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Rock Stability Research Could Make Mining Safer

A University of Arizona (UA) College of Engineering research program looking at new methods of determining rock strength could reduce hazardous working conditions that currently cause thousands of deaths every year in mining and construction.

Pinnaduwa H. S. W. "Kumar" Kulatilake, professor of geological engineering in the UA Department of Mining and Geological Engineering, is the sole principal investigator for a five-year project to develop new methods of assessing ground stability.

The National Institute for Occupational Safety and Health (NIOSH), which is part of the Centers for Disease Control and Prevention, is funding the research.

The true extent of mining fatalities globally is hard to gauge, but some estimates suggest that as many as 12,000 miners die every year in mine accidents. The primary cause of these fatalities is ground failure.

Ground Failure

Ground failure is generally any significant movement of the ground, such as a landslide or underground excavation collapse, or when ground moves and flows like a liquid, which results when earthquakes or high water pressure cause soil to lose its strength.

Tunnel or underground cavern collapse and catastrophic failure of slopes, dams and foundations are examples of ground failure encountered in mining and civil engineering projects. Part of the problem is that current methods of rock assessment are simply not up to the task of providing a detailed picture of what engineers are truly getting into when they start blasting and tunneling.

During the five-year project, Kulatilake will extend rock strength criteria he has developed to make them applicable in three-dimensions. He will be working with two mines in the U.S. and two mines in China to apply these new methodologies to underground and surface excavations to determine how well they work in the real world.

Kulatilake points out that it is not only miners who will benefit from being able to evaluate rock masses for potentially hazardous working conditions. "This is not only for mining," he said. "This work also relates to civil rock engineering projects such as tunnels, caverns, foundations, dams and slopes."

To develop new methods of ground stability analysis, Kulatilake will combine field investigations and extensive laboratory testing, such as CT scans and three-dimensional load testing, with three-dimensional numerical modeling, including new theoretical concepts and advanced statistical and probabilistic procedures to quantify variability and uncertainty.

Theoretical Models

His theoretical models will be made increasingly accurate over time as their predictions are validated using lab test results and field data. In essence, Kulatilake aims to bring more certainty to what is essentially educated guesswork when it comes to assessing ground stability.

"We have been using very simple methodologies in practice to address very complicated problems," he said.

MSHA Addresses Miner Discrimination Complaints

The Mine Safety and Health Administration filed 46 requests for temporary reinstatement during the 2012 calendar year, more than double any previous year, with the Federal Mine Safety and Health Review Commission on behalf of miners who submitted complaints of discrimination in the form of a suspension, layoff, discharge or other adverse action.

Additionally, the department filed 34 complaints alleging mine safety discrimination during 2012, also more than in any previous year.

The department filed 101 temporary reinstatement requests in calendar years 2009 - 2012, or an average of 34 per year, compared to an average of six per year 1993 - 2008. Additionally, the department filed a total of 105 discrimination complaints with the commission 2009 - 2012, compared to 63 during the prior four-year period.

According to Section 105(c) of the Federal Mine Safety and Health Act of 1977, a miner cannot be discharged, discriminated against or interfered with in the exercise of statutory rights because he or she has engaged in a protected activity such as filing a complaint alleging a health or safety violation, or refusing to work under unsafe or unhealthy conditions.