Rock Tunnel Performance Under Blast Loading Through Finite Element Analysis

Underground rock tunnels have been an integral part of human civilization, since several decades. The construction and continuous use of these underground structures have become an essential part of metro cities. Moreover, tunnels and other underground utility construction has an important role as strategic structures, especially in defense sector. Due to these reasons, terrorists and other anti-social activities have targeted tunnels to inflict damage by using explosives that cause blasts. Therefore, tunnels and other underground structures should be design and strengthened against blast loading. In this paper, an attempt has been made to understand the behaviour of three different rock tunnels in commonly found three different rocks i.e., Granite, Basalt and Quartzite. The geometry of the finite element model has been kept constant for each rock type. The nonlinear elastoplastic behaviour has been simulated through Mohr-Coulomb, Johnson-Cook and Concrete-Damage-Plasticity constitutive material models for rock, reinforcement and concrete liners respectively. In addition, the 100 kg of trinitrotoluene (TNT) explosive has been considered throughout the paper for different cases. The advanced method of modelling, i.e., coupled-Eulerian-Lagrangian method has been considered for modelling TNT and air inside the tunnel to simulate internal blast loading. Deformation, shock wave velocity, acceleration, pressure, stress, strain energy and damage are the different parameters extracted, analyzed and discussed in aftermath of internal blast loading effect on rock tunnel. The finite element modelling has been validated through experimental and numerical results presented in the published literature. The finite element software Abaqus has been used for the simulation of internal blast loading in rock tunnel.