Abstract：According to the transfer requirements，a transfer underpass of the Nijiaqiao Station of Chengdu Metro Line 8 is constructed under the existing station of Line 1 with zero clearance. Based on the project，the dynamic responses of the underlying transfer underpass under the influence of trains? dynamic loads from the existing metro station are compared and analyzed by in-situ tests and numerical simulation methods. The effects of the following three factors on the dynamic responses have been investigated，including ceiling thickness，sidewall thickness，and middle wall thickness. The results show that in the time domain，the overall dynamic responses of the closely underlying underpass tend to attenuate with the thickness ratio of the underpass ceiling to the existing metro station floor slab(RRF) or the thickness ratio of the middle wall to the side wall of the underpass(RMS)，but the attenuation rate decreases with the RRF or RMS. From this view，the RRF and RMS are recommended to adopt 1.5 and 1.0 as the optimized values，respectively. The dynamic response magnitudes (i.e.，acceleration peak values，ignoring their directions) of the underpass decreases spatially from top to bottom and from the middle to the sides，i.e.，ceiling＞middle wall＞sidewall＞floor slab. The frequency domain shows that the underpass has a dynamic frequency response ranging from 40‐160 Hz. The increase of RRF and RMS have no influences on the frequency response distribution but have appreciable suppression effects on the dynamic magnitude，especially high-frequency dynamic magnitude.
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2023, Vol. 42 
