Development and Advance in Tunnel Structures Subjected to Internal Blast Loads: A Comprehensive Review

Tunnels and subways have become essential features of the civil infrastructure system in recent years. Explosions inside tunnels and subway stations could endanger persons trapped inside and cause structural damage, resulting in more deaths and financial losses. Thus, a blast-resistant tunnel design is required to reduce the damage and fortify the tunnel against blast-related disasters. Several relevant literature publications on the subject were explored to acquire a better knowledge of how tunnels perform when subjected to blast loads. This paper examines various aspects of the behaviour and performance of tunnels subjected to internal explosions. It begins with a discussion of the importance of tunnels, then it explores the categories of internal explosions and their potential causes, the characteristics of blast waves in tunnel structures, and their effects on tunnel structures. It then delves into the response of blast resistance tunnels and the methodologies employed for assessing the blast resistance of tunnels, such as analytical approaches, numerical simulations, experimental testing, and the main failure modes of tunnels subjected to internal blast loading. Additionally, the factors that influence tunnel response are reviewed including the use of high-performance materials such as fibre-reinforced polymer (FRP) composites as well as ultra-high-performance concrete (UHPC). The review concludes by identifying potential areas for further research and development in the field of blast-resistant tunnel engineering.