Evaluating railway track support stiffness from trackside measurements in the absence of wheel load data

It is generally accepted that track support stiffness is a major factor controlling rates of track geometry deterioration, particularly where the track support stiffness changes abruptly. There is, therefore, considerable potential benefit in being able to quantify and detect changes in the track support stiffness. In recent years, trackside techniques using various types of transducer have been developed to determine track deflections as trains pass. However, deducing the track support stiffness from these measurements requires assumptions to be made concerning train loading and track behaviour, and scope for different interpretations remains. For example, loads from moving trains vary dynamically and it is not usually feasible to measure their exact values at any given point along the track. This paper presents new methods of analysis, which can be applied to frequency spectra of track displacement, velocity or acceleration generated as trains pass to calculate the track support stiffness for trains of known axle intervals, without needing to know the actual loads applied. The approach is demonstrated with reference to theory and measured data from a range of field sites.

学界普遍认为，轨道支承刚度（track support stiffness）是控制轨道几何形位劣化速率的核心影响因素，在轨道支承刚度发生突变的工况下尤为显著。因此，能够量化并检测轨道支承刚度的变化，具备极高的应用潜力与实际价值。近年来，研究人员已开发出多种采用各类传感器（transducer）的轨旁检测技术，用于获取列车通过时的轨道挠度数据。然而，依托这类测量结果推导轨道支承刚度时，需预先针对列车荷载与轨道力学特性作出若干假设，因此仍存在多种解读的可能性。例如，运行列车的荷载处于动态变化状态，通常难以在轨道沿线的任意测点精准获取其实际荷载数值。本文提出了全新的分析方法，可基于列车通过轨道时产生的轨道位移、速度或加速度频谱，在无需知晓实际施加荷载的前提下，针对轴间距已知的列车计算轨道支承刚度。该方法通过理论推导与多现场测点的实测数据进行了验证与演示。