ABSTRACT:
In this paper, the finite element code, LS-DYNA 3D, was chosen as the simulation tool to study the rotary rock cutting process. By using an Automated Rotary Rock Cutting Simulator as the prototype, a numerical model of a continuous miner was developed. The rock grooves cut by the bits in the numerical model were used to investigate the rock ridge failure mechanism. The numerical study indicated that shear breakage acted as the dominant mechanism in ridge removal. Drum speed, depth of cut, and multiple bit interaction have minimal effects on the groove width. For a given bit pattern, Young’s modulus and Poisson’s ratio of the rock are two major parameters affecting the ridge removal.
1 INTRODUCTION
Rotary cutting machines, such as continuous miners and shears, are widely utilized in underground soft rock mining (e.g. coal mining and salt mining). These machines usually use cylinder-shaped cutting drums on which bits are laced based on certain patterns. During operation, the rotating drum sumps into the rock face with bits cutting the rock. Breakage of the rock ridges between the bits occurs when the bits hit the rock. Two contradictory theories exist to explain the mechanism of rock ridge breakage. One of the fundamental rock cutting theories was proposed by Evans (Evans et al. 1966), who considered the rock ridge breakage as tensile rock failure. This theory was utilized by other researchers to explain the general failure phenomenon of rocks (Whittaker et al. 1973, Roxborough 1973). On the other hand, Nishimatsu (1972) assumed shear strength of the rock is the dominant parameter governing rock failure. The numerical model used to simulate rotary rock cutting is first described in Section 2. Some numerical experiments and results are analyzed in Section 3. Conclusions drawn from the analysis are listed in the last section.
