Finite element modeling

The finite element software Abaqus/Explicit has been used for the present analysis of rock tunnel subjected to internal blast loading. The model dimensions of the tunnel are 30m x 30m of cross-sectional dimensions and 35m of extruded length [6,26]. The dimensions of the finite element model are based on boundary convergence study. Initially, the thickness of tunnel lining has been kept as 0.22m and later, it has been varied as 0.35m, 0.45m and 0.55m. Four different depth of overburden has been considered in the present analysis are 5m, 7.5m, 10m and 12.5m. The tunnel has a diameter of 6m. The element size of the model has been kept as 0.2m based on the mesh convergence study. The tunnel lining and rock model has been meshed with an element type of C3D8R (Eight-node brick element with reduced integration). Moreover, the Eulerian Model of Trinitrotoluene (TNT) and air has been modelled as EC3D8R (8-node linear brick, multimaterial, reduced integration with hourglass control). The boundary conditions at the base of the rock model have been restrained in all directions as the rock has infinite depth. The front and rear of the model has been restrained in all directions and the deformations are allowed in the vertical direction. The right and left sides of the model were allowed the deformation in vertical directions and restrained in other. The finite element model has been shown in Figure 1.