Modeling of Surface Blast Effects on Underground Structures

Explosions on the ground surface develop shock waves that travel through the subsurface and can cause significant damage to underground structures, such as tunnels. Factors, such as amount of explosives, distance from the source to the structure, and nature of the intervening medium determine the magnitude of stresses induced at the structure. This paper presents results of centrifuge model tests and numerical model analyses where the effects of surface blasts on underground tunnels were studied. Both centrifuge modeling and numerical analyses offer different means of modeling the behavior of soil and underground structures under dynamic, very large strain loading, such as explosions. The results of centrifuge model tests, in the form of measured strains on underground tunnels, are presented. Numerical modeling was used to investigate the effects of specific variables, such as mass of explosives and thickness of soil cover.