为探讨列车轴重和运行速度对土质路基动力特性的影响，用ANSYS与FLAC3D软件对有砟轨道-路基系统进行了三维动力数值模拟，在模拟过程中，利用滞后阻尼实现了土体在循环动荷载下的非线性特性。用该方法对达成线循环加载试验段的路基进行建模计算，所得路基动应力与现场实测数据有很好的一致性。在荷载振动频率与客车运行速度的转换过程中，取相邻车厢两个转向架的间距为相邻两个动应力波峰之间的距离，在此基础上，探讨了客车运行速度对土质路基动力性质的影响。研究表明：列车轴重和运行速度对路基表面动应力影响较大，随着轴重的增加和速度的提高，路基表面动应力呈马鞍形分布的趋势愈加明显；动应力沿路基深度的衰减规律受车速的影响很小，不同车速下的动应力在基床表层内都衰减了42％～46％，再经过基床底层的扩散，衰减值达79％～82％。%To discuss the effect of train axle load and speed on the dynamic characteristics of soil subgrade,a 3D dynamic simulation of the ballast track-subgrade system was made using ANSYS and FLAC3D. In the calculation process,the hysteretic damping was used to simulate the nonlinear characteristics of soil under cyclic dynamic loading. The proposed method was then used to calculate the dynamic stress of subgrade in the field cyclic loading test of the Dazhou-Chendu railway,and the simulation results showed a good agreement with the field measurements. In the conversion between the load vibration frequency and the passenger train speed,the distance between the peaks of the adjacent dynamic stress was simplified as the two bogie spacing of adjacent compartments. On this basis,the effect of passenger train speed on the dynamic property of soil subgrade was investigated. The results indicate that train axle load and speed has a large impact on the dynamic stress of subgrade surface. With an increase in axle load and speed,the saddle-shaped distribution of dynamic stress of subgrade surface is more obvious. However,train speed has little effect on the attenuation law of dynamic stress along the subgrade depth. The dynamic stress is attenuated by 42% 46% in the subgrade surface layer,and the attenuation value can reach 79% 82% after the diffusion of subgrade bottom layer at different speeds.
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