ABSTRACT
Analyses of the behaviors of tunnels subjected to the blast loading have been conducted by researchers worldwide. On the basis of 3D numerical analysis methods, Chille et al. (1998) studied the dynamic response of underground electric plant under internal explosive loading. They took coupled fluid-solid interaction into account, but not considered the nonlinearity and failure of rock and concrete as well as the interaction between different solid media. For traffic tunnels, Choi et al. (2006) carried out 3D FE analyses to investigate the blast loading and deformation in lining structures. They found that blast loading on lining structures was different from the normal one obtained by using CONWEP. The above two studies focused on underground structures in rock mass, as we all know, which are more resistant to internal blast loading than in soils. Dynamic analysis of circular lined tunnels under external blast loading was studied by Lu et al. (2005) and Gui and Chien (2006) using the FE program. Then, a difference method to analyze underground tunnels and cavities under blast loadings was adopted by Feldgun et al. (2008). Liu (2009) analyzed subway tunnels subjected to blast loading using FE method and modeled blast loading using CONWEP, while
1 INTRODUCTION
With the sustainable and rapid development of highway, railway, and urban transportation system, tunnels are widely used, and are becoming an inextricable part of the modern civil infrastructure. In recent decades, tunnel explosion accidents have resulted from gas leaks or terrorist attacks, which are proved to be a great threat to human society. Explosion inside a tunnel may not only damage the tunnel lining structures, but also lead to further loss of lives and properties of people. The blast behaviors of tunnel structures will be distinct from those of other structures caused by their features, especially (1) high longitudinal to cross-sectional dimension ratio, (2) pressures reflected from the tunnel boundary, (3) completely confined by the surrounding ground, and (4) coupled behavior of air blast inside the tunnel and wave propagation through the surrounding ground. On the basis of the above reasons, unique requirements, which differ from the design strategies for other structures, are essential to designing a tunnel to endure a potential blast; therefore, it is imperative to understand its dynamic response under the blast loading. Because of sociopolitical issues, it is normally difficult to carry out the experimental determination of tunnels’ dynamic response. Hence, applying
the high strain rate behavior of soils under blast loading was not considered. A similar study considering this soil characteristic was carried out by Higgins et al. (2012). However, their research only considered elastic stress-strain response of lining structures. And the explosive was simulated using the JWL equation of state. The performances of different shock absorbing foam materials, steel, and concrete tunnel linings subjected to explosion were compared by Chakraborty et al. (2013). They calculated blast loading by using a coupled fluid dynamics simulation. Nevertheless, using the JWL equation of state to carry out rigorous 3D simulations of lining tunnels in rock mass with properly simulated explosive load is rather unused in the literature because of the complex practical problems.
