Abstract: Explicit FEA method is employed to investigate the effect of aluminum foam in tunnel blast protection.A three-dimensional finite element model is established, including the ground layer, tunnel, aluminum foam layer, air layer and the interaction between them.The mechanical response of the tunnel under 150 kg TNT blast load in the center of the tunnel for three cases of protective layer thickness of 0 cm, 15 cm and 20 cm is analyzed.To overcome the shortcomings of previous studies that simplified the blast wave load acting on the tunnel as the triangular load, an alternative wave source layer is used to simulate the blast wave load, and this load is calculated according to the explosive equivalent and explosive distance.An air layer is placed between the alternative wave source layer and tunnel, with its thickness set as 24% of the tunnel radius according to experience from numerical simulations.These settings not only enable the simulation of multiple reflections of blast waves on the tunnel inside surface, but also significantly enhance the calculation efficiency and accuracy.Dynamic response of the tunnel structure and the surrounding soil under different blast loads is analyzed based on the numerical simulation results, and the blast protection effect of different thicknesses of aluminum foam layer is discussed from the perspectives of blast wave pressure, blast wave impulse, acceleration response and soil liquefaction.It is show that the aluminum foam lining can effectively absorb the blast wave energy and effectively reduce the damage of the tunnel.10 cm thick aluminum foam protection layer can reduce the blast wave impulse by 17%.With increasing thickness of aluminum foam, dynamic effects, such as acceleration, velocity and deformation of the tunnel structure and the surrounding soil, reduce obviously.Away from the point of explosives, the blast wave pressure and impulse significantly attenuate, and when the axial distance is greater than 6.5 m, the blast wave pressure and impulse are significantly reduced.The results of this analysis can provide a basis for the design of blast protection in high-risk areas of the tunnel.