Ground Control Downloadable Mining Publications

Sixty years of rockbursting in the Coeur d'Alene district has taught painful lessons and led to a number of practical advances in controlling rockburst hazards. This paper summarizes those lessons, concentrating on practical measures that have been successfully adopted to reduce hazards. (PDF, 409 KB, 2002-02)

Stability analyses of fractured and faulted rock masses require delineation of the position, extent, and orientation of geologic discontinuities. Recommendations are made for increasing the accuracy and precision of locations of microseismic events detected under similar field conditions. (PDF, 4026 KB, 1992)

Evaluation of the "Advance and Relieve" mining method is described to determine effectiveness for conditions where high horizontal stresses caused long running roof falls resulting in hazardous conditions and the premature abandonment of panels. "Advance and Relieve" mining involves the removal of a pillar of a portion of a pillar during development, creating a cave along one side of the panel.  (PDF, 5767 KB, 2001)

As part of an on-going study at the Spokane Research Laboratory, several new methods for monitoring slope instabilities are being investigated. This paper describes the potential adaption of systems such as interferometric synthetic aperture radar, imaging spectroscopy, and time-domain reflectometry, to slope monitoring and design. (PDF, 654 KB, 1998)

A U.S. Bureau of Mines investigation of longwall panel layouts to maximize coal recovery and minimize interactive problems in multiple-seam operations. (PDF, 992 KB, 1992)

This paper summarises the results of a research project whose goal was to provide the Australian coal industry with a rib support design methodology and software tool that could be utilised by suitably qualified colliery staff. (PDF, 286 KB, 2005)

A case study is presented that relates statistical descriptions of joint sets to the distribution of local wedge failures along the crest of a catch bench at the Yellowstone Talc Mine. (PDF, 575 KB, 2004-05)

The objective of this is paper is to review the current state of knowledge and practice in highwall mining. (PDF, 1182 KB, 2005)
                                            

NIOSH completed a major study to identify the location and likely severity of multiple seam interactions (undermining and overmining). More than 300 multiple seam case histories were assembled into the largest data base of multiple seam case histories ever collected. These data were analyzed with the multivariate statistical technique of logistic regression, LaM2D to estimate the multiple seam stresses, ALPS and ARMPS to determine pillar stability factors, and the CMRR to measure roof quality. The study resulted in the development of a computer program, called Analysis of Multiple Seam Stability (AMSS), which can help mine planners to evaluate each potential interaction and take steps to reduce the risk of ground control failure.  (PDF, 658 KB, 2007)

As underground stone mining expands to deeper cover situations, and more efficient mining methods are utilized, effective stone pillar design methods become more important. Seventy-two stone-mine pillar designs were examined or factors effecting stability and results are presented. (PDF, 1315 KB, 1999-12)

Some of the issues discussed in this article include highwall stability, reasons for early pull out of highwall miner holes, and geotechnical engineering and planning factors and operating practices to improve highwall stability and minimize the risk of a trapped highwall miner. (PDF, 335 KB, 2004-08)

A state-of-the-art, three-dimensional, full waveform, microseismic system was used to analyze the rock failure around a deep bump-prone longwall panel. Analysis of the recorded events is discussed. (PDF, 442 KB, 2001-08)

A statistical study was conducted of roof bolt performance at a number of mines throughout the U.S. Analysis of the results led to guidelines that can be used to make preliminary estimates of the required bolt length, capacity, and pattern to improve roof stability for more difficult conditions. (PDF, 140 KB, 2001-08)

A study was conducted to determine the causes of slope failure and highwall/spoilbank failure and included: a review of accident statistics; a review of mining laws pertaining to surface mining; a literature review; and mine visits. The study emphasized surface mines in West Virginia, Ohio and Pennsylvania. (PDF, 248 KB, 2000-08)

A seismic monitoring system located at NIOSH's Lake Lynn Experimental Mine has monitored experimental gas and dust based explosions and impact tests. The results suggest a large explosion that's not restricted can generate potentially the same magnitude as a small explosion that is restricted. (PDF, 959 KB, 2008)

To provide a better understanding of the mechanics of strata deformation, the authors have collected and reviewed measurements of convergence and stress in one western U.S. mine and have completed pseudo-three-dimensional, boundary-element modeling for two typical pillar-pulling plans. (PDF, 202 KB, 1998)

Despite its potential importance, there is no widely accepted anchorage test for fully grouted roof bolts. Recent studies using short encapsulation pull tests are described. (PDF, 864 KB, 2002-08)

