Xu Qingyuan, Sun Shengwei, Xu Yi, Hu Changlin, Chen Wei, Xu Lei
Department of Civil Engineering, Central South University, Changsha, 410075, China.
Sci Rep. 2022 Aug 27;12(1):14638. doi: 10.1038/s41598-022-18898-y.
Temperature is an important load for ballastless track. However, there is little research on the system dynamic responses when a train travels on a ballastless track under the temperature gradient of ballastless track. Considering the moving train, temperature gradient of slab track, gravity of slab track, and the contact nonlinearity between interfaces of slab track, a dynamic model for a high-speed train runs along the CRTS III slab track on subgrade is developed by a nonlinear coupled way in ANSYS. The system dynamic responses under the temperature gradient of slab track with different amplitudes are theoretically investigated with the model. The results show that: (1) The proportions of the initial force and stress caused by the temperature gradient of slab track are different for different calculation items. The initial fastener tension force and positive slab bending stress have large proportions exceeding 50%. (2) The maximum dynamic responses for slab track are not uniform along the track. The maximum slab bending stress, slab acceleration, concrete base acceleration appear in the slab middle, at the slab end, and at the concrete base end, respectively. (3) The maximum accelerations of track components appear when the fifth or sixth wheel passes the measuring point, and at least two cars should be used. (4) The temperature gradient of slab track has a small influence on the car body acceleration. However, the influences on the slab acceleration, concrete base acceleration, fastener tension force are large, and the influence on the slab bending stress is huge.
温度是无砟轨道的重要荷载。然而，关于列车在无砟轨道温度梯度作用下行驶时系统的动态响应研究较少。考虑移动列车、板式轨道温度梯度、板式轨道自重以及板式轨道各界面间的接触非线性，在ANSYS中采用非线性耦合方法建立了高速列车在路基上沿CRTS III型板式轨道运行的动力学模型。利用该模型从理论上研究了不同幅值板式轨道温度梯度作用下的系统动态响应。结果表明：(1) 对于不同计算项目，板式轨道温度梯度引起的初内力和初应力所占比例不同。扣件初拉力和板式轨道正弯矩应力所占比例较大，超过50%。(2) 板式轨道的最大动态响应沿轨道分布不均匀。最大板式轨道弯矩、板式轨道加速度、混凝土底座加速度分别出现在板式轨道中部、板式轨道端部和混凝土底座端部。(3) 轨道部件的最大加速度出现在第5或第6个车轮通过测点时，且至少应使用两节车厢。(4) 板式轨道温度梯度对车体加速度影响较小。然而，对板式轨道加速度、混凝土底座加速度、扣件拉力影响较大，对板式轨道弯矩影响巨大。
