Dynamic Analysis of a Twin Tunnel in Soil Subjected to Internal Blast Loading

Abstract

The present study deals with three-dimensional (3-D) nonlinear finite element analyses of a twin tunnel in soil with reinforced concrete (RC) lining subjected to internal blast loading. Blast load has been simulated using the coupled Eulerian Lagrangian (CEL) analysis tool available in finite element software Abaqus/Explicit. Soil mass and RC lining have been modeled using 3-D eight node reduced integration Lagrangian elements (C3D8R). Beam elements (B31) have been used to model reinforcement of RC lining. A 50 kg trinitrotoluene (TNT) charge weight has been used in the analysis. Eight node reduced integration Eulerian elements (EC3D8R) have been used for modeling TNT explosive and surrounding air. Drucker–Prager plasticity model have been used to simulate strain rate dependent behavior of soil mass. For simulating strain rate dependent behavior of concrete and steel, concrete damaged plasticity and Johnson–Cook (J–C) plasticity models have been used, respectively. The explosive TNT has been modeled using Jones–Wilkins–Lee (JWL) equation of state. Investigations have been performed for studying the deformation, damage of RC lining and surrounding soil mass. Pressure in the RC lining and surrounding soil mass, caused by explosive induced shock wave has been studied for both tunnels. It is observed that damage and deformation of RC lining and soil mass are dependent on charge weight and clearance between the tunnels.