提速列车荷载作用下铁路路基动力特性的研究

结合铁路提速现状，分析了既有线上运行最高时速200 km/h客车、120 km/h货车时路基的动力响应。首先，采用列车-轨道耦合动力学模型，计算轮轨间相互作用力，然后，通过非线性数值分析，研究不同列车编组和行车速度条件下路基的动力响应，包括路基横断面的动应力、位移和加速度的大小、分布规律、沿路基深度内的衰减，并探讨了路基参数与动力响应的关系，同时与既有线的部分实测结果进行对比分析。研究表明，列车速度提高对路基动力响应的影响有限，但轴重的影响很大；对既有线路基加固时，存在一个最佳的路基刚度值（120 MPa）；道床厚度增加，路基动应力线性减少，但路基动位移和加速度变化不明显。

Dynamic responses of existing-railway subgrade with train speed increasing

Considering the increase of speed-trains in existing railways of China, i.e., passenger train will run at speed of 200 km/h and heavy truck at speed of 120 km/h, thus the dynamic responses of railway subgrade with train speed increasing are studied. Firstly, the coupled dynamic model of train-track-subgrade is applied to calculate the interaction force between wheel and track. Subsequently, according to nonlinear numerical analysis, the dynamic responses of subgrade are analyzed with different train groupages and running speeds, including the dynamic subgrade stress, displacement and acceleration, and their distribution and attenuation in subgrade. Moreover, relationships between the design parameters of subgrade and its dynamic responses are also studied. Field measured data were used to verify the numerical results. It is found that the influence of train speed on subgrade dynamic responses is limited, whereas the axial load of train affects subgrade greatly; there is an optimum stiffness for strengthened subgrade(i.e. 120 MPa). With the thickness of ballast increasing, the subgrade dynamic stress reduces linearly, but dynamic displacement and acceleration have a negligible change.