Dynamic analysis of curved tunnels subjected to internal blast loading

Abstract

The present study deals with three dimensional nonlinear finite element analyses of underground tunnels with curved alignment in the longitudinal direction, subjected to internal blast loading. Blast load is simulated using coupled Eulerian-Lagrangian (CEL) analysis tool available in finite element software Abaqus/Explicit. A 50 kg explosive weight is used in the analysis. The explosive and the surrounding air are modeled using the Eulerian elements. Soil, concrete lining are modeled using the Lagrangian elements. The explosive (TNT) is modeled using JWL equation-of-state (EOS). Drucker-Prager plasticity model have been used to simulate strain rate dependent behavior of soil. The concrete damage plasticity model has been used to simulate strain rate dependent behavior of concrete. The deformation, stress and damage response of tunnel lining are investigated. Attenuation of blast induced stress wave velocity in soil has also been studied. It is observed that deformation and damage of tunnel lining and soil are dependent on the location of explosive positions inside the tunnel. Higher deformation and damage are observed in tunnels with lesser radius of curvature. Significant amount of ground heave is observed in all analyses.