The objective of this study was to test the capability of ground penetrating radar to determine the extent of grout penetration into the mine roof strata in the 13-G room area of the NIOSH Safety Research Coal Mine. The study showed that GPR technology can be a useful tool for detecting changes in mine roof due to the injection of the grout. (PDF, 1051 KB, 2004-08)

This paper examines the effect of end conditions and load profiles on prop support performance and applies a new analysis methodology based on eccentric loading to determine a factor of safety for load capacity. Recommendations for installation practices that minimize eccentricity and therefore preserve capacity are also provided. (PDF, 304 KB, 2007)

An investigation of the hazards in and around ore passes in hard rock mines. Risk assessment methods, such as fault-tree analysis, have been employed to identify the most probable causes of ore-pass failures, define research priorities and analyze the factors that result in malfunctioning and unsafe ore passes. (PDF, 903 KB, 1997)

The Coal Mine Roof Rating (CMRR) has been widely accepted as a tool for geologic characterization and mine planning. The application of the CMRR to extended cuts (cuts greater that 6 m (20 ft) in length) is discussed. (PDF, 313 KB, 1999-04)

Several remote sensing technologies are being evaluated as tools to assess slope stability and monitor slopes for hazards. An interferometric radar device capable of detecting very small displacements on slopes has been assembled and tested. (PDF, 1440 KB, 2004)

This paper summarizes developments in the application of ground-based radar to slope stability monitoring and presents information on NIOSH-sponsored experiments recently completed. Field tests of a hyperspectral imager were conducted to assess its value for improving geologic maps of potentially unstable alteration zones on mine slopes (McHugh and others, 2001). Computerized monitoring methods using images from digital and video cameras are being assessed for application to mine slope surveillance. (PDF, 7065 KB, 2006-04)

The point estimation method is a computationally efficient approach for estimating the probability of sliding. This method expedites slope stability simulation routines used by NIOSH software to stochastically describe rock slope behavior and assist the engineer in designing catch benches for large rock slopes. Enhanced bench design translates into increased operational efficiency and safer working conditions in open pit mines and quarries. (PDF, 1713 KB, 2004)

Rock drilling parameters including thrust, rotational speed, torque and velocity were examined to determine the ability to identify the strength of the rocks being drilled from the measured parameters. (PDF, 724 KB, 2000)

This paper introduces various warning signs of slope instability so operators are better able to recognize hazards. The most common slope monitoring equipment and practical methods of installation are discussed as well as the limitations of these systems. (PDF, 413 KB, 2001-08)

A methodology to assess the risk for a roof fall is proposed in a preliminary fashion based on engineering judgment acquired from extensive underground stone mine experience and examination of related literature. The proposed method uses an observational technique to identify the risk of roof falls in three categories. (PDF, 201 KB, 2006-03-27)

This paper describes research designed to quantify the behavior of a particular size abutment pillar prone to burst or bump (local terminology). This information reflects the overriding influence of the local geologic characteristics on bursts, provides the field measurements needed to verify concurrent modelling studies, and suggests some basic mechanisms associated with coal pillar bursts. (PDF, 516 KB, 1990-08)

This report presents results of a U.S. Bureau of Mines study of longwall gob material. The objective of this work was to determine material stiffness properties of the gob for use in numerical models or rock mass response to longwall mining. (PDF, 5208 KB, 1993)

Injury data are presented that show a dramatic reduction in roof skin injuries when screening is used. Five case studies in which roof screen was used are presented along with the associated costs of materials, impact on bolting advance rates, and potential ergonomic risks. The effects of roof screening on skin control and safety are also included. Finally, this paper provides information about best practices and features of roof bolting machines that affect production and safety. (PDF, 141 KB, 2003)

This paper presents an overview of the most significant ground control hazards facing today's mineworkers, as well as best practices to reduce these risks. (PDF, 1971 KB, 2000)

The San Juan Mine and the National Institute for Occupational Safety and Health conducted a study to measure how development mining affected bolt loads. (PDF, 600 KB, 2004)

The Bureau of Mines developed a computerized method to calculate vertical stress exerted on surfaces at depth that includes the effect or topography. The limitation of the method is that stresses cannot be accurately determined near an outcrop. (PDF, 4167 KB, 1992)

Roof and floor contact pressure provided by the interaction of a shield with the surrounding strata are examined. Controlled forces were applied to an 800-ton two-leg shield using a mine roof simulator. (PDF, 4632 KB, 1992)

