地铁车辆段上盖建筑道砟垫减振机理与效果

为了分析道砟垫对上盖建筑的减振效果,对杭州市某地铁车辆段咽喉区、试车线碎石道床(含道砟垫)轨道和上盖建筑振动响应进行现场测试.考虑桩与土体的相互作用,建立列车-轨道-土体-桩-上盖建筑三维全耦合动力学模型,揭示了车辆段列车引起上盖建筑振动传播的规律以及道砟垫对上盖建筑减振的机理,分析不同车速下道砟垫刚度对减振效果的影响.结果发现,上盖建筑底层振动主频为40～80 Hz,高频成分随着层高衰减明显;建筑顶层振动主频为20～40 Hz,低频成分随着层高有增大的趋势.道砟垫对上盖建筑的减振效果随着频率的增大呈整体改善的趋势,40 Hz以上的频段,结构最大插入损失可达7～12 dB.车速越高,道砟垫刚度越小,道砟垫对上盖建筑的减振效果越好.综合考虑道砟垫压缩量和减振效果,建议道砟垫刚度取值为0.012～0.024 N/mm³.

Vibration mitigation mechanism and effect of ballast mats for over-track buildings on metro depot

The vibration responses of track structures in the throat area and test line (with ballast mats) and those of over-track buildings at Hangzhou metro depot were tested in order to analyze the vibration mitigation effect of ballast mats on over-track buildings. A three-dimensional fully-coupled dynamic model of train-track-soil-pile-building was established by considering the interaction between pile and soil. The model revealed the vibration propagation laws of over-track buildings caused by train in the metro deport and the mitigation mechanism of ballast mats on over-track buildings. The influence of stiffness of ballast mats on vibration mitigation effect under different train speeds was analyzed. Results showed that the main frequency range of ground floor vibration was 40-80 Hz, and the high frequency component obviously attenuated with story height. The main frequency range of the vibration of the top floor of the building was 20-40 Hz, and the low frequency component tended to increase with the height of the building. Ballast mats had a good vibration mitigation effect on the over-track building with the increase of frequency. The maximum insertion loss of structures reached 7-12 dB in the frequency band above 40 Hz. The higher speed of the train, the smaller stiffness of ballast mats, the better the vibration mitigation effect of the ballast mats on over-track buildings would be. Compression deformation and vibration mitigation effect were considered. It was recommended that the stiffness range of ballast mats was 0.012-0.024 N/mm³.