The Sichuan-Tibet transportation corridor is prone to numerous active faults and frequent strong earthquakes.While extensive studies have individually explored the effect of active faults and strong earthquakes on dif...The Sichuan-Tibet transportation corridor is prone to numerous active faults and frequent strong earthquakes.While extensive studies have individually explored the effect of active faults and strong earthquakes on different engineering structures,their combined effect remains unclear.This research employed multiple physical model tests to investigate the dynamic response of various engineering structures,including tunnels,bridges,and embankments,under the simultaneous influence of cumulative earthquakes and stick-slip misalignment of an active fault.The prototype selected for this study was the Kanding No.2 tunnel,which crosses the Yunongxi fault zone within the Sichuan-Tibet transportation corridor.The results demonstrated that the tunnel,bridge,and embankment exhibited amplification in response to the input seismic wave,with the amplification effect gradually decreasing as the input peak ground acceleration(PGA)increased.The PGAs of different engineering structures were weakened by the fault rupture zone.Nevertheless,the misalignment of the active fault may decrease the overall stiffness of the engineering structure,leading to more severe damage,with a small contribution from seismic vibration.Additionally,the seismic vibration effect might be enlarged with the height of the engineering structure,and the tunnel is supposed to have a smaller PGA and lower dynamic earth pressure compared to bridges and embankments in strong earthquake zones crossing active faults.The findings contribute valuable insights for evaluating the dynamic response of various engineering structures crossing an active fault and provide an experimental reference for secure engineering design in the challenging conditions of the Sichuan-Tibet transportation corridor.展开更多
The Sichuan-Tibet transportation corridor is located at the eastern margin of the Qinghai-Tibet Plateau,where the complex topography and geological conditions,developed geo-hazards have severely restricted the plannin...The Sichuan-Tibet transportation corridor is located at the eastern margin of the Qinghai-Tibet Plateau,where the complex topography and geological conditions,developed geo-hazards have severely restricted the planning and construction of major projects.For the long-term prevention and early control of regional seismic landslides,based on analyzing seismic landslide characteristics,the Newmark model was used to carry out the potential seismic landslide hazard assessment with a 50-year beyond probability 10%.The results show that the high seismic landslide hazard is mainly distributed along large active tectonic belts and deep-cut river canyons,and are significantly affected by the active tectonics.The low seismic landslide hazard is mainly distributed in the flat terrain such as the Quaternary basins,broad river valleys,and plateau planation planes.The major east-west linear projects mainly pass through five areas with high seismic landslide hazard:Luding-Kangding section,Yajiang-Xinlong(Yalong river)section,Batang-Baiyu(Jinsha river)section,Basu(Nujiang river)section,and Bomi-Linzhi(eastern Himalaya syntaxis)section.The seismic action of the Bomi-Linzhi section can also induce high-risk geo-hazard chains such as the high-level glacial lake breaks and glacial debris flows.The early prevention of seismic landslides should be strengthened in the areas with high seismic landslide hazard.展开更多
The Chengdu-Ya’an section of Sichuan-Tibet Railway(STR),which has already started operation,is taken as an example.First,we apply the weighted average travel time and gravity model to analyze the accessibility of the...The Chengdu-Ya’an section of Sichuan-Tibet Railway(STR),which has already started operation,is taken as an example.First,we apply the weighted average travel time and gravity model to analyze the accessibility of the site cities and the economic link intensity among them,with visualization by ArcGIS.Then,we use the difference-in-differences model with panel data of three cities from 2018 to 2019 to test the impact of the Chengdu-Ya’an section on regional urbanization along the route.The results show that the opening of the Chengdu-Ya’an section has significantly improved the accessibility and economic link of areas along the line and promoted regional economic development and urbanization.It is expected that the opening of the entire line of STR will have more significant impacts,which requires continuous research and attention in the future.展开更多
