Discrete Element Modeling of the Effects of Cutting Parameters and Rock Properties on Rock Fragmentation

Jiuqun Zou,Jihuan Han,Weihao Yang

doi:10.1109/access.2020.3011709

Abstract

Rock properties (e.g., brittleness, fracture toughness, hardness, compressive strength and tensile strength), cutting parameters (e.g., cutting depth, attack angle, wedge angle, cutting velocity) and confining stress are closely related to rock fragmentation behaviors in the design and application of excavation and mining machinery. To investigate the influence mechanism of those factors on rock fragmentation, a series of linear cutting numerical tests were conducted using the discrete element method. Numerical models with different rock mechanical parameters were calibrated by changing the cohesion strength-to-tensile strength ratio of the linear parallel bond model in PFC2D. The effects of cutting parameters on rock fragmentation were studied using orthogonal test and range analysis. The numerical results indicated that the strength ratio had a dominant effect on the specific energy and that the cutting depth and attack angle had a dominant effect on the mean cutting force. The cutting velocity significantly influenced the specific energy, and a higher cutting velocity should be adopted in actual rock cutting. In addition, a cutting force prediction model was proposed that considered factors such as the compressive strength, wedge angle, attack angle and cutting depth. Moreover, the introduction of more rock mechanical parameters into the evaluation indicators can reflect a greater number of fragmentation characteristics.

Highlights

As the exploitation of resources intensifies, mechanized rock drilling and cutting are widely used for deep underground rock excavation and mining engineering
Bilgin [2] studied the rock properties that affect the performance of conical picks through cutting tests and found that the uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) exhibited the best correlations with cutting forces and specific energy (SE) consumption
The main failure patterns all changed from compression-shear failure to tensile failure

Summary

Introduction

As the exploitation of resources intensifies, mechanized rock drilling and cutting are widely used for deep underground rock excavation and mining engineering. Bilgin [2] studied the rock properties that affect the performance of conical picks through cutting tests and found that the uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) exhibited the best correlations with cutting forces and specific energy (SE) (i.e., the energy required to cut a unit volume of rock) consumption. Balci [3] found that using only strength data for cutter force prediction was not very accurate in rock cutting tests of three different types of rock with nearly. Hurt [6] tested conical picks with wedge angles of 76, 80 and 90◦ at a 45◦ attack angle, and they found that the yield of the rock was independent of the attack angle (between 40 and 55◦) and that the cutting force was clearly affected by the wedge angle.

Methods

Results

Conclusion