13
Review of Ground Failure Prevention Research

Key Findings and Recommendations for Ground Failure Prevention Research

  • Research is in high-priority areas, has resulted in new knowledge, and is connected to improvement in workplace protection.

  • The Mining Program should be involved in developing better methods of periodic or continuous monitoring of slope movement by evaluating recent advances in radar, photogrammetric, and other methods.

  • Future ground failure prevention research should include research into unwanted consequences of blast-weakened materials.

  • Research is needed to minimize risk to underground workers and potential damage to surface structures associated with mining-induced seismicity.

  • The Mining Program should consider ways to improve sophisticated numerical techniques for modeling variously shaped openings in heterogeneous and discontinuous materials at different degrees of saturation.

  • The Mining Program should be involved in developing best strategies for deep mining (>600 m).

STRATEGIC GOALS AND OBJECTIVES

With a few exceptions, ground failure prevention research within the Mining Program is limited to the reaction of the perimeter of excavations in the earth’s crust. Such excavations are produced in the mining of coal, metal and nonmetal, and aggregate and can be underground or on the surface.

Mining has the highest fatal injury rate of any U.S. industry, and ground failures are a significant cause of those injuries and deaths (NIOSH, 2005a). The reduction of ground failure fatalities and injuries is one of the National Institute for Occupational Safety and Health (NIOSH) Mining Program’s strategic goals. The performance measures of success for this goal are “(1) mine fatalities by ground



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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health 13 Review of Ground Failure Prevention Research Key Findings and Recommendations for Ground Failure Prevention Research Research is in high-priority areas, has resulted in new knowledge, and is connected to improvement in workplace protection. The Mining Program should be involved in developing better methods of periodic or continuous monitoring of slope movement by evaluating recent advances in radar, photogrammetric, and other methods. Future ground failure prevention research should include research into unwanted consequences of blast-weakened materials. Research is needed to minimize risk to underground workers and potential damage to surface structures associated with mining-induced seismicity. The Mining Program should consider ways to improve sophisticated numerical techniques for modeling variously shaped openings in heterogeneous and discontinuous materials at different degrees of saturation. The Mining Program should be involved in developing best strategies for deep mining (>600 m). STRATEGIC GOALS AND OBJECTIVES With a few exceptions, ground failure prevention research within the Mining Program is limited to the reaction of the perimeter of excavations in the earth’s crust. Such excavations are produced in the mining of coal, metal and nonmetal, and aggregate and can be underground or on the surface. Mining has the highest fatal injury rate of any U.S. industry, and ground failures are a significant cause of those injuries and deaths (NIOSH, 2005a). The reduction of ground failure fatalities and injuries is one of the National Institute for Occupational Safety and Health (NIOSH) Mining Program’s strategic goals. The performance measures of success for this goal are “(1) mine fatalities by ground

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health failures are reduced by 50% within 8 years, (2) injuries by ground and roof support system failures are reduced by 25% within 5 years and by 50% within 8 years, and (3) unplanned roof falls are reduced by 20% within 5 years and by 40% within 8 years” (NIOSH, 2005a). Table 13-1 summarizes the mining program’s intermediate goals and their performance measures in this research area and provides committee comments regarding their appropriateness. In the opinion of the committee, Mining Program research in this area is innovative in both establishing intermediate goals and formulating research methodologies. Although some of the issues in Table 3-4 are not currently being addressed by the Mining Program, the intermediate goals and current Mining Program research projects all closely relate to issues the committee assessed as most relevant (see Chapter 3). Improvement is needed in broadening the intermediate goal statements. In some cases, the intermediate goal is too restrictive. Very specific performance measures facilitate assessment, but broadening the intermediate goals would clarify the relevance of complementary efforts. The intermediate goals established for ground failure prevention research are forward looking and focused appropriately on emerging safety issues. REVIEW OF INPUTS Table 13-2 summarizes MSHA fatality statistics as a measure of relative frequency of accident types for coal and metal or nonmetal mining. The data indicate ground control conditions contribute significantly to fatalities in coal mining and, to a lesser extent, in metal and nonmetal mining. Ground failure fatalities range from 11 to 52 percent of the total number of coal mining fatalities per year, with an average of about 29 percent between 1997 and 2005. The number of similar fatalities for the same period in the metal and nonmetal sectors ranged from 0 to 13 percent per year. The data support the concern that ground failures represent a significant cause of injuries and fatalities and can be a burdensome mine operating cost. The committee concludes that Mining Program personnel are working with metal-nonmetal and coal mine personnel to identify areas of greatest concern. Current and planned research deals with issues raised by stakeholders particularly in the areas of monitoring highwalls and slopes in surface mines, avoiding inundations when mining is close to water impounding structures and abandoned mines, surface treatments to improve long-term stability of underground openings, monitoring roof conditions in underground stone mines, and reducing damage caused by conventional blasting, to mention only a few examples. The program needs to, however, prepare itself for attrition. Because many seasoned Mining Program

