Investigation of Fracture Damage and Breaking Energy Consumption of Hard Rock Repeatedly Cut by Abrasive Water Jet

Abrasive water jet is widely used in the field of deep hard rock cutting. To accurately and quantitatively evaluate the implementation effect of repeated cutting hard rock by jet, the ratio of the jet cutting speed to the cutting times is defined as an index to evaluate the rock-breaking effect and efficiency, and laboratory experiments of repeated cutting granite by abrasive water jet under different horizontal stress are carried out. The obtained results show that the increase of rock horizontal stress leads to a rougher cutting surface of the abrasive jet, the average growth rate of roughness is 34.8 and 15.8%, respectively, and increases the specific energy consumption rate of the rock breaking, the average growth rate of specific energy consumption is 11.8 and 38.9%, respectively. When the repeated cutting method is used to break rock, as the ratio of the cutting speed to the cutting times increases, the cutting surface roughness and the specific energy consumption of rock breaking decrease first and then increase. When the cutting speed is 9 mm/s and the cutting is repeated for 3 times, the breaking effect and efficiency are the best. Under the combined action of axial high-speed impact, radial rotary grinding, and water wedge cracking, the local mineral particles in the slot may undergo trans-granular or inter-granular fracture, which eventually evolves into spalling and macro-damage of mineral particles. Highlights The variation of geometric parameters of slot cut by abrasive water jet with different horizontal stress and repeated cutting times is analyzed. The surface roughness changes after repeated jet cutting were analyzed using three-dimensional morphological scanning. The micro morphological characteristics of the slot surface under repeated cutting by abrasive water jet are described. The results could provide theoretical basis and production guidance for hydraulic cutting and breaking of deep hard rock.