Abstract

A deeply buried straight-walled round-arch structure in a rock medium is taken as the research object in this study. Model tests of the underground structure subjected to multiple 45° side–top far-field explosions, with a scale of 1:20 and a proportional explosion distance of 1.68, are designed and carried out to study the dynamic responses, failure modes and damage mechanisms of the deep-burial underground structure after ground shocks induced by explosions. The macroscopic phenomena and measured data of the tests are reported and analyzed. The results show that after the first explosion and the second explosion, the surface of the surrounding rock model and the reserved charging port are seriously damaged. In contrast, the damage to the underground structure is relatively slight. The overall structure produces downward-bending deformation, and an axial crack occurs on the inner surface of the vault. The peak accelerations of the underground structure after the explosions are significant, with values reaching 2400 g, and the corresponding prototype value can exceed 120 g. After the first explosion, the damage to the upper part of the surrounding rock and the axial crack at the vault lead to a decrease in local stiffness. The crushed areas and cracks of the surrounding rock formed by the first explosion intensify the attenuation and leakage of shock wave energy during the second explosion, resulting in reductions in the ground shock pressure on the structure, the structural strain and the acceleration response. It is also found that on the floor of the prototype structure, the maximum spectral acceleration in the range of the natural vibration period of the human body exceeds 10 g, which poses a safety threat to the usage of underground structures. The research results in this study provide an experimental reference for the anti-explosion design of deeply buried underground structures and provide a basis for the establishment of performance and vulnerability indicators for straight wall round arch underground structures subjected to far-field explosions.

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