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 13-1 Intermediate Goals and Performance Measures of Ground Failure Prevention Research and Committee Comments Intermediate Goala Performance Measurea Committee Comments 1. Improve understanding of rock mass failure mechanics Models will be developed and applied to explain the coal mine entry and caving-overburden response (3-year time frame) and the failure modes caused by horizontal stresses in stone mines (4 years). Additionally, the models and related knowledge (including appropriate design and intervention approaches) are transferred to the industry within 6 years By limiting the types of mining investigated and the geologic environments of study, as has been done, the intermediate goal is achievable. Much more work is needed to expand the intermediate goal to the mining industry as a whole. 2. Develop better roof surface control technology Number of rock fall injuries in coal mines will be reduced by 50% over the next 5 years Intermediate goal is aggressive, and training and monitoring need to be integral to the technology. No logical basis for selecting 50% as the target. The performance measure should be a sustained decreasing trend in rock fall injuries 3. Develop better design-based control technology for multiple-seam coal mines (1) Multiple-seam design guidelines will be provided to the mining industry within 3 years, and (2) severe multiple-seam interactions will be reduced by 80% within 8 years Smaller mines may not be able to utilize developed technologies that are design-based, even if available within the time frames. No logical basis for selecting 80% as the target. The performance measure should be a sustained decreasing trend in accidents resulting from multiple-seam interactions 4. Develop new ground control technology for mines with low-strength roofs Ground control technologies are adopted by the target mine population, resulting in a 50% reduction in roof falls at these mines. Technologies will be applicable to the estimated 25% of U.S. coal mines that encounter weak roof conditions Intermediate goal is too restrictive. Problems with weak roofs occur in mines other than those in the Illinois and northern Appalachian coal basins

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health 5. Improve selection of best support systems for specific geologic environments (1) Characterize 15 new standing supports over the next 5 years, and develop more efficient standing support systems that are implemented in the mining industry; and (2) new decision logic for support selection and implementation is adopted by large segments of the mining industry Manufacturers are cooperating, as are mining companies, making achievement of this intermediate goal likely 6. Develop a sensor-based risk management systems for roof falls in stone mines Sensor-based risk management system for roof falls will be developed and used in 20% of underground stone mines within 4 years Funding and time constraints within the industry may hinder sustained reduction of roof fall accidents 7. Reduce injuries caused by rock bursts Developed ground control technologies are adopted by 50% of the target mine population Mining companies are enthusiastically adopting these technologies, resulting in substantial safety improvement. The intermediate goal is likely to be achieved. Additional work is needed to reduce coal burst accidents in underground longwall operations aSOURCE: NIOSH, 2005a.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 13-2 Coal and Metal or Nonmetal Mining Fatalities Related to Ground Failure   Roof Fall Rib or Face Fall Highwall Failure Loose Rock Highwall Stockpile Slide Total Fatalities Percentage of All Mining-Related Fatalities Year Coal M/NM Coal M/NM Coal M/NM Coal M/NM Coal M/NM Coal M/NM Coal M/NM 1997 5 2 3 1 0 2 0 0 0 0 30 61 27 8 1998 13 2 1 1 1 0 0 0 0 0 29 50 52 6 1999 10 3 3 2 3 2 0 0 0 0 34 53 47 13 2000 3 0 1 1 1 1 0 0 0 0 38 48 18 4 2001 9 4 2 0 0 0 0 0 0 0 42 30 26 13 2002 5 0 2 0 0 1 1 0 0 0 27 42 30 2 2003 2 0 1 0 0 0 0 0 0 0 28 26 11 0 2004 3 0 2 0 0 1 0 0 1 0 28 27 21 4 2005 9 0 0 0 0 0 0 0 0 0 22 35 41 0 Cum 59 11 15 5 5 7 1 0 1 0 278 372 29 6 NOTE: M/NM = metal and nonmetal. SOURCE: http://www.msha.gov/fatals/fab.htm [accessed March 13, 2007].

