地铁列车运行引起的振动对精密仪器影响的预测研究

采用一种动力有限元数值模型，并结合道路交通现场振动测试，对北京地铁8号线列车运行对邻近地铁线路的某科研楼内精密仪器的振动影响进行了预测研究，并比较了普通无砟轨道和浮置板轨道两种工况下楼内外的振动响应。提出了该有限元模型的网格划分、边界条件、阻尼施加等建模原则，采用实测的钢轨振动加速度计算而来的动态轮轨力作为该模型上的激励力。结果表明：采用该动力有限元模型可以有效地预测地铁列车运行引起的振动；浮置板轨道是一种有效的减振措施，在其工作频段内有显著的减振效果，但对低频振动没有减振效果，而且在其自振频率处还有一定的放大作用；地铁8号线开通后，地铁列车振动再叠加上道路交通引起的振动会对科研楼内部分精密仪器的正常工作造成一定的影响，仪器基座处可采取相应的隔振措施来减小这部分振动。

PREDICTION OF EFFECT ON SENSITIVE INSTRUMENTS DUE TO VIBRATIONS INDUCED BY RUNNING METRO TRAINS

The effect on the sensitive instruments in a building near metro line 8 in Beijing due to vibrations induced by metro traffic was predicted by means of a dynamic finite element model and in-situ measurement of road traffic induced vibrations, and responses inside and outside the building for the case of general non-ballast track and floating slab track in the tunnels were compared. In this paper, the mesh generation, the boundary condition and the damping in the finite element model were presented, the calculated dynamic wheel-rail force based on the in-situ vibration measurement on the rails are applied on the model. The results show that the vibrations induced by passage of metro trains in the tunnels can be effectively predicted using the dynamic finite element model. The floating slab track is an effective vibration mitigation measure, which can efficiently reduce the vibrations in its work frequency range. However, the floating slab track cannot reduce the vibrations at low frequencies, and increases the response at its resonance frequency. The combined vibrations due to road traffic and metro traffic will affect a few sensitive instruments after the metro line 8 is operated, which can be reduced by the passive isolation measure under the base of equipment.