ROOT CAUSE OF AN UNCOMMON ELECTRONIC DETONATOR FAILURE

Abstract

Detonator failures during a blast are deemed unsafe and can disrupt the productivity of a project. Therefore, it is desirable to understand the origin of such an event when it happens. A commonly observed detonator failure during blasting is the crushing of the detonator shell due to excessive dynamic pressure from previously fired neighboring blastholes. In a tunneling site in Japan, it was found that detonators failed to initiate with their shells and primary explosive intact. However, their capacitors were discharged due to some damage to the application-specific integrated circuits. This type of detonator failure is distinctly different from more commonly observed failures. Such incidents have not been reported elsewhere. Various measures were conducted to diagnose the problem at the site. This paper formulates a theory that can explain the observed detonator failure and predict the measurements and observations. The theory was initially discovered in a laboratory setting some 60 years ago and is based on the electromagnetic pulse (EMP) generated when detonating the explosive charge. In this work, the EMP generated by an explosive charge in rock was not investigate nor were the EMP characteristics and EMP generated during blasting studied. Rather, this study involved applying a hypothesis to predict an uncommon occurrence of electronic detonator failure, which subsequently led to a successful redesign of the aforementioned detonator circuit and eliminated the detonator failure issue.