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health researchers in ground failure prevention are approaching retirement age, the development of junior-level personnel should be accelerated to maintain momentum. REVIEW OF ACTIVITIES There are 11 ongoing research projects in the area of ground failure prevention research (NIOSH, 2005a), briefly summarized and evaluated in Table 13-3. The intermediate goals referred to in this table are consistent with those in Table 13-1. Identifying projects 2 and 10 on Table 13-3 as “complementary” to intermediate goals should not relegate them to a less important status than other projects. The committee considers the activities in ground failure prevention research to be highly relevant. Two efforts deserving special recognition are activities associated with the mine roof simulator and rock burst research. The simulator has also been a critical resource in testing new roof support ideas and has resulted in accelerated commercial development of more than 40 new roof support technologies over the past 5 years. Seismic monitoring and basic research into strategies to reduce bursting potential will continue to serve the mining industry in the future. Ground failure prevention project descriptions provided by the Mining Program (NIOSH, 2005a) often contain clear reference to the stakeholder group to whom the efforts apply (e.g., projects 4 and 8 in Table 13-3). The project scopes are broad enough to avoid being considered consulting projects for individual mines, but narrow enough to focus on specific issues. It is not clear, however, how these issues fit into a coordinated research agenda. It may be possible to have a more general project scope that would include two or more applications with greater efficiency in effort and resources. REVIEW OF RESEARCH OUTPUTS AND TRANSFER ACTIVITIES Table 13-4 summarizes the types of outputs generated through ground failure prevention research in the Mining Program. Ground failure prevention output represents approximately 24 percent of the total Mining Program output during the period evaluated. Publications are the primary form of output and include both peer-reviewed journal articles and conference proceedings. The emphasis on publishing research results in the refereed literature provides opportunities for professionals in the field to review and evaluate the work of the Mining Program. Furthermore, the Mining Program has utilized current technology to transfer results through electronic media and print. Peer review of publications helps ensure the quality of research, but conference articles and proceedings generally reach end users more quickly. Several symposiums and meetings are held on an annual basis by professional organizations and

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 13-3 Ground Failure Prevention Projects and Committee Assessment of Relevance and Impact Project Titlea Intermediate Goal Descriptiona Relevance Impact 1. Development and Evaluation of Innovative Roof Support Technologies 5 Testing various devices developed by support manufacturers using the Mining Program’s unique Mine Roof Simulator Highly relevant to improving workplace protection; the Mining Program is engaged in transfer activities Major contribution expected 2. Fragmentation Methods and Ground Control Safety Complementary to overall strategic goal Investigate blast patterns and rock damage caused by blasting High-priority area, but the Mining Program is not currently involved in transfer activities Activities are ongoing and likely to produce improvements 3. Fundamental Studies of Factors Responsible for Falls of Ground 6 Advancing understanding of ground falls and development of monitoring systems to detect the onset of instability High-priority area, and transfer activities have begun Microseismic monitoring likely to result in improvements; publications produced 4. Guidelines for Eliminating Hazardous Ground Conditions from Underground Stone Mines 6 Evaluation of field data to determine safe limits for roof spans and pillar dimensions and the effect of mine air temperature and humidity on pillar performance Highly relevant to improving workplace protection. The Mining Program is engaged in transfer activities Results have produced safer designs. Positive impact expected in the workplace 5. Ground Stability Through Advanced Mine Design 1, 3, 5 (indirectly) Deep-cover coal pillar recovery, high horizontal stress control, and multiple-seam mining Highly relevant to improving workplace protection; the Mining Program is engaged in transfer activities Statistics show a reduction in fatalities

