Mining Project: Alternative Mining Methods in Challenging Environments

Research Summary

The purpose of this project was to reduce the injuries and fatalities caused by stress-induced ground failures in underground metal mines by developing an integrated, systematic approach for monitoring mining-induced seismic events, evaluating their hazard potential, and mitigating their effect on the stability of underground workings. Alternative mining methods were also investigated as a means of reducing stress concentrations and removing workers from hazardous areas. Collaborative research was conducted with four underground metal mines located in the western U.S., two universities, and multiple industry experts.

In conjunction with this research, comprehensive backfill design guideline development was advanced for the use of cemented paste backfill in rockburst-prone ground conditions and for the use of cemented rockfill in weak ground conditions. Information and standard practices from the concrete industry, soil mechanics, and rock mechanics were combined along with new developments in geotechnical instrumentation and laboratory testing to develop comprehensive guidelines for the design and use of cemented backfill as ground support in conjunction with underhand cut-and-fill mining methods.

This project had four primary research aims:

(1) Develop calibrated ground response models and site-specific hazard models using geologic data, mining induced seismic data, and instrumentation.

(2) Integrate seismic monitoring and instrumentation data with numerical modeling to evaluate the potential for alternative and automated mining methods to reduce worker exposure to high-stress areas where rockbursts are a major hazard.

(3) Develop cemented backfill design guidelines based on methodical lab testing, empirical design, and instrumentation results, as well as establish industry standards for cemented backfill quality control programs, handling, and emplacement.

(4) Evaluate the success of alternative mining methods using automated mining equipment in various challenging ground conditions to reduce the exposure of workers to ground hazards, particularly in high-stress areas. This work will be continued in a follow-on project, "Managing Ground Support for Long-Term Stability in Underground Mines."

The major outputs from this project are peer-reviewed, publicly available publications presenting the elements of the rock mechanics, seismology, ground support, backfill, and mine design aspects of this research. Application of research results at collaborating mines led to improved rockburst control practices, backfill design methods, and ground control safety, which in turn promoted a more widespread adoption of these innovations. The remaining gaps in this research will be addressed in a follow-on project, "Managing Ground Support for Long-Term Stability in Underground Mines."

This research supports the NIOSH mission of improving the health and safety of mine workers by specifically addressing the NIOSH Strategic Plan Strategic Goal 2, "Reduce mine workers' risk of traumatic injuries and fatalities," through the adoption and assessment of design procedures and workplace solutions to reduce ground control-related injuries.