Large-scale experimental investigation of the effects of gas explosions in underdrains

This study involved the construction and explosion of a large-scale (80-meter-long) underdrain and detailed investigations of the damaging impacts of a gas explosion to provide an experimental foundation for similarity modeling and infrastructural designs. The experiment vividly recreated the scene and explosion damage of the “11.22″ explosion accident in Qingdao, China, thus allowing for evaluations of the movements and destruction of the cover plates. The damage mechanism was determined by analyzing the overpressure curves inside and outside the underground canal. It was determined that the cover plates were first lifted by the precursor wave, which induced a maximum overpressure of 0.06 MPa and resulted in explosion venting. The pressure entered the deflagration stage at the end of the explosion. The combustion wave overpressure reached 3.115 MPa close to the initiation point, and had a significant influence on the projectile energy of the cover plates there. Overall, 64% of the cover plates were only affected by the precursor wave, while 36% of the cover plates were subjected to both the precursor wave and the combustion wave; these cover plates were severely damaged. The results of this study provide fundamental insights relevant to the prevention and control of underdrain gas explosions.