Identifying the ecological vulnerability of the sensitive and fragile ecosystem of the Ya’anQamdo section along the southern route of the Sichuan-Tibet transport corridor is of paramount importance to reduce environm...Identifying the ecological vulnerability of the sensitive and fragile ecosystem of the Ya’anQamdo section along the southern route of the Sichuan-Tibet transport corridor is of paramount importance to reduce environmental damage resulting from infrastructure construction.This paper divided the Ya’an-Qamdo transport section into 22subzones according to their ecological environment characteristics.Based on the vulnerability evaluation model established by the fuzzy matter-element analysis method,the eight main assessment indicators of ecological vulnerability were windstorm,rainstorm,snowstorm,extreme temperature,extreme air pressure,geological hazard,natural conditions,and social resources.The rating and ranking of vulnerability in each subzone were based on the weight of the judgment indicators.Scientific processes were used to verify the rationality of both the indicators themselves and their weights.The results of this study show that subzone 9,located in the subalpine cold and humid forest and scrubland zone,is the most vulnerable,and subzone 1,located in the low-to mid-land warm and humid forest zone,is the least vulnerable.The conclusion of the study suggests that targeted measures of ecological protection should be formulated before development and construction of major transportation infrastructure.Construction should evade the most vulnerable areas,and in-depth research on ecological restoration should be carried out in low-to midvulnerability areas so that the ecological environment along the route can be protected effectively for sustainable economic and social development.展开更多
Accurate evaluation of landslide susceptibility is very important to ensure the safe operation of mountain highways.The Sichuan-Tibet Highway,which traverses the east of the Tibetan Plateau,frequently encounters natur...Accurate evaluation of landslide susceptibility is very important to ensure the safe operation of mountain highways.The Sichuan-Tibet Highway,which traverses the east of the Tibetan Plateau,frequently encounters natural hazards.Previous studies generally use statistical methods to analyze the hazards along the Sichuan-Tibet Highway.In this research,we present two road factors,namely aspect to road and road profile to increase the accuracy of landslide susceptibility mapping by considering the influence of landslide movement direction on road.First,the aspect to road,which represents the impact of different landslide movement directions on the highway,was extracted by combining road direction with mountain aspect.Then,the road profile,which reflects the subgrade structure between the road and surrounding mountains,was extracted according to the terrain data.Finally,the landslide susceptibility maps were produced based on the random forest(RF)method by using 473 landslides and 10 conditioning factors,including road factors(aspect to road,road profile)and primitive factors(slope,aspect,curvature,relief amplitude,peak ground acceleration,crustal movement velocity,faults,rainfall).The area under the receiver operating characteristic curve(AUC)and the Gini importance were used to evaluate the performance of proposed road factors.The AUC values on two groups that add road factors and only use primitive factors were 0.8517 and 0.8243,respectively.The Gini importance indicated that road profile(0.123)and aspect to road(0.116)have a significant contribution to landslides compared with the primitive factors.The results of multi-collinearity analysis and frequency ratio confirmed the suitability of the road factors for predicting hazards along the highway.展开更多
SIXTY-EIGHT years ago, the Song of the Erlang Mountain was a smash hit all over China. It is an ode to the heroic builders of the highway between Sichuan and Tibet, which cuts through towering mountains and spans bill...SIXTY-EIGHT years ago, the Song of the Erlang Mountain was a smash hit all over China. It is an ode to the heroic builders of the highway between Sichuan and Tibet, which cuts through towering mountains and spans billowy rivers.展开更多
The anomalous movements of glaciers cause disasters,such as debrisflows and landslides.It is very important to assess the glacier movements and their future trends.Glacier velocity refers to movement process.The curre...The anomalous movements of glaciers cause disasters,such as debrisflows and landslides.It is very important to assess the glacier movements and their future trends.Glacier velocity refers to movement process.The current research aims to analyse past and current spatiotemporal changes in glacier velocity.No study has used neural network model to conduct a spatiotemporal prediction for glacier velocity.Therefore,this paper selected typical mountain glaciers G2 and G5 along the Sichuan-Tibet Railway as research objects and constructed the Convolutional Gate Recurrent Unit(ConvGRU)spatiotemporal prediction model based on 1988–2018 Landsat data to predict velocities in 2019–2028,and analysed the future trends of G2 and G5.The evaluation indexes met the model requirements to a large extent,quantitatively showing that the model has high accuracy and can successfully capture thefluctuation changes in time series data of glacier velocity.The mean deviations of G2 and G5 were 0.09 and-0.47 m/yr,respectively,reflecting the high reliability of the model applied to extraction of glacier velocity.The velocities of G2 and G5 showed a slow downtrend withfluctuations;that is,they will not cause damage to the construction and operation of the Sichuan-Tibet Railway in the short term.展开更多
