STUDY OF SHOCK IMPEDANCE EFFECTS IN A ROUGH WALLED TUNNEL.
INSTITUTE FOR DEFENSE ANALYSES ARLINGTON VA SCIENCE AND TECHNOLOGY DIV
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The paper deals with the problem of protecting deep underground installations from damage when surface nuclear explosions occur near their tunnel entries. The physical phenomena that occur when an air of long duration i.e., one caused by a nuclear explosion passes over the entrance to a tunnel are analyzed. The initial pressure of the shock wave which is subsequently driven down the tunnel is determined, and five sequentially related impedance mechanisms are postulated as controlling the propagation down a roughwalled tunnel. These are entry diffraction, buildup, turbulent choke, wall roughness and feedback. Laboratory and limited field tests confirm the theory for all five impedance mechanisms. But definite experiments at 1000 psi or at the level of nuclear explosions have not been performed. Suggestions are made for determining the site and design of tunnels and for the control and decoupling of underground explosions. Author
- Civil Engineering