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health 6. Identification and Control of Rock Burst Hazards 7 Wall strain, electromagnetic emissions, and microseismicity are being investigated to determine if they can be used to identify rock burst failure mechanisms and warn of impending failure Highly relevant to improving workplace protection, and the Mining Program has been engaged in transfer activities. Research should be expanded to include bumps in deep coal mining (a more pressing problem in the future) Past and current work has resulted in reduction in injuries and fatalities 7. Preventing Injuries from Falling Rock in Underground Coal Mines 2 Development of surface treatments, specifically application of screens, along with methods of avoiding injury caused by installation of screens, and identification of geologic materials that deteriorate with time Relevant and directly related to improvements in workplace safety Publications produced, likely to improve workplace safety 8. Reduction of Groundfall Hazards in Nevada 2, with overlap in 1 and 4b Mine design criteria including rock mass ratings and span widths and the use of fiber-reinforced shotcrete as a surface treatment to improve stability Highly relevant to improving workplace protection; the Mining Program has engaged in transfer activities Design manual adopted by mines in four states 9. Roof Fall Evaluation and Mediation in Weak Rocks 4b How roof supports perform in weak rock, how fracturing is induced by excavation, and how fracturing can be arrested High priority in developing improved analytical design techniques for underground mines Hardware developed now being deployed 10. Slope Stability Hazard Recognition Complementary to overall strategic goal Improve safety near slopes in surface mines and near openings in large underground mines Identified as relevant by stakeholders Publications produced, computer program developed, and video produced. New monitoring equipment could substantially improve workplace safety

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health Project Titlea Intermediate Goal Descriptiona Relevance Impact 11. Stability Assessment with Seismic Monitoring 7 Better awareness of unusual ground response to mining and forensic analysis of major ground movement Highly relevant, likely to result in better understanding of potential damage to surface structures Assistance is now being provided to Colorado mines aSOURCE: NIOSH, 2005a. bIntermediate goal 4 was developed specifically for the Illinois and northern Appalachian coal basin, but projects may have wider range of application.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 13-4 Summary of Ground Failure Prevention Outputs (1998-2005) Year Publications (peer reviewed and conference proceedings) Patents Software Workshops and Training Web Video Total 1996 46 1 0 0 0 0 47 1997 36 0 0 5 1 0 42 1998 37 0 0 5 0 0 42 1999 35 0 0 5 0 1 41 2000 27 0 3 7 1 1 39 2001 49 2 0 5 1 1 58 2002 28 1 0 3 1 1 34 2003 35 0 3 4 1 0 43 2004 33 0 3 4 0 2 42 2005 30 1 2 1 0 0 34 Total 356 5 11 39 5 6 422 SOURCE: NIOSH, 2005a. technical interest groups on such topics as ventilation, ground failure prevention, longwall mining, health and safety, and miner training. In the experience of the committee, mining practitioners generally seek out these conferences and workshops in preference to peer-reviewed journals. The ratio of conference articles to well-recognized proceedings and peer-reviewed publications is about 2:1, which is reasonable given the makeup of stakeholders. The Mining Program is to be complimented for encouraging and supporting travel to national meetings to present research results. According to the Mining Program Briefing Book, ground failure prevention research receives approximately 16 percent of the total program budget but has produced nearly 24 percent of the outputs. The ground failure prevention portion of the mining program discretionary budget is approximately 10 percent. These statistics indicate good productivity. The Mining Program has done an admirable job of improving technology transfer and making ground failure prevention research results available on electronic media. REVIEW OF INTERMEDIATE OUTCOMES AND CAUSAL IMPACT Defined deliverables or outputs resulting from research efforts have intrinsic value, but only to the extent that they are translated into practice. Table 13-5 relates outputs of the ground failure prevention research group to specific intermediate outcomes observed from 1996 to 2005.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health TABLE 13-5 Outputs and Intermediate Outcomes Related to Ground Failure Prevention Research Outcomes Output Description Related Intermediate Goal Intermediate Outcome Coal Mine Roof Rating (CMRR) System and software package (2000) Methodology and procedure for characterizing mine roof materials 1 The Mining Program developed ground control design tools based on CMRR. CMRR accepted as a standard in the United States and other countries Published descriptions of horizontal stress concentrations in longwall headgates and methods to prevent failure; Analysis of Horizontal Stress Effects in Mines (AHSEM) software (2001) Control of horizontal stress in mining to reduce injuries and fatalities 1 Wide circulation of publications, Mining Program development of software, Mining Program-developed control technologies widely used in the mining community. Major headgate failures largely eliminated in longwall mines Design charts for selecting applicable web and barrier pillar widths; Analysis of Retreat Mining Pillar Stability (ARMPS) computer program (2003) Design guidelines for safe highwall mining systems, pillar recovery Indirectly related to 5 Several leading companies routinely use ARMPS or new design charts for highwall mining. ARMPS incorporated into guidelines for mine design to avoid massive pillar collapses Promotion of roof fall forecasting techniques in stone mining sector Mitigating ground fall hazards in underground stone mines 6 Project is ongoing; monitoring activities at more mine sites than in past years; new mine layouts implemented at several sites Hardware and computer logic for Mobile Roof Support (MRS) warning systems and guidelines for safe use MRS for retreat room-and-pillar mines 4 Technology incorporated into MRS system design by a major commercial manufacturer. Currently used in 34 coal mines Support Technology Optimization Program (STOP) (2004) Decision making for selection and placement of mine roof supports 5 Approximately 1,000 copies of software distributed. Used internationally

