高速列车荷载作用下无砟轨道扣件系统动力分析

DYNAMIC RESPONSE OF FASTENING SYSTEM FOR BALLASTLESS TRACK DUE TO HIGH-SPEED TRAIN LOADS

  • 摘要: 为探究移动高速列车荷载引起的无砟轨道扣件系统的受力性态,借助有限元方法,基于精细化建模技术,考虑扣件各部件实际尺寸、轨底坡影响和材料超弹性行为,构建精细化的轨道结构-路基-地基非线性动力学仿真模型。以地基中土体的初始应力场为基础,得到列车荷载作用前的静应力状态。以高精度的三维黏弹性静-动力统一人工边界描述地基无限域,基于动力相互作用理论模拟各部件间的动接触行为。采用实测的高速列车荷载为输入激励,运用移动荷载模拟方法实现列车荷载的高速移动以模拟列车运行。所开发模型的正确性和合理性已被高速铁路路基不同部位不同指标同时验证,采用该模型研究了列车荷载高速移动下扣件系统中主要部件的动力学响应。结果发现,受轨底坡影响,钢轨底面Mises动应力分布明显偏于钢轨内侧,弹条的动应力响应在路基横断面平面内最为剧烈,弹条上结点三个方向的作用力大小相当。Mises动应力在承轨台顶面呈中间大而两端小的马鞍形分布。所考察时刻钢轨内侧和外侧锚固螺栓底面的动应力随与钢轨距离的接近先减小后增大,最大值分别为2.56 MPa和7.14 MPa。绝缘缓冲垫板底面的Mises动应力高度不均匀,呈现局部回弹和压缩状态,数值处于Pa级。钢轨底面以下五层结构的Mises动应力大小取决于不同部件之间相对刚度的大小,在刚度差异显著的界面发生1000倍以上的突变,而在同一层结构的底面和顶面基本不变。基于研究结果,揭示了列车荷载在实体扣件系统中的传递机制。

     

    Abstract: In order to investigate the stress behavior of fastening system for ballastless track caused by high-speed train load, an elaborated nonlinearly dynamic finite element model for track-subgrade-foundation system was developed based on elaborate modelling method. In this model the actual shape and dimension of fastening system was sufficiently considered. The influence of rail cant and hyper elastic behavior of rubber material were taken into account. The initial stress condition in foundation was generated and was treated as the starting state for solving the static stress state in track-subgrade-foundation prior to the movement of train load. The verified three dimensional viscoelastic static-dynamic unified artificial boundary with high precision was introduced to represent infinite domain, and the dynamic contact behavior between different parts of the overall model was simulated based on interaction theory. The input excitation was acquired in field measurement, and the running of train was modelled as moving load at high speed. The correctness of the developed model was simultaneously validated by different indices obtained from different locations of subgrade in high-speed rail. The stress states of main components in the fastening system under high speed movement of train load were investigated in detail. The results show that the Mises dynamic stress distribution at the bottom of rail is significantly nonuniform than that at the inner side due to the influence of rail cant, and the dynamic stress response of the spring bar is the most severe at the cross-sectional direction of the subgrade, and the clamping forces of fastener are at the same magnitude in three directions. Mises dynamic stress is distributed on the top surface of the sleeper in saddle shape, with a large middle and small ends. The dynamic stresses on the bottom surface of the inner and outer anchoring bolts of the rail firstly decrease and then increase with the decrease of the distance from the rail, and the maximum values are 2.56 MPa and 7.14 MPa, respectively. The Mises dynamic stress at the bottom of the insulating and buffering rubber pad is highly non-uniform, showing local spring back and compression, and the value of stress is in the magnitude of Pa. For the five-layer structure below the bottom surface of the rail, Mises dynamic stress is determined by the relative stiffness of different components. The Mises dynamic stress has a sudden change of over 1000 times at the interface with significant stiffness differences, while the Mises dynamic stress remains almost the same at the bottom and top surface of the same layer. The transfer mechanism of train load through solid fastening system has been revealed.

     

/

返回文章
返回