Abstract: A shaking table experiment was conducted on a shield-enlarge-dig type subway station structure in sandy ground subjected to the near field earthquake and the far field earthquake. The horizontal displacement, surface deformation, acceleration, earth pressure response of the model ground and the acceleration and strain of the model structure of sandy soil are analyzed. The measured data substantiate that, the seismic response of soil-structure interaction system is more intense to the ground motion with low-and medium frequency. The subway station structure subjected to strong earthquake motions has obvious spatial effect, and the existence of underground structure will result in a change in the deformation distribution mode of ground surface. The acceleration response of columns of the model structure increases gradually from bottom to top as result of a low-intensity earthquake, while for the high- intensity earthquake, the acceleration response presents a law of increasing first and then decreasing. The acceleration response of the top plate is the biggest, followed by middle plate and bottom plate is the smallest under seismic action. And in addition to this, the acceleration response of the model structure is roughly equal to that of the model soil, and the dynamic earth pressure of the side wall increases gradually from bottom to top as result of the low-intensity earthquake; while for the high-intensity earthquake, the acceleration response of the model structure significantly surpasses that of the model soil, and the maximum value of earth pressure occurs at the arch shoulder and the middle part of the expanded tunnel. The earthquake damage mechanism of the shield-enlarge-dig type subway station structure is given based on the macroscopic phenomena of model structure after shock and the stretching strain amplitude under different ground motions.

Key words: shaking table test, shield-enlarge-dig type subway station, seismic response, near and far field earthquake