Mining Program Area: Ground Control
The ground control program aims to improve the state of the art in ground control practices in U.S. mines through research, dissemination, and training. It seeks to advance the understanding of potential ground control hazards and improve worker safety by reducing the occurrence of rock falls.
In 2002–2011, an average of 6 fatalities and 520 injuries related to ground control in underground coal mines occurred per year. Ground falls remain the highest single cause of fatalities and injuries in underground coal mines. Metal/nonmetal mines had an average of 2 fatalities and over 200 injuries related to ground control failures in the past 5 years. Ground control research and worker training could lead to a reduction of these injuries and fatalities.
In addition to the statistics, mining keeps evolving, and the potential ground control related hazards need to be evaluated, addressed, and appropriately controlled. The ability to adjust practices and knowledge as the mining methods evolve is essential to ensuring that mine worker health and safety continues to improve.
The ground control program works to answer the following questions: How can pillar and support designs be improved to eliminate rock fall hazards in mining? What are the signs of rib instability, and what are the best practices and designs to eliminate this hazard? What are the causal factors of roof falls, and how can they be identified before, during, and after mining? What can be done to reduce roof falls to improve worker safety? How can supports be designed to accommodate new production requirements and mine designs?
The Office of Mine Safety and Health Research (OMSHR) is the primary mining research institute in the United States, and it supports the majority of the other U.S. organizations performing research in ground control safety. OMSHR has an exceptional mix of researchers with theoretical and practical expertise in ground control to provide a deep insight into the issues and potential solutions for improving ground stability conditions in underground mines. OMSHR also has a unique testing machine for evaluating and testing standing supports. These tests give the mining industry information for both established and prototype support designs for improved gateroad stability in a wide range of ground conditions. This facility is the only one of its kind in the United States and has capabilities not found anywhere in the world.
Currently OMSHR has a mix of internal projects, external contracts, and collaborative research ventures. While OMSHR's internal expertise is fairly expansive, the specific focus and differing viewpoints of its external contracts and collaborators provide an opportunity to accomplish OMSHR's mission in a timely fashion. Additionally, the external contracts are an avenue to advance the industry expertise in ground control and add additional researchers to complete relevant research that OMSHR does not have the capacity to perform currently.
Numerous software programs have been developed to give the industry guidelines and tools for both mine design and support design to reduce ground instability. These include Analysis of Longwall Pillar Stability (ALPS) and Analysis of Retreat Mining Pillar Stability (ARMPS), which are required by the Mine Safety and Health Administration (MSHA) for underground coal mines. Most recently, a program called S-Pillar was developed for stones mines; it provides design guidance for entry and pillar sizes to prevent collapses. A new methodology has been proposed for evaluating and designing rock bolts for support in coal mine roofs. Tools were recently developed to evaluate shotcrete flexural strength, adhesion, and early strength.