弯曲振动是浮置式轨道的主要振动模态.细致分析弯曲振动模态下浮置式轨道的振动放大效应,对优化轨道隔振设计有重要意义.本文基于有限元理论建立浮置式轨道动力分析模型,采用谐响应法,分析谐振荷载作用下轨道系统在频域内的结构响应,并以隔振效率为评价指标,定量分析弯曲振动模态下浮置式轨道的振动放大效应;探讨轨道结构参数的影响规律,推导一阶弯曲振动固有频率的简化计算公式.结果表明:浮置式轨道在弯曲振动模态下的振动有不同程度放大,一阶弯曲振动模态下的放大较明显,在本文参数条件下振动可放大1.69倍;增大板厚、减小板长及减小板下刚度,可明显减小振动放大效应;板厚大于0.55 m或板长小于3.6 m时,可不考虑轨道弯曲振动导致的振动放大效应.%Bending vibration is the main vibration mode of floating slab track (FST).The analysis of FST vibration magnification effect under the bending vibration mode is very important for the optimization of vibration isolation design of the track.A dynamic analysis model of FST was established based on the finite element method.The harmonic response method was used to analyze the structural response of FST in the frequency domain under harmonic load.With the vibration isolation efficiency as the evaluation index, the vibration magnification effect of FST under the bending vibration mode was quantitatively analyzed.The influences of the track parameters on the track vibration magnification effect were investigated.A simplified calculation formula of the natural frequency of the first order bending vibration was presented.The results show that the vibration transmitted to base is enlarged when FST is under the bending vibration mode.Especially, the vibration magnification under the first order mode of bending vibration is more obvious, with the vibration being amplified 1.69 times on the condition of given parameters.The increase of the slab thickness, decrease of the slab length or decrease of the stiffness of rubber pad under the slab can greatly reduce vibration magnification effect.When the slab thickness is thicker than 0.55 m or slab length is shorter than 3.6 m, the vibration magnification effect under the bending vibration mode can be ignored.
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