Based on multiresource high-resolution in situ and satellite merged observations along with model simulations from the Coordinated Regional Climate Downscaling Experiment(CORDEX),this study first investigated historic...Based on multiresource high-resolution in situ and satellite merged observations along with model simulations from the Coordinated Regional Climate Downscaling Experiment(CORDEX),this study first investigated historical changes in extreme temperature and precipitation during the period of 1979-2018 in areas along the Sichuan-Tibet Railway,and then projected the future changes in the frequency and intensity of extreme temperature and precipitation under the RCP(Representative Concentration Pathway)4.5 and 8.5 scenarios.This paper is expected to enhance our understanding of the spatiotemporal variability in the extreme temperature and precipitation along the Sichuan-Tibet Railway,and to provide scientific basis to advance the Sichuan-Tibet Railway construction and operation.The results show that temperatures in the Sichuan-Tibet region display a noticeable warming trend in the past 40 years,and the increase of minimum temperature is significantly higher than that of maximum temperature in the northwest of the region.Significant increase of precipitation is found mainly over the northwest of the Tibetan Plateau.Except for Lhasa and its surrounding areas,precipitation over other areas along the Sichuan-Tibet Railway shows no significant change in the past 40 years,as indicated in five datasets;however,precipitation along the railway has shown a remarkable decrease in the past 20 years in the TRMM satellite dataset.The warm days and nights have clearly increased by 6 and 5 day decade1-for 1979-2019,while cold days and nights have markedly decreased by about 6.6 and 3.6 day decade-1,respectively.In the past 20 years,the areas with increased precipitation from very wet days and extremely wet days are mainly distributed to the north of the Sichuan-Tibet Railway,while in the areas along the railway itself,the very wet days and extremely wet days are decreasing.Under RCPs 4.5 and 8.5,the temperature in the Sichuan-Tibet region will increase significantly,and the frequency of extreme high(low)temperature events in the late 21 st century(2070-2099)will greatly increase(decrease)by about 50%-80%(10%)compared with occurrences in the late 20 th century(1970-1999).Meanwhile,the frequency of very wet days and extremely wet days in the Sichuan-Tibet region will increase by about 2%-19% and 2%-5%,respectively,and the areas along the Sichuan-Tibet Railway will be affected by more extreme high temperature and extreme precipitation events.展开更多
Safety is one of the most critical themes in any large-scale railway construction project.Recognizing the importance of safety in railway engineering,practitioners and researchers have proposed various standards and p...Safety is one of the most critical themes in any large-scale railway construction project.Recognizing the importance of safety in railway engineering,practitioners and researchers have proposed various standards and procedures to ensure safety in construction activities.In this study,we first review four critical research areas of risk warning technologies and emergency response mechanisms in railway construction,namely,(i)risk identification methods of large-scale railway construction projects,(ii)risk management of large-scale railway construction,(iii)emergency response planning and management,and(iv)emergency response and rescue mechanisms.After reviewing the existing studies,we present four corresponding research areas and recommendations on the Sichuan-Tibet Railway construction.This study aims to inject new significant theoretical elements into the decision-making process and construction of this railway project in China.展开更多
Spatial and temporal temperature variations are critical for concrete box girders,and non-uniform temperature distributions induced by solar radiation depend on the structural shapes and shadows cast on them.There hav...Spatial and temporal temperature variations are critical for concrete box girders,and non-uniform temperature distributions induced by solar radiation depend on the structural shapes and shadows cast on them.There have been many studies of temperature distributions and temperature gradients of concrete box girders,but few have considered a high altitude plateau climatic environment.In this study,the nonlinear temperature distributions of concrete box girders in the Sichuan-Tibet railway caused by solar radiation were investigated based on experimental analysis,real-time shadow-selection algorithm,and finite element method.Furthermore,a vertical temperature gradient model of the concrete box girders was obtained.The vertical temperature gradient values first rise,then decrease,and finally rise again from Chengdu to Lhasa,with samples forming a normal distribution.The recommended vertical temperature gradient value was 25℃with a confidence interval of 95%.This provides a reference for the design and maintenance of concrete box girders on the Sichuan-Tibet railway.展开更多
