Rock excavation using abrasive waterjet

Abstract

Highly developed metropolitan cities demand underground space for the effective use of limited land. Ground vibration induced by construction blasting processes can cause serious problems in the vicinity of the construction sites when large underground structures such as transportation tunnels are constructed in urban areas. Abrasive waterjet technology can be applied in the cutting of hard rock cutting as it offers two principle advantages: high versatility and no mechanical stress generated. Thus, an abrasive waterjet can be very useful to excavate rock in mining or civil engineering projects. Understanding the parameter effects on the cutting performance of an abrasive waterjet is very important because optimized parameters can increase the erosion efficiency. Rock specimens are cut with different energy and geometry parameter combinations to evaluate the parameter effects. Material parameter effects are analyzed based on the uniaxial compressive strength, which is one of representative physical properties in rock excavation design. Furthermore, the relationships between the cutting depth (and volume) and the effective parameters are explored to provide an economic design of the parameters. The cutting depth is an important index with which to estimate the excavation time and cost, but it is very difficult to predict because there are various effective variables to consider, such as the energy, geometry, and material parameters. The cutting depth is expressed in terms of the energy and geometry parameters based on the maximum kinetic energy, which is correlated with the cutting depth in terms of the empirical constant (α) and exponent (β). The maximum kinetic energy ? cutting depth model is verified using experimental cutting data for hard granite with water pressure, traverse speed, standoff distance, and waterjet system (i.e., the intensifier type and the plunger type). The developed model provides valuable insight into the relationship between the ...