Physical modeling of joints spacing effects on penetration rate of rotary drilling in open pit mines

Drilling is one of the most expensive stages of open pit mining and has many complexities. In drilling process, many parameters interact simultaneously each other, where studying each parameter requires recognition of the effects of other characteristics of rock mass and its material. In this paper, the main aim has been directed to investigate the effects of joint spacing among the structural parameters of rock mass. For this purpose, in order to study the condition of drilling in jointed rocks with different spacings, jointed rock masses with spacing of 10, 20, 30, 50 and 100 centimeters physically were modeled in laboratory by using cemented blocks. Penetration rate of cross bit has been measured by using rotary drilling system. According to the numerical results obtained from experiments, by increasing of joints spacing, penetration rate (m/min) of drill bit in jointed rock masses increases logarithmically.