The Sichuan-Tibet Railway is facing extraordinary challenges in terms of construction,operation,and maintenance because of its extremely complicated natural environment and geological conditions.Consequently,counterme...The Sichuan-Tibet Railway is facing extraordinary challenges in terms of construction,operation,and maintenance because of its extremely complicated natural environment and geological conditions.Consequently,countermeasures are necessary and urgent to ensure its safety and reliability in the whole life cycle.This study proposes a novel reliability framework to guarantee the ideal operation state of the Sichuan-Tibet Railway.Reliability application in many fields are summarized,including military equipment,rail locomotive,and railway engineering.Given the fact that the Sichuan-Tibet Railway is a complex giant system,Nine-Connotation was summarized(i.e.,safety,inherent reliability,testability,maintainability,supportability,environmental adaptability,predictability,resilience,and durability)under the goal of optimizing the operational efficiency.On the basis of the concept of the Nine-Connotation and the understanding of reliability transmission mechanism,the framework of reliability for the Sichuan-Tibet Railway was established,which can facilitate a comprehensive and real-time evaluation of all situations with a clear hierarchy.The proposed framework is composed of a resilience management system,an integrated technology system,and a dynamic reliability assessment system.The pathway for its application on railway construction was developed in this study.The proposed framework can assist in well-informed decisions for the construction,as well as the operation of the Sichuan-Tibet Railway.On the basis of a top-down design concept for the first time,this study emphasizes the railway's availability and validity to complete the assigned tasks as a whole,that is,operational efficiency.It also shows the reliability transmission and control mechanism of the railway's giant complex system,innovating and establishing the management principle of great safety and great reliability over the life cycle.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.41825018,41977248,42207219)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant No.2019QZKK0904)。
文摘The Sichuan-Tibet transportation corridor is prone to numerous active faults and frequent strong earthquakes.While extensive studies have individually explored the effect of active faults and strong earthquakes on different engineering structures,their combined effect remains unclear.This research employed multiple physical model tests to investigate the dynamic response of various engineering structures,including tunnels,bridges,and embankments,under the simultaneous influence of cumulative earthquakes and stick-slip misalignment of an active fault.The prototype selected for this study was the Kanding No.2 tunnel,which crosses the Yunongxi fault zone within the Sichuan-Tibet transportation corridor.The results demonstrated that the tunnel,bridge,and embankment exhibited amplification in response to the input seismic wave,with the amplification effect gradually decreasing as the input peak ground acceleration(PGA)increased.The PGAs of different engineering structures were weakened by the fault rupture zone.Nevertheless,the misalignment of the active fault may decrease the overall stiffness of the engineering structure,leading to more severe damage,with a small contribution from seismic vibration.Additionally,the seismic vibration effect might be enlarged with the height of the engineering structure,and the tunnel is supposed to have a smaller PGA and lower dynamic earth pressure compared to bridges and embankments in strong earthquake zones crossing active faults.The findings contribute valuable insights for evaluating the dynamic response of various engineering structures crossing an active fault and provide an experimental reference for secure engineering design in the challenging conditions of the Sichuan-Tibet transportation corridor.
基金supported by the National Natural Science Foundation of China(42277180)China Geological Survey Project(DD20221816)+1 种基金National Key Research and Development Program of China(2021YFB2301403-5)State Key Laboratory of Resources and Environmental Information System.
文摘The Sichuan-Tibet transportation corridor is located at the eastern margin of the Qinghai-Tibet Plateau,where the complex topography and geological conditions,developed geo-hazards have severely restricted the planning and construction of major projects.For the long-term prevention and early control of regional seismic landslides,based on analyzing seismic landslide characteristics,the Newmark model was used to carry out the potential seismic landslide hazard assessment with a 50-year beyond probability 10%.The results show that the high seismic landslide hazard is mainly distributed along large active tectonic belts and deep-cut river canyons,and are significantly affected by the active tectonics.The low seismic landslide hazard is mainly distributed in the flat terrain such as the Quaternary basins,broad river valleys,and plateau planation planes.The major east-west linear projects mainly pass through five areas with high seismic landslide hazard:Luding-Kangding section,Yajiang-Xinlong(Yalong river)section,Batang-Baiyu(Jinsha river)section,Basu(Nujiang river)section,and Bomi-Linzhi(eastern Himalaya syntaxis)section.The seismic action of the Bomi-Linzhi section can also induce high-risk geo-hazard chains such as the high-level glacial lake breaks and glacial debris flows.The early prevention of seismic landslides should be strengthened in the areas with high seismic landslide hazard.
