Blast mitigation by water in a bag on a tunnel floor

Mitigation of blast wave, caused by explosion of explosives, from a straight tube using water in a bag (water bag) was evaluated. The length of the tube was 330 mm and the cross-section area was 30 x 30 mm2. One end of the tube was closed. The water bag was placed on the floor or closed end wall of the tube near the explosive. The thickness of water was 3 mm. A specially designed small detonator, which contains lead azide of 100 mg, was ignited near the closed end wall of the tube. The blast pressure outside the tube was measured and examined. The blast wave was remarkably mitigated by the water bag. Equivalent ratio analysis revealed that the glass beads absorbed 33%-45% of explosion energy.