital to regional development pra ctice,because of market failure at t he initial stage,infrastructure constructio n conducted by the government always plays as the first impetus to any regional develop-ment process.Only through this brid ge,can some physical factors,such a s population,be attracted to feed th e back-ward area.As a result,cities grow fa st and the region develops well.The e xperience can be shared by all countr ies.Be-sides reviewing the history of west development in America,focusing on t he relationship between railroads e xpansion and urban growth,which was realized thr ough population migration.Acomparison on the particular pattern of regional develop-ment between U.S and China is made as well at the end.It is noted that despite of the common first impetus,govern-ment subsidies and the common final r esult,urbanization,the path for th e America is bottom-up,whereas that for China is top down,that is to say,developme nt should originate from big cities,then to towns,and finally radiate in to rural ar-eas.