基金funded by the National Social Science Fund West Project(19XSH025)the Ministry of Education Fund for Humanities and Social Sciences Youth Project(20YJCZH153)the Soft science Project of Science and Technology Department of Sichuan Province(2020JDR0252).
文摘The Chengdu-Ya’an section of Sichuan-Tibet Railway(STR),which has already started operation,is taken as an example.First,we apply the weighted average travel time and gravity model to analyze the accessibility of the site cities and the economic link intensity among them,with visualization by ArcGIS.Then,we use the difference-in-differences model with panel data of three cities from 2018 to 2019 to test the impact of the Chengdu-Ya’an section on regional urbanization along the route.The results show that the opening of the Chengdu-Ya’an section has significantly improved the accessibility and economic link of areas along the line and promoted regional economic development and urbanization.It is expected that the opening of the entire line of STR will have more significant impacts,which requires continuous research and attention in the future.
基金sponsored by the National Natural Science Foundation of China under the project“Research on Urban Spatial Coupling Mechanism Between Urban Epidemic Spreading and Vulnerability and Planning Response in Chengdu-Chongqing Area”(Grant No.52078423)“Research on Coupling Mechanism of Production-Life-Ecology Space and Planning Methods–Case Studies in Earthquake Disaster Areas of Sichuan”(Grant No.51678487)the Major Program of Sichuan Provincial Scientific Research under the Project of“Research and Demonstration of Resilient Collaborative Planning and Design for Park Cities”(Grant No.2020YFS0054)。
文摘Identifying the ecological vulnerability of the sensitive and fragile ecosystem of the Ya’anQamdo section along the southern route of the Sichuan-Tibet transport corridor is of paramount importance to reduce environmental damage resulting from infrastructure construction.This paper divided the Ya’an-Qamdo transport section into 22subzones according to their ecological environment characteristics.Based on the vulnerability evaluation model established by the fuzzy matter-element analysis method,the eight main assessment indicators of ecological vulnerability were windstorm,rainstorm,snowstorm,extreme temperature,extreme air pressure,geological hazard,natural conditions,and social resources.The rating and ranking of vulnerability in each subzone were based on the weight of the judgment indicators.Scientific processes were used to verify the rationality of both the indicators themselves and their weights.The results of this study show that subzone 9,located in the subalpine cold and humid forest and scrubland zone,is the most vulnerable,and subzone 1,located in the low-to mid-land warm and humid forest zone,is the least vulnerable.The conclusion of the study suggests that targeted measures of ecological protection should be formulated before development and construction of major transportation infrastructure.Construction should evade the most vulnerable areas,and in-depth research on ecological restoration should be carried out in low-to midvulnerability areas so that the ecological environment along the route can be protected effectively for sustainable economic and social development.
基金supported in part by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)under Grant 2019QZKK0902the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant XDA23090203the National Natural Science Foundation of China under Grant 42071411。
文摘Accurate evaluation of landslide susceptibility is very important to ensure the safe operation of mountain highways.The Sichuan-Tibet Highway,which traverses the east of the Tibetan Plateau,frequently encounters natural hazards.Previous studies generally use statistical methods to analyze the hazards along the Sichuan-Tibet Highway.In this research,we present two road factors,namely aspect to road and road profile to increase the accuracy of landslide susceptibility mapping by considering the influence of landslide movement direction on road.First,the aspect to road,which represents the impact of different landslide movement directions on the highway,was extracted by combining road direction with mountain aspect.Then,the road profile,which reflects the subgrade structure between the road and surrounding mountains,was extracted according to the terrain data.Finally,the landslide susceptibility maps were produced based on the random forest(RF)method by using 473 landslides and 10 conditioning factors,including road factors(aspect to road,road profile)and primitive factors(slope,aspect,curvature,relief amplitude,peak ground acceleration,crustal movement velocity,faults,rainfall).The area under the receiver operating characteristic curve(AUC)and the Gini importance were used to evaluate the performance of proposed road factors.The AUC values on two groups that add road factors and only use primitive factors were 0.8517 and 0.8243,respectively.The Gini importance indicated that road profile(0.123)and aspect to road(0.116)have a significant contribution to landslides compared with the primitive factors.The results of multi-collinearity analysis and frequency ratio confirmed the suitability of the road factors for predicting hazards along the highway.
