It is observed that with the increase in saturation of soil, more blast energy is transmitted to the structure, which results in higher deformation. Further, the effect of saturation in sandy loam on tunnel stability is studied. Tunnels undergo extreme deformation in the case of sandy loam soil and clayey soil compared to rock cases. Sandy loam soil, being a highly compressible soil, exhibits non-linear and fluid-like behavior under high-strain loading such as explosions. Vertical displacement measured at the crown of the tunnel is used to determine the response of the tunnel. Geo-materials considered for the comparative study are sandy loam, saturated clayey soil, sandstone, and granite. Blast loading is simulated using the Jones–Wilkins–Lee (JWL) equation of state. Other materials including tunnel lining, reinforcement steel, and rock are modeled using Lagrangian formulation. Materials with fluid behavior such as air, explosives, and soil are modeled using ALE formulation. Finite element analysis has been carried out using LS-DYNA®, wherein the problem has been modeled using the multi-material arbitrary Lagrangian–Eulerian (MM-ALE) method. In the present study, the effect of various types of geo-material on the blast response of tunnels subjected to surface explosions is investigated. Limited study has been carried out considering this problem. As the shock wave propagates radially, its characteristics are likely to be altered by the geo-material. The blast wave generated has to travel through the geo-material before it interacts with the tunnel. Findings from one study cannot be applied to other geotechnical problems directly, especially in the case of tunnels subjected to surface explosions. However, geo-material is a naturally occurring material whose constitutive properties vary from region to region, making it highly unpredictable. Among these three materials, concrete and steel are manufactured materials and their properties can be controlled up to a certain extent. Prime materials involved in a problem such as underground structures are concrete, reinforcement steel, and geo-material surrounding the tunnel.
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