400 km/h高速铁路基床结构研究

Study on Subgrade Bed Structure of 400 km/h High-speed Railway

列车运行速度提高至400 km/h时,列车与线路相互作用更为复杂,路基承受的列车动力荷载作用更加剧烈。本文结合车辆-轨道-路基耦合动力学仿真,基于强度、变形和应变准则,对400 km/h高速铁路基床结构的设计方法进行了探讨,并对传统无砟轨道基床结构、全断面沥青混凝土强化表层基床及底层改良土基床结构在速度400 km/h条件下的适应性和设计参数进行了研究。研究表明:(1)400 km/h高速铁路基床结构应同时满足强度、变形及应变控制准则;(2)在轨道不平顺条件不变的条件下,随着列车运行速度的提高,路基面动力系数显著增加,且增加幅度逐渐增大;(3)速度400 km/h条件下,用于强度验算的路基面极限动力系数可取2.146,用于动变形和动应变计算的常遇动力系数可取1.491;(4)速度400 km/h条件下,传统无砟轨道基床底层地基系数K 30需要提高到150 MPa/m;(5)沥青混凝土起到了分散荷载的作用,在速度400 km/h条件下,全断面沥青混凝土强化表层基床结构底层的地基系数不低于145 MP/m即可满足要求;(6)压实性能达到要求时,改良土基床结构也可满足400 km/h速度要求。

When the train operation speed is increased to 400km/h,the track-train interaction will become more complex,and the subgrade will bear more severe dynamic load effect of the trains.In this paper,applying the vehicle-track-subgrade coupling dynamics simulation and based on the strength,deformation and strain criteria,the design method for the subgrade bed structure of 400 km/h high-speed railway is discussed,and the adaptability and design parameters under the conditions of 400 km/h are studied,regarding the subgrade bed structure of the traditional ballastless track,the subgrade bed with full-section asphalt concrete reinforced surface and the subgrade bed structure with improved soil at the bottom-layer.The study shows that:(1)The subgrade bed structure of 400 km/h high-speed railway shall meet the strength,deformation and strain control criteria.(2)Under the condition of constant track irregularity,the dynamic coefficient of subgrade surface increases significantly with the improvement of train operation speed,and the increase amplitude becomes larger gradually.(3)Under the conditions of 400 km/h,the ultimate dynamic coefficient of subgrade surface used for strength checking may be taken as 2.146,and the common dynamic coefficient used for dynamic deformation and dynamic strain calculation may be taken as 1.491.(4)Under the condition of 400 km/h,the subgrade coefficient K 30 of the bottom layer of the subgrade bed of the traditional ballastless track needs to be increased to 150 MPa/m.(5)Asphalt concrete plays the role of load distribution.Under the conditions of 400 km/h,the subgrade coefficient of the bottom layer of the subgrade bed structure with the full-section asphalt concrete reinforced surface greater than or equal to 145 MP/m can meet the requirements.(6)When the compaction performance meets the requirements,the subgrade bed structure of improved soil can also meet the requirements at 400 km/h.