In this study, finite element (FE) analysis of underground structure is carried out, which is subjected to the internal blast loading and the structure is surrounded with soil media. Three different methods to analyze the effect of blast loading on structure, i.e. ConWep, smooth particle hydrodynamics (SPH), and couple Eulerian-Lagrangian (CEL) are used for the simulation of blast loading using ABAQUS/Explicit (R) . Concrete damage plasticity (CDP), Mohr-Coulomb, Johnson-Cook (JC) plasticity model, Jones-Wilkins-Lee (JWL) equation of state and ideal gas are utilized for defining behavior of concrete, soil, steel, explosive and air, respectively. FE analysis is performed to compare the behavior of structure under different blast modelling methods. The effect of different explosive weights is considered to see the impact of the blast load on the structure. For parametric analysis, three explosive weights, 3kg, 5kg, and 10kg of TNT (trinitro toluene), and three concrete grades, M30, M35, and M40 are considered to see the stability of the structure. The effect of varied explosive weights and varied concrete grades is compared in terms of stress, pressure, and displacement at critical locations of the structure. The outcome of this shows that the change in explosive weight and concrete grade considerably affects the stability of the structure. As the explosive weight increases, damage to the structure increases, and with the increase in the concrete grade, the blast load resistance capacity of the structure increases. It is observed that buried part of the structure is more resistant to blast load compared to the structure visible above ground.

This study investigates the dynamic response of RC lined rectangular tunnel in soil subjected to internal blast load. For this purpose, a three-dimensional non-linear finite element model comprising of tunnel lining, reinforcement, and soil is analyzed in Abaqus/Explicit. The behaviors of soil, concrete, and steel are simulated using Drucker-Prager plasticity, concrete damaged plasticity, and Johnson-Cook (J-C) plasticity models, respectively. The effect of various grades of concrete (C30, C40, and C50) and lining thickness (300 mm, 400 mm, and 500 mm) on the dynamic response of the tunnel structure and the surrounding soil is investigated. It is observed from the results that deformations of tunnel lining increase with a decrease in the grade of concrete and decrease with an increase in lining thickness. The results suggest it is advantageous to increase the thickness of the liner for a certain grade of concrete, rather than increasing the grade of concrete for the same liner thickness for better blast response. The vulnerability of the tunnel liner is high at the roof-sidewall junction suggesting the need for better reinforcement detailing.