Shock isolation and absorption of continuous girder bridge subjected to blast loading in the underground tunnel

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Dynamic responses of a continuous girder bridge with the rubber bearings, together with its shock absorption effects when the viscous dampers are installed respectively in the transverse direction of the structure and in its longitudinal direction, under the blast loading in an underground tunnel adjacent and paralleled to the bridge are numerically analyzed. The LS-DYNA software is used to establish a three-dimensional coupling model consisting of the tunnel, soil around, water in the channel and the continuous girder bridge. For this model, some processes, such as the calculating and loading of the in-tunnel explosion, the selecting of the constitutive models of soil and concrete material, the defining of the water model and the water-pier and water-soil interaction, the introducing of boundary condition of far-field soil, and the building of mechanical models of the rubber bearing and the viscous damper, are carried out appropriately. Based on numerous and systematic example analyses, it is demonstrated that the rubber bearings set on the continuous girder bridge show better shock isolation performance under an impact from an adjacent in-tunnel explosion, and in general there is an increasing trend in the deformations and internal forces of the bridge slab while the water-level is rising gradually from a zero start point. Besides, not only are the shock absorption effects of the transversely-set dampers on the transverse and vertical deformation and the internal force of the bridge slab disclosed, but also some shock absorbed laws of the longitudinally-set dampers to the longitudinal and vertical deformation and the internal force of the bridge slab are also summarized. This provides an important reference for the research and practice of explosion-proof bridge subjected to the underground and underwater blast waves.