Dynamic responses of buried arch structure subjected to subsurface localized impulsive loading: Experimental study

A structural model experiment was carried out on a buried scaled-down reinforced-concrete arch structure subjected to underground close-in explosions. The aim of the experiment is to provide believable results of dynamic responses of large-span structures, including the dynamic loads, deflections, strains and failure modes. To achieve this objective, blast experiments were carried out under 0.6 kg, 3 kg, 6 kg and 17.4 kg TNT charges, respectively. Distribution laws of the applied dynamic loads, deflections, strains, accelerations and the failure modes of the arch were revealed. Different from the quasi-uniform distribution style subjected to far-field explosions, the dynamic loads applied on the buried arch subjected to close-in explosions have tense local effects and render a triangle-like distribution style. According to the tested deformations and strains, it can be concluded that subjected to close-in explosions, the buried arch deforms at a dominant flexural mode, companying with compression mode. Spalling, tensile cracks and shear failures of the concrete and yielding of the steel bars are the main failure modes of the blast-loaded arch. The arch will collapse after four or five plastic hinge lines formed. The experimental data are helpful for engineers and well support further theoretical analysis.