Dynamic centrifuge tests for influence of vertical inertia force of overburden soil on earthquake damage response of shallow-buried underground frame structures

Previous researches have showed that the columns under different axial compression ratios performed different lateral deformation capacities, which is the key factor of aseismic performance of the shallow-buried subway frame structures. In this study, dynamic centrifuge model tests on earthquake damage to underground structure are carried out. The model tests aim to shed lights on the effect of the increased axial compression ratio of column, which is induced by the vertical earthquake excitation, on earthquake damage responses of shallow-buried underground frame structures. To simulate the effect of vertical inertia force of overburden soil, the steel grits are mixed into the overburden soil layer. Test results indicate that the way of mixing the steel grits into the overburden soil layer has little influence on dynamic characteristics of soil-structure system and relative horizontal displacement between ceiling slab and bottom slab due to seismic excitation. The increased vertical inertia force of overburden soil significantly changes the contact pressure distribution between underground structure and surrounding soil, and the stress states of structural member are changed accordingly, leading to the increase of axial compression ratio of the key vertical load bearing column in the underground frame structure. Consequently, increasing vertical inertia force of overburden soil effectively increases the stresses of the structural frame and axial compression ratio of middle columns, so that the underground frame structure is more susceptible to seismic damage. © 2019, Editorial Office of China Civil Engineering Journal. All right reserved.