中文摘要：

视轨道结构为轨枕（或扣件）周期支撑的无限长周期结构，利用匀速移动谐振荷载作用下周期结构在频域内响应的性质和叠加原理，将求解匀速移动荷载作用下轨道结构振动响应问题的关键转化到在频域内解1个8元一次方程组。运用给出的解析方法对移动荷载作用下轨道结构的振动研究表明：在中低速单个移动谐振荷载作用下，钢轨位移频谱的峰值出现在荷载频率附近，且随着荷载速度的增加，频谱峰值变小，峰值位置向轨道固有频率靠近；力群的叠加使钢轨位移的频谱分布加宽；随着移动速度的增加，列车轴荷载下钢轨的位移频谱向高频移动；轨道结构有多个临界速度，提高基础的刚度，可以提高轨道的最小临界速度；基础阻尼能明显减缓轨道结构的强振动。

英文摘要：

The track structure is regarded as an infinite periodic structure which is periodically supported by sleepers （or fasteners）. Using the characteristics of the periodic structure＇s dynamic response in fre- quency domain under a harmonic moving load with a constant velocity and the principle of superposition, the key point of solving the track vibration under moving loads is transformed to solve a system of linear e- quations with eight unknowns in frequency domain. From the researches on the track vibration under mov- ing loads which are based on the proposed analytical method, the following conclusions are obtained, under a single harmonic moving load with middle-low velocity, the peak location of rail displacement spectrum appears near the load frequency, and with the increase of load velocity, the peak of rail displacement spec- trum becomes smaller~ while the peak location moves towards the natural frequency of track. Due to the superposition of series of loads, the rail displacement spectrum would have a broader distribution. With the increase of moving velocity, the rail displacement spectrum under train axle-load would move towards higher frequencies. There are several critical velocities in the track structure, and the minimum one can be increased through improving foundation stiffness. The presence of foundation damping can significantly re- duce the vibration boom of track structure.