地铁列车运行引起的振动对精密仪器的影响研究

Study of effect on sensitive equipment due to vibrations induced by metro traffic

采用一种数值模型,并结合现场振动实测,对北京地铁4号线列车运行引起的振动对北京大学物理实验室内精密仪器的影响问题进行了研究,并对地铁4号线隧道内浮置板轨道的减振效果进行了探讨。该模型根据移动荷载作用下的动力响应解,把地铁列车运行引起的振动问题归结到计算频率-波数域内的传递函数和频域内移动轴荷载的问题上。传递函数采用三维周期性有限元-边界元耦合的数值模型来计算,移动轴荷载主要考虑为频域内轨道不平顺激励下的轮轨接触力。现场振动实测包括地铁列车与公交车单独引起的振动及两者的合振动测试。结果表明: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;在低频段,地铁列车单独引起的振动可能对精密仪器正常工作造成影响,公交车流单独引起的振动以及与地铁列车叠加的振动会对精密仪器的正常工作造成影响,仪器基座处应采取相应的隔振措施来减小这部分振动。

The effect on the sensitive equipment in the physics laboratory of Peking University due to vibrations induced by metro traffic and the isolation efficiency of floating slab track in tunnels on line 4 were studied by means of a numerical model and in-situ vibration measurement.In this model,based on the analytical solution of dynamic response excited by the moving loads,the vibrations induced by passage of metro trains can be calculated if the transfer function in the frequency-wavenumber domain and the moving axle loads in the frequency domain can be obtained.The transfer function is calculated using the three-dimensional coupled periodic finite element-boundary element model in the frequency-wavenumber domain,and the moving axle loads are considered as the contact force between wheel and rail due to the rail unevenness.The in-situ vibration measurement was performed outside and inside the laboratory,and the background vibration,the vibrations induced only by buses and metro trains,and the combined vibrations due to road traffic and metro traffic were measured.The results show that the floating slab track is an effective vibration isolation measure,which can efficiently reduce the vibrations in its work frequency range.At low frequencies the metro train induced vibrations may have effect on the sensitive equipment,and the buses induced vibrations and the combined vibrations due to road traffic and metro traffic affect the sensitive equipment,which can be reduced by the passive isolation measure under the base of equipment.