An experimental study on the effect of rock properties on the production of fine materials by a conical pick.

Abstract

This study examines how rock properties affect the production of fines and chips during rock cutting, a crucial aspect of mechanized excavation science that dictates cutting efficiency and excavator performance. Small-scale linear cutting tests using a conical tool were conducted on thirteen rock specimens made up of sedimentary and metamorphic rocks. Unrelieved mode cutting depths ranged from 0.5 to 6 mm, with fines production quantified through sieve analysis. Mechanical properties, including uniaxial compressive strength (UCS), significantly affected fines: the greater the UCS, the lower the fines due to microcrack extension. At greater strengths and cutting depths, however, the force to break rock resistance enlarged the crushed zone, sometimes contributing to an enhancement in fines production. Also, among the physical properties of rocks, an increase in density and a decrease in porosity lead to a reduction in fine grains, greater rock compaction, and an increase in the amount of chips. Microscopic properties indicated texture coefficient to be the most influential factor, with greater texture coefficient making the rock stronger and favoring crack propagation to the free surface to minimize fines. Shape factor was the least contributing factor. The study shows how rock properties control cutting behavior, giving insight into the optimization of excavation performance through a better understanding of fines, chips, and crack growth mechanisms.