The geometry of a ballasted railway gradually deteriorates with trafficking, mainly as a result of the plastic settlement of the track-bed (ballast and sub-base). The rate and amount of settlement depend on a number of factors, and for various reasons are difficult to predict or estimate analytically. As a result, various empirical equations for estimating the rate of development of plastic settlement of railway track with train passage have been proposed. A review of these equations shows that they (i) do not reproduce the form of settlement vs number of load cycles relationships usually seen in the field; (ii) do not reflect current knowledge of the behaviour of soil subgrades in cyclic loading; and (iii) are often critically dependent on the curve fitting parameters used, which in turn depend on the circumstances in which the calibration data were obtained. To address these shortcomings, this paper develops a semi-analytical approach, based on the known behaviour of granular materials under cyclic loading, for the calculation of plastic settlements of the trackbed with train passage. The semi-analytical model is then combined with a suitable vehicle-track interaction analysis to calculate rates of development of permanent settlement for different initial trackbed stiffnesses, vehicle types and speeds. The model is shown to be able to reproduce recursive effects, in which a deterioration in track geometry causes an increased variation in dynamic load, which feeds back into a further deterioration in track geometry. The new model represents a significant improvement on current empirical equations, in that it is able to reproduce observed aspects of railway track settlement on the basis of the known behaviour of soils and ballast in cyclic loading.

压载铁路的几何形状随着运输的增长而逐渐恶化，这主要是由于道床（压载物和底层）的塑性沉降所致。结算的速度和金额取决于许多因素，由于各种原因，很难通过分析来预测或估计。结果，提出了各种经验方程式，以估计具有火车通过的铁路轨道塑性沉降的发展速度。这些公式显示了审查，他们（我）不会重现结算的形式VS通常在现场看到的负载循环关系数；（ii）没有反映当前对循环荷载作用下土基行为的认识；（iii）通常严格取决于所使用的曲线拟合参数，而曲线拟合参数又取决于获得校准数据的环境。为了解决这些缺点，本文基于颗粒材料在循环载荷下的已知行为，开发了一种半分析方法，用于计算带火车通道的路基的塑性沉降。然后将半分析模型与合适的车辆-轨道相互作用分析相结合，以计算不同初始轨道床刚度，车辆类型和速度的永久沉降的发展速度。该模型显示出能够再现递归效果，其中，轨道几何形状的恶化会引起动载荷变化的增加，这会反馈到轨道几何形状的进一步恶化。新模型代表了当前经验公式的重大改进，因为它能够基于已知的土壤和压载在循环荷载下的行为，重现观察到的铁路轨道沉降情况。