Numerical Analysis of Underground Tunnel System with GFRP Shield Against Internal Explosion

The rapid growth of population in metropolitan cities has led to severe congestions urging to efficient utilization of underground spaces. Immediate and deep underground spaces are widely utilized as subway tunnels for meeting the transportation requirements. However, due to high population density in a confined space, they have become easy targets to terrorist attacks and intentional blast events. In the present study, an innovative technique incorporating the use of GFRP (Glass Fiber Reinforced Polymer) shield over RC tunnel has been proposed. The response of underground RC tunnels surrounded by two different surrounding soil conditions is investigated using the 3D-FE (Finite Element) method. The influence of 80 kg TNT (Trinitrotoluene) explosive charge is studied and the performance of the tunnels is quantified in terms of acceleration and strain time histories. It is observed that the utilization of GFRP shield results in improved performance of RC tunnels against internal explosion. Also, the GFRP shield reduces the risk of long-term geotechnical effects in soil. Thus, it may be adequately utilized as a shielding layer over RC tunnels in order to improve the safety and blast resistance.