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health Analysis of Longwall Pillar Stability (ALPS) computer program Statistical analysis of mining case histories to provide design guidelines for safe pillar design, roof support, and tailgates 4 ALPS, in combination with STOP, is industry standard for longwall pillar and support design in the United States. A derivative product is used in Australia. Used extensively by the Mine Safety and Health Administration (MSHA) and state regulatory agencies, and part of the curriculum in at least four mining schools Personal bolter screen (PBS) (2003); Make It Safer with Roof Screen video (2004) Reducing rock fall injuries to coal miners 2 Ongoing effort. PBS available through two roof support manufactures; more than 200 copies of the video requested 31 technical papers and presentations Rock burst control in deep mines using overhand mining methods and seismic monitoring 7 Ongoing and long-term effort. Adoption of Mining Program-recommended measures in some rockburst-prone mines SOURCE: NIOSH, 2005a.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health Most, if not all, of the intermediate outcomes listed in Table 13-5 relate directly to achieving the strategic and intermediate goals of this research area. The intermediate outcomes address issues identified by the committee and are consistent with the goals of the “idealized” ground failure prevention research program summarized in Table 3-4. Consequently, the intermediate outcomes are well focused and address subjects of the highest priority, thus justifying a high rating in relevance. The Mining Program lists 12 potential intermediate outcomes designed to reduce accidents associated with ground falls in the next 5 to 10 years (NIOSH, 2005a). Performance standards for these outcomes have been stated in terms of percentage reduction of fatalities and injuries. Because of overlapping contributions of regulatory agencies, industry safety programs, labor initiatives, and advancements from academia, it will be very difficult to quantify the contribution of the Mining Program to any future reduction in the number of accidents. It is better, therefore, to establish specific measurable goals for each current or future intermediate outcome. This has been done primarily in terms of planned publications and workshops, whose contributions in meeting the strategic goal may never be quantitatively measurable but are almost certainly to be of value overall. The Mining Program has identified the following research that will continue into the future: Improved highwall stability to reduce surface mine hazards. This effort is a continuation of current activities and focuses on concerns expressed by stakeholders. Potential outcomes are planned through 2005. The need for better methods of periodic or continuous monitoring of slope movement is a worthy effort. It does not clearly fit into any of the current intermediate goals; an intermediate goal appropriate for this topic should be established. Reducing injuries by improving shotcrete design criteria. Developing a set of design criteria for application of shotcrete as a means of rock support is a continuation of current efforts and clearly fits intermediate goals 2 and possibly 4. Research and field tests are warranted due to the prevalence of injuries and occasional fatalities caused by loose roof rock between primary supports. Outputs are planned through 2007. Improved pillar design in metal and industrial mineral mines to reduce ground control hazards. Recovery of pillars is commonly practiced in the national and international mining communities. Minimizing the size of support pillars in order to maximize resource recovery is a worthy goal as long as it can be done safely. This research is a logical extension of current work and is related to intermediate goal 6. Outputs are planned through 2009. A more general statement of goal 6 should clearly include this work.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health Avoiding inundation: developing guidelines for mining near bodies of water. Mining-induced seismicity (MIS) occurs in coal, metal, and nonmetal underground mining. MIS is a serious, potentially high-consequence event that can result in injuries to underground miners and possible failure of water-impounding surface structures. Failure of surface structures is a major concern for several western coal operations. Related research is currently being done by the Mining Program, and this is a worthy topic for future research. Outputs are planned through 2009. The effort is related to intermediate goal 7, but a more general goal should be established that clearly includes this effort. Improved mine safety through optimized extraction. The extent of damage in the perimeter of mine openings created by conventional blasting is poorly understood. Such damage is acknowledged as a primary cause of loose rock in underground roofs and ribs and on surface mine slopes. Fundamental research is needed to establish more effective guidelines for blasting practices that focus on reducing collateral damage. Research in this area can contribute substantially to achieving the strategic goal. This is an extension of current research and outputs are planned through 2007, but there is no clear statement covering this effort in the list of intermediate goals. Multiple-seam mining design guidelines. Recent work in this area was reported as part of the Mining Program’s intermediate outcomes. The list of intermediate goals clearly indicates this as an important contribution to achieving the strategic goal. A large number of underground coal mines are currently, or will be in the near future, dealing with multiple-seam mining. It is therefore, a worthy topic for Mining Program research, and outputs in the form of publications, software, and workshops are planned through 2008. Design of mine ventilation stoppings. Current mining law requires that stoppings withstand a transverse load of at least 39 pounds per square foot (psf). Air blast resulting from roof falls or mine explosions can produce overpressure in excess of 39 psf resulting in failure of the stoppings. Failure can precipitate more widespread consequences in the form of pollution of the mine atmosphere with toxic gases and/or catastrophic explosions and fires. With the recent fatalities at the Sago mine, there is no question that this could be a high-priority topic for the Mining Program. It is unclear, however, why the design of stoppings is included under ground failure prevention. Perhaps it would more logically be included under mine disasters. No ground failure prevention intermediate goal is clearly related to this topic. Roof span and pillar layout guidelines for stone mines. This effort is a continuation of current research with promising future outcomes. It is closely related to intermediate goals 6 and possibly 5. A large number of underground limestone mines in this country rely heavily on past practice for roof spans and pillar layout.