Non-linear FE investigation of subsurface tunnel with gfrp protection against internal blast

Abstract

The contribution of subsurface tunnels in the present time is imperative. However, in the past few decades they have become a target to explosives and terrorist attacks. Considering the strategic importance and susceptibility of tunnels in case of internal explosion, the blast mitigating design has become very critical. In this work, a novel concept involving the use of glass fiber reinforced polymer (GFRP) layer to strengthen the reinforced concrete (RC) tunnel lining against these incidents has been introduced. Metro underground tunnels exposed to internal blast with two different surrounding soil conditions are investigated. The analysis is done using explicit 3D-Finite Element (FE) method. A comparative study towards the damage due to explosion of different trinitrotoluene (TNT) charges is executed. It is observed that the application of GFRP layer reduces the displacement and stress values at key points in tunnel and ground surface under different explosive charges and soil conditions. Also, there is a reduction in the tunnel damage as well as the risk of long-term geotechnical effects in soil. Thus, GFRP may be effectively utilized as an additional layer to improve the resistance of RC tunnel against blast instead of designing an uneconomical rigid structure. Consequently, the present study contributes towards the safety and blast mitigation design of RC tunnels. © 2022 Elsevier Ltd