文摘SIXTY-EIGHT years ago, the Song of the Erlang Mountain was a smash hit all over China. It is an ode to the heroic builders of the highway between Sichuan and Tibet, which cuts through towering mountains and spans billowy rivers.
基金supported by the National Scientific Foundation of China[grant number 42161063]Open Foundation of Key Laboratory of Yellow River Water Environment in Gansu Province[grant number 121YRWEK001]+4 种基金Science and Technology Plan of Gansu Province[grant number 20JR2RA002]Natural Science Foundation of Gansu Province[grant number 20JR10RA249]Youth Science and Technology Foundation of Gansu Province[grant number 20JR10RA272]Lanzhou Jiaotong University-Tianjin University Innovation Project Fund Project[grant number 2020055]Jiayuguan City 2021 Science and Technology Plan Projects[grant number 21-35].
文摘The anomalous movements of glaciers cause disasters,such as debrisflows and landslides.It is very important to assess the glacier movements and their future trends.Glacier velocity refers to movement process.The current research aims to analyse past and current spatiotemporal changes in glacier velocity.No study has used neural network model to conduct a spatiotemporal prediction for glacier velocity.Therefore,this paper selected typical mountain glaciers G2 and G5 along the Sichuan-Tibet Railway as research objects and constructed the Convolutional Gate Recurrent Unit(ConvGRU)spatiotemporal prediction model based on 1988–2018 Landsat data to predict velocities in 2019–2028,and analysed the future trends of G2 and G5.The evaluation indexes met the model requirements to a large extent,quantitatively showing that the model has high accuracy and can successfully capture thefluctuation changes in time series data of glacier velocity.The mean deviations of G2 and G5 were 0.09 and-0.47 m/yr,respectively,reflecting the high reliability of the model applied to extraction of glacier velocity.The velocities of G2 and G5 showed a slow downtrend withfluctuations;that is,they will not cause damage to the construction and operation of the Sichuan-Tibet Railway in the short term.
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20020201)Breakthrough Project of Strategic Priority Program of Chinese Academy of Sciences(KFZD-SW-426)+2 种基金National Natural Science Foundation of China(41675094 and 41975115)Natural Science Foundation of Shaanxi Province(2021JQ-166)Open Research Fund of Key Laboratory of the Loess Plateau Soil Erosion and Water Process and Control,Ministry of Water Resources of China(HTGY202002)。
文摘Based on multiresource high-resolution in situ and satellite merged observations along with model simulations from the Coordinated Regional Climate Downscaling Experiment(CORDEX),this study first investigated historical changes in extreme temperature and precipitation during the period of 1979-2018 in areas along the Sichuan-Tibet Railway,and then projected the future changes in the frequency and intensity of extreme temperature and precipitation under the RCP(Representative Concentration Pathway)4.5 and 8.5 scenarios.This paper is expected to enhance our understanding of the spatiotemporal variability in the extreme temperature and precipitation along the Sichuan-Tibet Railway,and to provide scientific basis to advance the Sichuan-Tibet Railway construction and operation.The results show that temperatures in the Sichuan-Tibet region display a noticeable warming trend in the past 40 years,and the increase of minimum temperature is significantly higher than that of maximum temperature in the northwest of the region.Significant increase of precipitation is found mainly over the northwest of the Tibetan Plateau.Except for Lhasa and its surrounding areas,precipitation over other areas along the Sichuan-Tibet Railway shows no significant change in the past 40 years,as indicated in five datasets;however,precipitation along the railway has shown a remarkable decrease in the past 20 years in the TRMM satellite dataset.The warm days and nights have clearly increased by 6 and 5 day decade1-for 1979-2019,while cold days and nights have markedly decreased by about 6.6 and 3.6 day decade-1,respectively.In the past 20 years,the areas with increased precipitation from very wet days and extremely wet days are mainly distributed to the north of the Sichuan-Tibet Railway,while in the areas along the railway itself,the very wet days and extremely wet days are decreasing.Under RCPs 4.5 and 8.5,the temperature in the Sichuan-Tibet region will increase significantly,and the frequency of extreme high(low)temperature events in the late 21 st century(2070-2099)will greatly increase(decrease)by about 50%-80%(10%)compared with occurrences in the late 20 th century(1970-1999).Meanwhile,the frequency of very wet days and extremely wet days in the Sichuan-Tibet region will increase by about 2%-19% and 2%-5%,respectively,and the areas along the Sichuan-Tibet Railway will be affected by more extreme high temperature and extreme precipitation events.
