周期性钢弹簧浮置板轨道垂向振动带隙特性研究

Study on Vertical Vibration Band Gap Properties of Periodic Steel Spring Floating Slab Track

为研究周期性钢弹簧浮置板轨道的带隙特性,将钢轨和浮置板分别视为铁木辛柯梁和明德林板,建立周期性钢弹簧浮置板轨道垂向振动模型,基于能量变分原理求得其垂向带隙,分析带隙的形成机理以及轨道结构刚度对带隙的影响。结果表明:在0~1200 Hz范围内,周期性钢弹簧浮置板轨道结构存在5条垂向振动带隙,1阶和3阶带隙为局域共振带隙,2阶和4阶带隙由轨道结构的弹性运动所引起,5阶为布拉格带隙;在1阶带隙内弹性波直接传入下部基础中,且带隙宽度随钢弹簧刚度增大而增大;在2~4阶带隙内弹性波被限制在激振点附近的浮置板内,带隙频率位置和宽度主要受扣件刚度影响;在5阶带隙内弹性波因布拉格散射而被耗散,带隙宽度随扣件刚度增大而增大。针对1阶、2~4阶以及其他频率段的弹性波,可分别采用减隔振基础、浮置板吸振器和钢轨吸振器进行轨道结构的精细化减振。

In order to research the band gap properties of periodic steel spring floating slab track,the vertical vibration model of periodic steel spring floating slab track was established by taking the rail and floating slab as Timoshenko beam and Mindlin slab respectively.The vertical band gap was obtained based on the energy variation principle.The formation mechanism of band gap and the influence of the track structure stiffness on band gap were analyzed.The results show that in the range of 0-1200 Hz,there are five vertical vibration band gaps in the periodic steel spring floating slab track structure.The 1 st-order and 3 rd-order band gaps are locally resonant band gaps,the 2 nd-order and 4 th-order band gaps are caused by the elastic motion of the track structure,and the 5 th-order band gap is Bragg band gap.The elastic waves in the 1 st-order band gap are directly transmitted into the lower foundation and the width of band gap increases with the increase of steel spring stiffness.The elastic waves in the 2 nd-order to 4 th-order band gaps are confined to the floating slab near the excitation point and the frequency position and width of band gaps are mainly affected by the fastener stiffness.The elastic waves in the 5 th-order band gap are dissipated due to Bragg scattering and the width of band gap increases with the increase of fastener stiffness.For elastic waves in the 1 st,2 nd to 4 th-order and other frequency bands,the foundation of vibration isolation,the vibration absorber of floating slab and rail can be used to refine the vibration reduction of track structure.