| Summary: | 碩士 === 國防大學理工學院 === 軍事工程碩士班 === 99 === This study experimentally investigated the behavior of shock waves propagating from a portal explosion to the inside of a tunnel by using LS-DYNA software to simulate. The results of the blast experiments were compared with numerical results.
The blast experiments were conducted by blowing up different weights of C4 explosive in near-surface burst, external tunnel explosion, and external tunnel explosion with blast wall. We measured the blast pressure and impulse inside the tunnel after blasting to establish an empirical formula and a numerical model.
The results of the blast experiments indicated that the Z (scale distance, Z=m/kg1/3) was between 2.15 and 3.26. From analyses of the empirical results of blasts in both near-surface burst and external tunnel explosion, the blast pressure and impulse of the near-surface burst can be converted to obtain an empirical formula for the blast pressure and impulse in the tunnel (three times of the tunnel diameter) when the blast occurs outside the tunnel. The blast pressure and impulse of external tunnel explosion with blast wall at various distances (1.5 to 2.5 times of the tunnel diameter) were lower than when no blast wall were in place, indicating that blast wall can effectively attenuate blast effects. The empirical formula for the blast pressure and impulse in the tunnel can be obtained through conversion from the empirical equation for the near-surface burst.
The Arbitrary Lagrangian-Eulerian (ALE) algorithm was used to simulate the explosive and air in Eulerian mesh, tunnel and ground in Lagrangian mesh. Comparing the numerical simulation and blast experiment results, the blast pressure error at the tunnel entrance was within 37%. When L/D (measurement point/ tunnel diameter) extended by 1 to 3 times, the blast pressure error was within 115%.
|
|---|
