ABSTRACT
In Sweden, drilling and blasting is generally regarded as the predominant excavation method for tunnel construction. While many studies focus on the blast performance within the tunnel perimeter, few studies have examined the effects of the induced cracks behavior in these designs (where the charge is decoupled). This work aims to improve the understanding of crack initiation and development during contour blasting. The investigation consists of a small–scale blast test to study the crack development around a blasthole using the Digital Image Correlation (DIC) technique. The experimental setup involved a cylindrical rock–like sample with a central blasthole and a decoupled PETN cord (Pentaerythritol tetranitrate) explosive charge by 3.9. The data was collected with an ultra–highspeed camera (UHSC) and processed using image engineering. Based on the experiment, numerical modelling was carried out to compare and investigate the behavior of the cracks. The analysis approach included tracking crack development using the strain values for both experiment and numerical modelling. These results emphasize the importance of combining the strain analysis in different directions to find the crack development sequence. The experimental and numerical results show good consistency, providing valuable information on crack development behavior around a blasthole.
