Seismic Response of Underground Structure Based on Centrifuge Shaking Table Test in Liquefiable Site

In order to study the effect of site liquefaction on the seismic response of underground structure, centrifuge shaking table test under liquefiable site condition was carried out. The seismic response law of underground structure in liquefiable site is obtained. And the attenuation degree of soil stiffness under different liquefaction degrees of the site is obtained by Pushover analysis method. The conclusions of the study are as follows. The peak total strain response of the sidewalls and plates of the model structure was well within the elastic range under the four loading conditions. The center column strains just exceeded the elastic strain limit for concrete under large earthquakes, with a low level of damage. This indicates that underground structure conforming to existing codes exhibits good seismic performance. The inter-story drifts of the structure in the liquefiable site are attenuated by 63%-76% compared with the site at the structural equivalent height for the four loading conditions. From the horizontal displacement of the site and the displacement attenuation ratio of the soil-structure system, although the liquefaction of the saturated sandy soil layer will lead to a larger horizontal displacement of the site, the reduction of the soil-structure stiffness ratio caused by the liquefaction of the site will still avoid the structure from experiencing a larger inter-story drift and serious damage. When applying the Pushover analysis method to simplify the analysis of underground structures in liquefiable sites, the most unfavorable conditions can be considered, and the soil modulus can be discounted to 3% of the initial modulus for calculation.