NIOSH, RAG Pennsylvania and Strata Control Technologies of Australia collaborated in an intensive study of ground behavior, reinforcement performance, and stress redistribution at the Emerald Mine in Southwestern Pennsylvania. The study site was a longwall tailgate subjected to a severe horizontal stress concentration. A computer simulation of the field site was conducted using FLAC-2D. Comparison between actual field measurements and the simulation showed that the model was able to capture the most significant aspects of the roof and support system behavior. The model also showed that supplementing the normal roof bolt support pattern with cable bolts would allow the entry to survive a further 20-25% increase in the applied horizontal stress. (PDF, 1254 KB, 2007)

Instrumented cable bolts were used in conjunction with existing ground control to monitor rock mass loads at various field sites. Axial and shear loads were determined by strain gauges as these loads were transferred to instrumented cable bolts. Cable bolt performance, quality of grout, and installation techniques were also assessed. By monitoring load on and discplacement of the rock mass, more effective ground support can be selected and installed, which will lead to safer working conditions for miners. (PDF, 3413 KB, 2001-07)

This paper presents the results of a case study conducted in a two-entry gateroad in a coal mine where excessive roof deformation and bolt loading resulted in failure of many roof supports. (PDF, 803 KB, 1998)

This report presents a Bureau of Mines study to identify the causes of self-heating events beneath the floor of a deep underground coal mine. The combined results led to the conclusion that pyrite oxidation was the prime cause of the heatings. (PDF, 4994 KB, 1992)

This study used microseismic emissions to help identify three local rock failure processes. It was also shown that analysis of microseismic emissions can aid in assessing the degree of instability associated with these local rock failure processes. (PDF, 312 KB, 2005)

Describes the procedures and thought processes used by coal mine geologists when determining various mineability and reserve extraction feasibility issues. The paper also address underground geologic hazard mapping and prediction techniques. (PDF, 152 KB, 2006)

Research on techniques that will reduce the hazards in the mining workplace associated with coal bumps. (PDF, 301 KB, 2000)
                                                

This paper presents several case studies in which a mechanics-based boundary-element program is used to back-calculate the surface subsidence associated with various panels at several northern Appalachian coal mines. (PDF, 448 KB, 1999)

Ground conditions at 10 Australian longwall mines and two room-and-pillar mines are compared with an extensive data base from U.S. mines. The comparisons include the Coal Mine Roof Rating, roof support installed, pillar design, and an in-depth discussion of ground control conditions. (PDF, 507 KB, 1998-08)

An investigation of an underground pillar at a mine in Lead, SD. Using the results, researchers hypothesize that pillar rocks have the ability to withstand stress an order of magnitude greater than they currently sustain. (PDF, 524 KB, 1999)

NIOSH has been conducting research to develop a new testing protocol for rating mine ventilation stoppings. This paper compares the transverse load capabilities of several block materials and wall dimensions commonly used in stopping constructions based upon simulated three-hinge, rigid-arch loading tests of half-wall constructions in the NIOSH Mine Roof Simulator. (PDF, 428 KB, 2008)

A computer analysis of bench stability was developed to account for multiple occurrences of potential slope-failure modes in discontinuous rock masses. Bench-scale plane shears and tetrahedral wedges are simulated and stochastically analyzed to estimate the probability of retaining specified catch-bench widths. (PDF, 625 KB, 2000)

A collaborative project was conducted to investigate ground behavior, reinforcement performance, and stress redistribution in a coal mine entry subjected to a severe horizontal stress concentration. This paper focuses on the computer simulation that was undertaken to provide more insight into the roof behavior and rock bolt interaction during mining. (PDF, 1100 KB, 2004)

Roof Monitoring Safety Systems (RMSSs) were installed in 13 underground limestone mines in six states. This paper analyzes the data obtained at three of the mines and also provides an overview of the system, data, analysis and applications relevant to the RMSS. (PDF, 1000 KB, 2003-08)

A design technique is presented which provides stone miners with a method for making stability assessments. The consequences of widening rooms, changing geology and horizontal stresses, and different rock bolts on roof beam failure are discussed. (PDF, 836 KB, 1998-08)

To study bump mechanisms, conditions in the vicinity of a deep longwall mining face in bump-prone strata were monitored using three discrete systems. Results from the three systems are correlated in an effort to increase understanding of mining-induced stress redistribution and bump potential. (PDF, 1090 KB, 2001)

A NIOSH study of the time-dependent response of rock stressed along weakness planes with the objective to improve mine safety by reducing the number of roof falls that cause injuries and fatalities to miners. (PDF, 119 KB, 2000)

The National Institute for Occupational Safety and Health is investigating various remote sensing technologies as possible tools to detect, monitor, and mitigate hazardous situations in surface mines that could lead to catastrophic slope failure. Promising technologies include a field-portable spectro-polarimetric imager and a stationary interferometric radar device. (PDF, 2162 KB, 2000)

