Test and damage assessment of shallow buried RC tunnel under explosion

As a major element of the transportation network, tunnels are unavoidably threatened by accidental loads such as vehicle bombs and tank truck explosions. The goal of this research is to explore the dynamic characteristics and damage assessment of tunnel structures under contact blast loads. First, three scaled-down reinforced concrete tunnel models were made, and the explosion test and static loading test were carried out successively to evaluate the axial residual bearing capacity, axial displacement and failure mechanism of the tunnel. Secondly, the finite element model is built by utilizing LS-DYNA, and the reliability of the finite element method is confirmed by comparing the data of the explosion test with the static loading test. At the same time, the calculation method for damage coefficient and the classification criteria for damage grade based on axial residual bearing capacity are presented. Then, based on the finite element method, the propagation process of the explosion shock wave in the tunnel and the damage mechanism of the tunnel are investigated. Finally, seven explosion scenarios are developed, the damage degree of these seven tunnels under the blast load is quantitatively analyzed, and further anti-blast design ideas are put forth. The study in this article may give an intended reference for the damage assessment, anti-explosion design and strengthening work of reinforced concrete tunnels.