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health An analysis of practice coupled with numerical modeling is a worthy focus for research, and outputs are planned through 2008. Reducing ground fall hazards in coal mines with low-strength roofs. Investigating the exacerbating influence of low-strength roofs is the subject of current research. As previously mentioned, this effort deals with problems in a specific geographic region. Involvement of industry partners certainly justifies the planned 4-year effort and planned outputs through 2009. The research clearly falls under intermediate goal 4. It is not clear how the outcomes of this research can be measured quantitatively, but it should play a significant role in reducing injuries in the applicable underground environment. Highwall mining stability guidelines. Outcomes resulting from this project have been described above. Two mining companies and consultants use the results of this study, and additional outcomes are planned in the form of modified software and workshops in 2006. These efforts will likely contribute to achieving the strategic goal, but there is no clearly stated intermediate goal covering this research program. Increasing roof fall forecast times with sensor-based monitoring techniques. Increasing fundamental knowledge of how roof falls behave and the development of warning systems are extensions of current research described above. This effort clearly falls under intermediate goal 6, and additional publications are planned in the coming 2 years. Reducing ground fall hazards in metal mines with weak rock. Ground fall in metal mines in Nevada, Idaho, and Montana is the focus of this work started in 2002. Outputs in the form of publications and presentations were planned through 2005. The decrease in injuries resulting from ground fall for the period 2000-2004 relative to 1995-1999 is significant especially in view of the recent increase in underground metal mine activity in these areas. Although the Mining Program’s contribution to this trend is not quantitative, it undoubtedly has improved mine safety. The effort is clearly related to intermediate goal 4. The committee heard from multiple industry representatives who expressed particular satisfaction with software available through the NIOSH web site and with videos that effectively present safety concepts. Videos, web pages, and publications available over the Internet demonstrate a commitment to provide output in electronic format as recommended in the National Research Council (NRC, 1995) review of the USBM. Stakeholders generally praised the ground failure prevention research in the Mining Program. Standards and guidelines have been adopted, both in the United States and abroad, based on output in this research area, and technologies have been implemented in the workplace.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health REVIEW OF END OUTCOMES There have been a substantial number of publications during the past 10 years, and of eight software packages have been produced during the past 3 to 4 years. The number of web-based downloads and the transfer of software in workshops and training sessions suggest that the software is now in the hands of industry practitioners. The extent to which this software is used in mine planning has not been measured objectively. However, the demand for short courses dealing with application of the software and the use of the software by the Mine Safety and Health Administration and state regulatory agencies indicate a high level of interest. The apparent decline in ground control fatalities over the past 10 years provides reason to believe this effort is having a positive impact. Pillar recovery in underground room-and-pillar coal mines has historically been a significant source of serious or fatal injuries due to miners advancing out beyond supported roof as coal pillars are recovered. The Mining Program has made significant advances in developing methodologies and practices for properly utilizing industry-developed Mobile Roof Support modules to provide temporary roof support to protect personnel. Mining Program guidelines for pillar recovery have been incorporated in Appalachian and Illinois Basin coal mines. The use of mobile roof supports is, or should be, standard practice for pillaring operations in all underground coal mines. The benefits have been well received in publications, manuals, and seminars. The efforts of the Mining Program, the former U.S. Bureau of Mines (USBM), and industry have contributed to a substantial reduction of injuries and fatalities in burst-prone mines. The statistics for ground fall fatality rates and ground fall incident rates show a downward trend over the past 10 years. It is not immediately clear how much of this favorable trend can be attributed to intervention by the Mining Program. Mining Program efforts very likely have played a significant role in improving mine safety. ASSESSMENT OF RELEVANCE AND IMPACT Most certainly, the efforts of the Mining Program have made at least a moderate contribution (as defined in the Framework Document, Appendix A) to end outcomes or well-accepted intermediate outcomes. The intermediate outcomes have resulted in new knowledge, and the Mining Program is actively engaged in transfer of this knowledge to the mining industry and regulatory authorities. Consequently, the Mining Program ground failure prevention effort justifies a high rating for impact.

