Shaking table tests on the seismic responses of underground structures in coral

To reveal the seismic response of underground structures in coral sand, a series of shaking table model tests on underground structures at four different groundwater levels were carried out. The seismic responses of the coral sand and the underground structure were obtained and analyzed. The results showed that the excess pore pressure ratio and the liquefaction degree of coral sand increased with increasing groundwater level, resulting in a more significant separation between the sidewall and the surrounding soil. However, the acceleration amplification factor of the coral sand site, the dynamic strain and bending moment of the underground structure could be reduced. Moreover, the increase in the groundwater level contributed to the settlement of the ground surface. However, due to the presence of an uplift force caused by the liquefaction of the coral sand, the settlement of the underground structure decreased as the groundwater level increased. Furthermore, the distribution of the dynamic soil pressure under the groundwater level was found to be quite different from that under dry soil condition.

Automated summary

The seismic response of underground structures in coral sand is significantly influenced by groundwater level, with an increase in groundwater level leading to increased excess pore pressure ratio and liquefaction degree in the coral sand, as well as more significant separation between the sidewall and surrounding soil. However, it can also result in reduced acceleration amplification factor and dynamic strain in the coral sand site and underground structure. Additionally, the settlement of the ground surface is promoted by higher groundwater levels, although the settlement of the underground structure diminishes due to an uplift force caused by coral sand liquefaction.