Analysis of Abrasive Reusability Performed with Different Energy Parameters in Rock Drilling Using Waterjets

Conventional mechanical drilling methods have problems such as high levels of vibration, noise, and dust. To address these issues, rock drilling using abrasive waterjets has become widespread in geotechnical engineering. Waterjet drilling reduces vibration, noise, and stress during the non-contact drilling process and is safe for use in hazardous or populated areas. However, the cost of abrasive is a problem that needs to be addressed. This study suggests recycling the garnet used in waterjet drilling to improve cost efficiency. The drilling performance was analyzed for different waterjet energy parameters (water pressure and standoff distance; distance between the nozzle tip and surface of the specimen). The garnet abrasive was collected after each test case and tested for reusability by particle size standard: particles larger than 150 μm, using sieve tests analysis. The results revealed that the drilling performance improved with a higher water pressure and flow rate, whereas the reusability decreased by 26%. Operating costs were reduced by 34% when the abrasive was recycled. These findings are expected to be useful for optimizing the total cost and duration of rock drilling using abrasive waterjets.