基于欧标的埋入式无砟轨枕结构设计方法研究
|
摘要
研究目的:欧洲标准是国际铁路市场采用的主要铁路设计标准之一,掌握欧洲标准的设计理论和计算方法是实施海外铁路项目的必要条件。本文以1 676 mm宽轨距埋入式无砟轨枕为例,研究基于欧洲标准的无砟轨枕设计方法,推导轨枕荷载弯矩、混凝土预应力损失的计算过程,分析轨枕结构承载能力及静载、动载和疲劳试验荷载计算方法,通过设计案例再现采用欧洲标准指导宽轨距无砟轨枕设计方法。研究结论:(1)欧洲标准就枕上垂直动压力考虑因素较多,以扣件弹性衰减系数、速度系数、纵向荷载分配系数和支承缺陷引起的纵向荷载分配影响系数在计算公式中体现;(2)轨枕混凝土预应力损失包括锚具变形引起的预应力损失、放张前预应力钢筋松弛损失、钢筋放张时混凝土弹性变形产生的损失和时变损失,时变损失的计算方法反映了环境条件、轨枕尺寸、混凝土品类和加载龄期对时变损失的影响;(3)轨枕混凝土承载能力检算应考虑施工荷载引起的枕中截面正弯矩和轨下截面负弯矩;(4)本研究成果可应用于海外铁路轨道工程设计。
Research purposes: The European standard is one of the main railway design standards adopted in the international railway projects. To master the design theory and calculation method of European standards is a necessary condition for overseas railway projects. In this paper,the 1 676 mm broad-gauge embedded sleeper for ballastless track was taken as an example to research the design method of the ballastless sleeper based on European standards. The calculation process of the load bending moment and the prestress loss of the concrete sleeper were derived. The calculation methods for the bearing capacity of sleeper structure and the test load for the static,dynamic and fatigue test were analyzed. A design case was given to illustrate the design of the broad-gauge ballastless sleeper using the European standard.Research conclusions:( 1) According to the European standard,there are more factors considered for the vertical dynamic pressure above the sleeper. The factors are reflected in the calculation formula including the factor to allow for rail pad attenuation,the factor to allow for the effect of speed,the factor used for longitudinal load distribution between sleepers and the factor used for variations of the longitudinal load distribution between sleepers due to support faults.( 2) The prestress loss of the sleeper concrete includes the ones caused by the anchorage deformation,the relaxation of the prestressed steel bar before tensioning,the elastic deformation of concrete while tensioning and the time dependent loss. The calculation method for the time dependent loss reflects the influence of environment condition,sleeper dimension,concrete type and concrete age of loading.( 3) The positive bending moment at the center section and the negative bending moment at the rail seat section caused by the construction load are taken into account for the check on the bearing capacity of the sleeper concrete.( 4) The research achievements can be used to guide the overseas railway track engineering design.
Research purposes: The European standard is one of the main railway design standards adopted in the international railway projects. To master the design theory and calculation method of European standards is a necessary condition for overseas railway projects. In this paper,the 1 676 mm broad-gauge embedded sleeper for ballastless track was taken as an example to research the design method of the ballastless sleeper based on European standards. The calculation process of the load bending moment and the prestress loss of the concrete sleeper were derived. The calculation methods for the bearing capacity of sleeper structure and the test load for the static,dynamic and fatigue test were analyzed. A design case was given to illustrate the design of the broad-gauge ballastless sleeper using the European standard.Research conclusions:( 1) According to the European standard,there are more factors considered for the vertical dynamic pressure above the sleeper. The factors are reflected in the calculation formula including the factor to allow for rail pad attenuation,the factor to allow for the effect of speed,the factor used for longitudinal load distribution between sleepers and the factor used for variations of the longitudinal load distribution between sleepers due to support faults.( 2) The prestress loss of the sleeper concrete includes the ones caused by the anchorage deformation,the relaxation of the prestressed steel bar before tensioning,the elastic deformation of concrete while tensioning and the time dependent loss. The calculation method for the time dependent loss reflects the influence of environment condition,sleeper dimension,concrete type and concrete age of loading.( 3) The positive bending moment at the center section and the negative bending moment at the rail seat section caused by the construction load are taken into account for the check on the bearing capacity of the sleeper concrete.( 4) The research achievements can be used to guide the overseas railway track engineering design.
引文
[1]刘辉.中外铁路工程建设标准对比及海外应用探讨[J].铁道工程学报,2017(9):1-8.Liu Hui. Exploration on the Comparison and Overseasproject Application of Railway Engineering Construction Standard in China and Foreign Countries[J]. Journal of Railway Engineering Society,2017(9):1-8.
[2]田春香.基于美标的铁路宽轨距轨枕结构设计与计算[J].铁道工程学报,2015(2):60-63.Tian Chunxiang. Structure Design and Calculation of Broad Gauge Sleepers Based on American Code[J].Journal of Railway Engineering Society,2015(2):60-63.
[3]林红松,颜华. 30 t轴重重载铁路混凝土轨枕设计与试验研究[J].高速铁路技术,2016(3):69-72.Lin Hongsong, Yan Hua. Research on Design and Experiment of Concrete Sleeper Suitable for 30 t Axle Load Heavy Haul Railway[J]. High Speed Railway Technology,2016(3):69-72.
[4]任树文,龚昕.南京地铁机场线预应力混凝土长轨枕结构设计[J].铁道标准设计,2014(2):30-32.Ren Shuwen, Gong Xin. Structure Design of Prestressed-concrete Long Sleepers Used in Airport Line of Nanjing Metro[J]. Railway Standard Design,2014(2):30-32.
[5] pr EN 13230-6:2014(E),Railway Applications-TrackConcrete Sleepers and Bearers-Part 6:Design[S].
[6] BS EN1992-1-1 Eurocode 2:Design of Concrete Structures[S].
[2]田春香.基于美标的铁路宽轨距轨枕结构设计与计算[J].铁道工程学报,2015(2):60-63.Tian Chunxiang. Structure Design and Calculation of Broad Gauge Sleepers Based on American Code[J].Journal of Railway Engineering Society,2015(2):60-63.
[3]林红松,颜华. 30 t轴重重载铁路混凝土轨枕设计与试验研究[J].高速铁路技术,2016(3):69-72.Lin Hongsong, Yan Hua. Research on Design and Experiment of Concrete Sleeper Suitable for 30 t Axle Load Heavy Haul Railway[J]. High Speed Railway Technology,2016(3):69-72.
[4]任树文,龚昕.南京地铁机场线预应力混凝土长轨枕结构设计[J].铁道标准设计,2014(2):30-32.Ren Shuwen, Gong Xin. Structure Design of Prestressed-concrete Long Sleepers Used in Airport Line of Nanjing Metro[J]. Railway Standard Design,2014(2):30-32.
[5] pr EN 13230-6:2014(E),Railway Applications-TrackConcrete Sleepers and Bearers-Part 6:Design[S].
[6] BS EN1992-1-1 Eurocode 2:Design of Concrete Structures[S].