Mining Project: Blast Damage Control to Reduce Injuries from Ground Falls in Underground Western U.S. Hard Rock Mines
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| Principal Investigator |
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| Start Date | 4/11/2016 |
| Objective | To make available an easy-to-use software tool that includes improved blast damage models that mining engineers can use in developing improved blast designs. The improved designs would include decoupling the perimeter holes and properly locating buffer holes to reduce perimeter damage. With this design guidance, it will be easier for engineers to implement controlled blasting methods. |
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Research Summary
Today, ground falls continue to be of major concern to miner safety. Risk exists at the drift face where the miner is responsible for drilling, blasting, rock scaling, and installing roof support. The proper design and execution of drifts will become even more important in the future as mines become deeper, rock mass/stress conditions grow more complex, mining scale increases, development rates are increased to improve profitability, and the demands for safe execution, safe operation, and minimum opening maintenance become ever greater.
The centerpiece of modern drifting is the drill jumbo, allowing the operator to drill complex patterns and to complete the drilling quickly and easily. Although drilling has improved, controlled blasting is not largely practiced in the mining community. Controlled blasting reduces perimeter damage, and less perimeter damage means lowered risk of ground falls, especially during scaling and installing roof support. A well-blasted drift requires less scaling time and less troublesome ground support installation. The reduced exposure time during these tasks reduces the risk of ground fall injury.
Rock blasting techniques in underground metal/nonmetal mines need to be optimized to minimize the extent of loose and/or damaged rock surrounding blasted openings. This optimization could significantly reduce mine worker exposure to ground fall hazards. Optimization techniques are design-based. In most underground mines, loose ground on the back/roof and ribs is removed by hand scaling or mechanical scaling. From a safety perspective, while scaling ultimately reduces the risks of rock fall injury to the mine workers, the personnel responsible for scaling are at risk for injury when performing this task. The longer it takes to scale and support damaged openings, the higher the potential risks to workers. Poor blast designs, poor quality control, or the presence of unknown geologic structures can lead to excessive overbreak and even cause damage to adjacent ground that has already been supported. This is a significant problem with respect to both mining safety and operational efficiency.
This project aims to provide industry and mine research institutions with detailed information on perimeter-controlled blasting and blast damage models that support perimeter control design. A blast design software tool will be completed in collaboration with the Colorado School of Mines to implement the software for user to input blast model parameters and visualize the damage extents in a specific design. Field application of the software tool will include monitoring a drifting process beginning with the expected design, implementation of drilling that design, the results of blasting examining the perimeter for loose rock, and finally examining the perimeter after ground support has been installed. Also, in collaboration with Hustrulid Mining Services, several blast damage models will be reviewed and included into a final report describing the technical aspects of the models, application for use in determining a practical damage radius, and input requirements for use in blast design.
A major outcome of this project will be a demonstration of the software documenting the use of the design tool and measuring the effect that explosives have on the perimeter and potential for loose rock. Drifting techniques at two mines will be investigated. Results will include the effect of blasting on perimeter control with presentation of the results at a mining conference.
Related NIOSH Publication
A new perimeter control blast design concept for underground metal/nonmetal drifting applications
Related Journal Articles
Modelling blast induced damage from a fully coupled explosive charge
Application of the NIOSH-modified Holmberg-Persson approach to perimeter blast design
Assessment and application of a single-charge blast test at the Kiruna Mine, Sweden
A case study examination of two blast rounds at a Nevada gold mine
Related Conference Papers
A gas pressure-based drift round blast design methodology
Design concept for perimeter control blasting in drifting operations
The extent of blast damage from a fully coupled explosive charge
Ground control and safety implications of blast damage in underground mines
A practical, yet technically sound, design procedure for pre-split blasts
Evaluation of Kiruna mine drifting data using the NIOSH design approach
Extent of damage associated with the passage of the compressive stress wave generated by blasting
Related NIOSH Contract Reports
Potential benefits of waterjet scaling in rapid tunneling systems
Waterjet scaling for reducing injuries in underground mining
- Page last reviewed: 1/6/2017
- Page last updated: 1/6/2017
- Content source: National Institute for Occupational Safety and Health, Mining Program