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Mining Safety and Health Research at NIOSH: Reviews of Research Programs of the National Institute for Occupational Safety and Health As described earlier, the intermediate goals of ground failure prevention research address issues identified in the earlier NRC (1995) review of the USBM and deal specifically with critical areas identified by this committee in establishing a comprehensive ground failure prevention program. Research is in high-priority areas and is connected to improvement in workplace protection. Consequently, the Mining Program ground failure prevention program deserves a high rating for relevance. PROGRESS IN TARGETING NEW RESEARCH Ground failure prevention research is a heritage program, with future research needs identified primarily through concerns expressed by stakeholders and the prevalence of injuries caused by changing mining methods and geologic conditions. The Mining Program has identified several research areas it is pursuing. Examples of appropriately targeted new research include renewed work on highwall safety, improved strategies for multiple-seam mining, and blast damage control and surface treatment to minimize loose rock hazards. The Mining Program is also focusing on future research to reduce pillar and roof hazards in underground stone and industrial mineral operations in response to the projected demand for these commodities. Because of challenges posed by mining in increasingly severe geologic environments and in closer proximity to existing and abandoned mines, the Mining Program needs to expand its new research to include developing more robust numerical techniques for modeling mine openings in complex geologic materials; better void detection technologies; and strategies to improve design and safety in deep (>600 m) coal deposits.