ABSTRACT
Abrasive waterjet drilling is an advanced excavation that can effectively deal with overbreak, a primary issue of conventional tunneling methods. Abrasive waterjet drilling precisely removes the target rock with continuous impact using high-pressure water and abrasives. Thus, abrasive characteristics have been recognized as parameters that affect the drilling performance. In this study, an experimental approach was utilized to investigate the effect of abrasive characteristics on excavation performance. The abrasive flow rate and particle size were considered as abrasive characteristics. The experimental results showed that the drilling width was expanded with a higher abrasive flow rate and particle size. However, the drilling depth decreased as the abrasive flow rate increased, and the effect of the abrasive size on the depth varied according to the abrasive flow rate. In addition, the impact of the backflow effect, which inevitably occurs in abrasive waterjet drilling, on the performance was analyzed. As a result, it was found that the three stages of the impact of the backflow effect were influenced by the abrasive characteristics. This research is expected to be a fundamental study to enhance understanding of the abrasive waterjet drilling mechanism, facilitating its application in excavation sites.
