Minimizing overbreak and underbreak using abrasive waterjet technology in underground excavation

摘要

Major metropolitan areas increasingly require the construction of underground spaces such asrna tunnel for the effective use of limited urban areas. The blasting method is broadly used for rock excavationrnworldwide because of its efficiency. The blasting induced overbreak and underbreak occur in the vicinity ofrnthe underground opening; the overbreak and underbreak can decrease the reliability of underground spacesrnand increase support (reinforcement) cost and time. An abrasive waterjet technology can be effectively utilizedrnalong with the blasting method during the rock excavation process by forming a clear outline of a tunnel andrnunderground space in advance, which results in a reduction of overbreak and underbreak during the blastingrnprocess. In this study, an alternative excavation method using the abrasive waterjet to minimize the overbreak andrnunderbreak is introduced. In addition, experimental and analytical studies are performed to verify the minimizingrneffects of the overbreak and underbreak in tunnelling.