Performance of Buried Tunnels Subjected to Surface Blast Incorporating Fluid-Structure Interaction

Abstract

This paper uses finite-element techniques to investigate the performance of buried tunnels subjected to surface blasts incorporating fully coupled fluid-structure interaction and appropriate material models that simulate strain-rate effects. Modeling techniques are first validated against existing experimental results and then used to treat the blast-induced shock-wave propagation and tunnel response in dry and saturated sands. Results show that the tunnel buried in saturated sand responds earlier than that in dry sand. Tunnel deformations decrease with distance from the explosive in both sands, as expected. In the vicinity of the explosive, the tunnel buried in saturated sand suffered permanent deformation in both axial and circumferential directions, whereas the tunnel buried in dry sand recovered from most of the axial deformation. Overall, response of the tunnel in saturated sand is more severe for a given blast event and shows the detrimental effect of pore water on the blast response of buried tunnels. The validated modeling techniques developed in this paper can be used to investigate the blast response of tunnels buried in dry and saturated sands.