Fabricated Structure Adjacent To Metro Vibration Characteristics And The Three-dimensional Vibration Reduction Measures

The rapid development of the metro provides efficient and fast travel choice for the urban population,but at the same time,uncomfortable problem and environment pollution induced by vibration and noise of trains is arousing public concern.Therefore,it is necessary to research on vibration caused by train and measures for vibration reduction.Effect on the vibration of the adjacent buildings was analyzed.The distribution of the building within a50 m radius around the Nanjing metro was investigated,Prefabricated frame structure adjacent to Nanjing metro was selected as the research object.Experimental research and finite element analysis of the ground vibration caused by train and vibration of prefabricated frame structure adjacent to the metro was carried out.frequency characteristics and the spread rules of vibration of prefabricated frame structure was studies.Vibration reduction strategies and suggestions of Nanjing metro were put forward.The main work and results as follows:(1)Research on dynamic response of prefabricated frame structure induced by the metro train vibration was carried out.The results show that maximum vibration velocity can be used to evaluate the vibration response of prefabricated frame structure.The vibration velocity peak value compared with the prescribed limit value,and vibration vibration velocity peak value of prefabricated frame structure was less than 0.2mm/s,which met the specified requirements.Under the metro vibration,practical measure research and finite element analysis results of beam and floor slab of prefabricated frame show that the vertical vibration significantly greater than horizontal vibration,That is,vibration of the adjacent building which induced by metro train has directivity and vertical vibration takes a leading role.(2)Research on vibration propagation of prefabricated frame structure induced by the metro train vibration was carried out.The results show that the vertical vibration velocity presents the trend of gradually increasing with the increasing of the storey number,although the increase in the numerical change is small.But the trend of measured results curves change of measuring point on floor slabs is obvious.Vibration is not monotone changing,when it is diffused on the same floor,and there exists a vibration amplifying zone around 15 meters to25 meters from metro rail.The measured data confirmed that the phenomenon mentioned in previous literature,that there exists a vibration amplifying zone in a certain distance to vibration source.Research on frequency characteristics of prefabricated frame structure induced by the metro train vibration was carried out.The results show that,for median-low structures(e.g.,the four-story building studied by this paper),frequency of measured response of the building under the metro vibration are mainly concentrated in 10~30 Hz.The frequency played a leading role appears near 15~20Hz.Vibration frequency of FEA is slightly different from the measured results,and both of them are low frequency vibration.The frequency characteristics do not change the increasing of the storey number.The existing vibration control theory and technology were used for reference.Combining with vibration isolation methods at the present stage and considering vibration reduction techniques which have been used in part of Nanjing metro lines,vibration reduction strategies and suggestions of structures adjacent to Nanjing metro are put forward.