Abstract:  The field research was made on the test of vibration response of key positions in Shanghai Jinshan existing railway in the case of passing of trains .It is pointed that, the peak vertical acceleration on the surface of subgrade bed in the zone of common subgrade varies from 95.1 cm/s2 to 110.4 cm/s2, and the peak transversal acceleration varies from 89.8 cm/s2 to 116.4 cm/s2. The response frequency of vibration of subgrade bed is focused between 30 Hz and 50 Hz. The vibration energy is left about 30 percent when it arrives at the foundation, and then it will make the vibration level of shallow foundation soils increase. Within 20 meters in the zone of bridge-subgrade transition, the vibration quantity of track and subgrade varies significantly in the longitudinal direction and is relatively higher in the middle of transiton zone. The vibration quantity reaches the maximum at the place where the settlement of subgrade in the bridgesubgrade transition is largest.
 

Key words: exsiting railway, common subgrade, bridgesubgrade transition, vibration response