Shock Environment Assessment of Underground Arch-Wall Structures Subjected to Ground Shock

Underground structures provide more effective protection against air blast and surface explosions compared with their aboveground counterparts, but their safety is threatened by subsurface detonations due to the strong coupling between the explosion energy and the surrounding soil. For a certain standoff distance between the explosion center and buried structure, the inside equipment may be damaged by the strong vibration within the structure, while the structure itself experiences minor or even no damage. This strong vibration, not damaging the main structure, but damaging the contained equipment, is termed in-structure shock. In the present study, a theoretical model is established to evaluate the in-structure shock environment of a buried arch-wall structure subjected to overhead subsurface detonation. Dynamic soil-structure interaction, as well as different response modes including local deflection and global rigid body motion, are incorporated to determine the response of the concerned structural member. A small-scale field test was conducted to validate the proposed model. Subsequently, shock response spectra are employed to characterize the in-structure shock level within the structure. Furthermore, a parametric study is conducted to examine the influence of governing parameters on the structural response and consequent in-structure shock level, including soil parameters, ground shock characteristics, scaled distance, and location. The present study not only provides a method for quick assessment of the in-structure shock level of underground arch-wall structures subjected to overhead ground shock in preliminary design but also extends the theoretical prediction of buried structure response from the directly loaded members to opposite ones.