Zeng Zhiping, Xiao Yancai, Wang Weidong, Huang Zhibin, Wei Wei, Houdou Saidi Boumedienne
School of Civil Engineering, Central South University, Changsha 410075, China.
MOE Key Laboratory of Engineering Structures of Heavy Haul Railway, Central South University, Changsha 410075, China.
Materials (Basel). 2022 Mar 10;15(6):2033. doi: 10.3390/ma15062033.
To fill the blank in the research on the dynamic performance of track structure under long-term service, the dynamic response study of China Railway Track System Ⅲ type slab ballastless track (CRTSIII SBT) under the action of fatigue for 30 million times and the parting between track slab and self-compacting concrete (SCC) was carried out. By establishing the finite element model of the CRTSIII SBT structure and taking the stiffness change of isolation layer and fastener under fatigue state and the parting during service as the research objects, combined with the full-scale model test, the dynamic response amplitude and vibration law of track structure was analyzed based on the finite element model of axle falling test method. The results show the following: (1) Under the fatigue load, the acceleration of rail and base increases obviously, the longitudinal tensile stress of SCC surface decreases, the longitudinal tensile stress of base surface increases, and the vertical stress of each layer of track structure increases as well. (2) Under the action of the parting, the dynamic response of each structural layer increases, and the change of acceleration and stress of each layer under the action point of axle falling is the most obvious. (3) The fatigue load will weaken the vibration damping performance of the track, and the parting will continue to develop under the action of the falling axle, resulting in partial or total failure of the SCC layer. Both of them will aggravate the dynamic response of the track structure and affect driving safety, which should be paid attention to during maintenance.
为填补长期服役下轨道结构动态性能研究的空白，开展了中国铁路轨道系统Ⅲ型板式无砟轨道（CRTSIII SBT）在3000万次疲劳作用及轨道板与自密实混凝土（SCC）脱开情况下的动态响应研究。通过建立CRTSIII SBT结构的有限元模型，以疲劳状态下隔离层和扣件的刚度变化以及服役期间的脱开为研究对象，结合足尺模型试验，基于落轴试验方法的有限元模型分析了轨道结构的动态响应幅值及振动规律。结果表明：（1）在疲劳荷载作用下，钢轨和底座的加速度明显增大，SCC表面纵向拉应力减小，底座表面纵向拉应力增大，轨道结构各层竖向应力也增大。（2）在脱开作用下，各结构层的动态响应增大，落轴作用点下各层加速度和应力的变化最为明显。（3）疲劳荷载会削弱轨道的减振性能，脱开在落轴作用下会继续发展，导致SCC层局部或全部破坏。二者都会加剧轨道结构的动态响应并影响行车安全，在养护维修时应予以重视。