基金This study was supported by the National Natural Science Foundation of China(Grant No.71942006)the Fundamental Research Funds for the Central Universities(2019RC053).
文摘Safety is one of the most critical themes in any large-scale railway construction project.Recognizing the importance of safety in railway engineering,practitioners and researchers have proposed various standards and procedures to ensure safety in construction activities.In this study,we first review four critical research areas of risk warning technologies and emergency response mechanisms in railway construction,namely,(i)risk identification methods of large-scale railway construction projects,(ii)risk management of large-scale railway construction,(iii)emergency response planning and management,and(iv)emergency response and rescue mechanisms.After reviewing the existing studies,we present four corresponding research areas and recommendations on the Sichuan-Tibet Railway construction.This study aims to inject new significant theoretical elements into the decision-making process and construction of this railway project in China.
基金supported by the National Natural Science Foundation of China(Nos.52078488 and 52078501)the Project of National Railway Administration of China(No.KF2019-018)the Science and Technology Research and Development Plan of China State Railway Group Co.,Ltd.(No.L2021G006)。
文摘Spatial and temporal temperature variations are critical for concrete box girders,and non-uniform temperature distributions induced by solar radiation depend on the structural shapes and shadows cast on them.There have been many studies of temperature distributions and temperature gradients of concrete box girders,but few have considered a high altitude plateau climatic environment.In this study,the nonlinear temperature distributions of concrete box girders in the Sichuan-Tibet railway caused by solar radiation were investigated based on experimental analysis,real-time shadow-selection algorithm,and finite element method.Furthermore,a vertical temperature gradient model of the concrete box girders was obtained.The vertical temperature gradient values first rise,then decrease,and finally rise again from Chengdu to Lhasa,with samples forming a normal distribution.The recommended vertical temperature gradient value was 25℃with a confidence interval of 95%.This provides a reference for the design and maintenance of concrete box girders on the Sichuan-Tibet railway.
基金This research is supported by the National Natural Science Foundation of China(Grant No.71942006)Chinese Academy of Engineering(Grant No.2O21-XBZD-2).
文摘The Sichuan-Tibet Railway is facing extraordinary challenges in terms of construction,operation,and maintenance because of its extremely complicated natural environment and geological conditions.Consequently,countermeasures are necessary and urgent to ensure its safety and reliability in the whole life cycle.This study proposes a novel reliability framework to guarantee the ideal operation state of the Sichuan-Tibet Railway.Reliability application in many fields are summarized,including military equipment,rail locomotive,and railway engineering.Given the fact that the Sichuan-Tibet Railway is a complex giant system,Nine-Connotation was summarized(i.e.,safety,inherent reliability,testability,maintainability,supportability,environmental adaptability,predictability,resilience,and durability)under the goal of optimizing the operational efficiency.On the basis of the concept of the Nine-Connotation and the understanding of reliability transmission mechanism,the framework of reliability for the Sichuan-Tibet Railway was established,which can facilitate a comprehensive and real-time evaluation of all situations with a clear hierarchy.The proposed framework is composed of a resilience management system,an integrated technology system,and a dynamic reliability assessment system.The pathway for its application on railway construction was developed in this study.The proposed framework can assist in well-informed decisions for the construction,as well as the operation of the Sichuan-Tibet Railway.On the basis of a top-down design concept for the first time,this study emphasizes the railway's availability and validity to complete the assigned tasks as a whole,that is,operational efficiency.It also shows the reliability transmission and control mechanism of the railway's giant complex system,innovating and establishing the management principle of great safety and great reliability over the life cycle.
