Simultaneous Initiation of Nitromethane in Two Holes by Pulsed Wire Discharge for Crack Control of a Concrete Block

In order to rescue the victims from collapsed concrete structures, rescue routes should be made quickly. Given the presence of the victims, breaking concrete into pieces should be avoided. The purpose of this study is to divide concrete into arbitrary shapes using as little energetic material as possible. In this study nitromethane (NM), which undergoes a deflagration reaction, was used as an energy substance. Two NM charges placed into a concrete specimen were simultaneously ignited by pulsed wire discharge to maximize the power of the deflagration. As a result, a fracture surface was formed between the charge holes of the specimen, and an approximately symmetrical fractured shape was obtained. In numerical analysis with spalling failure as the failure condition, a fracture shape very similar to the model experimental result was obtained. Furthermore, the formation of a crack by the interference of stress waves propagating from two charge holes was demonstrated.