Analysis of curved tunnels in soil subjected to internal blast loading

The present study deals with three-dimensional nonlinear finite element (FE) analyses of tunnels with curved alignment in the longitudinal direction, subjected to internal blast loading. Blast load is simulated using the coupled Eulerian-Lagrangian (CEL) analysis tool available in FE software Abaqus/Explicit. The explosive and the surrounding air have been modeled using the Eulerian elements. Soil and concrete lining are modeled using the Lagrangian elements. The trinitrotoluene (TNT) explosive is modeled using Jones-Wilkins-Lee (JWL) equation-of-state (EOS). The Drucker-Prager plasticity model has been used to simulate the strain rate dependent stress-strain response of soil. The concrete damage plasticity model has been used to simulate the strain rate dependent behavior of concrete. The deformation, stress and damage response of the tunnel lining and the surrounding soil are investigated herein. Attenuation of blast-induced stress wave in soil is also studied. It is observed that deformation and damage of tunnel lining and soil are dependent on the location of explosive position inside the tunnel and the radius of curvature of the tunnel. Higher deformation and damage is observed in a tunnel with a lesser radius of curvature. A significant amount of ground heave is observed in all analyses.