As part of a research program to reduce injuries and fatalities in the U.S. mining workforce, NIOSH is investigating the potential use of noncontact vibration measurements to identify hazardous ground fall conditions. (PDF, 447 KB, 2004)

A study is described with the objective of evaluating the various methods and strategies by which panels, production pillars and barrier pillars are developed and extracted under deep cover, and to develop appropriate design guidelines. (PDF, 655 KB, 2002)

As part of an investigation aimed at improving the health and safety and competitiveness of the mining industry, the U.S. Bureau of Mines evaluated the application of common offset radar profiling, using a 250-MHz ground-penetrating radar (GPR) system, for the detection of fractures in igneous rock (PDF, 16185 KB, 1992)

The U.S. Mine Safety and Health Administration (MSHA) has identified ore pass hazards as s significant safety problem in underground metal mines in the United States. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are investigating these hazards and developing methods to improve safety during transport of ore and waste. (PDF, 677 KB, 1998)

The Spokane Research Laboratory (SRL) of the National Institute for Occupational Safety and Health (NIOSH) and Thiessen Team USA, Spokane, WA, have developed a pull claw that can be attached to any accessible friction bolt ring to test the performance (i.e., load-carrying capacity) of bolts without the use of a pull collar. This would allow true random testing of friction bolts, which need to be evaluated to determine if they are still providing an adequate level of support months or years after installation. Such support is critical to maintaining safe working conditions for underground miners. (PDF, 553 KB, 2004-03)

The purpose of this paper is to set goals for the future generations of longwall shields. (PDF, 877 KB, 2001)
                                                              

One focus of ground control research at NIOSH is to incorporate data on weak rock masses into existing design relationships, with an emphasis on updating the span design curve for manned entries and the overbreak curve for longhole entries. Both curves were originally developed at the University of British Columbia, Vancouver, BC. The original database has been augmented by information from mines throughout the United States, Canada, Australia, and Europe. The common factor in all of these mines is the presence of a weak back and/or walls. In most cases, the ore zone is the weakest rock unit and must be stabilized so that the mineral-bearing rock can be extracted safety. The current NIOSH research attempts to provide rock mechanics tools to assist a mine operator in making economic decisions that will also ensure a safe working environment. This paper documents the Nevada database with a special emphasis on Nevada underground gold mines. (PDF, 396 KB, 2005)

This paper discusses a design methodology for standing secondary tailgate supports. The methodology uses the performance characteristics generated in the NIOSH Mine Roof Simulator (MRS) to match the stiffness and load characteristics of various supports to the measured ground reaction behavior. (PDF, 666 KB, 1999)

Methods are described to limit "cascading pillar failure", which occurs when one pillar in a mine layout fails, transferring its load to neighboring pillars, which causes them to fail, and so forth. Design approaches are illustrated with practical examples for coal mining at shallow depth. (PDF, 624 KB, 1997)

A study is described where information was collected at 37 coal mine on roof falls, and other geotechnical, mining, geologic and roof bolting factors. A statistical analysis was conducted on the data with the roof fall rate being the outcome variable. (PDF, 588 KB, 2001-06)

A calibrated three-dimensional finite element model, developed in conjunction with an underground test area, provided the critical components and design principals for a comprehensive parametric study. (PDF, 329 KB, 2004-02)

The underhand method under consolidated fill ensures a high recovery under an engineered back that is comprised of cemented rock fill and/or cemented paste fill. This method of mining is generally necessary either due to a weak rock mass comprising the immediate back and/or high induced back stresses. A major concern in the design of sill mats is the loading and strengths associated with the overlying sill mat. This paper reviews past practice coupled with present observations and measurements from over ten mines throughout North America related to mining under consolidated fills. (PDF, 386 KB, 2005)

Slope stability accidents are one of the leading causes of fatalities at U.S. surface mining operations. The National Institute for Occupational Safety and Health is conducting research to reduce the fatalities associated with slope failures. This paper discusses some of this research and presents potential new technologies for slope monitoring and design. (PDF, 329 KB, 2002-08)

As part of safety and stability studies at three underground mines in the United States, researchers installed earth pressure cells and embedment strain gauges in cemented rockfill to measure stress and strain changes as mining progressed and the rockfill was loaded. Data from these instruments were used to calculate the in situ modulus of the rockfill for two of the mines. A three-dimensional numerical model of a cemented rockfill cap was validated with data from extensometers anchored in the mine roof and sill; this model was then used to estimate deformation modulus at the third mine because the earth pressure cells and embedment strain gauges recorded negligible changes. (PDF, 757 KB, 2003-09)

Researchers are investigating the physical properties of cable bolts by replacing the conventional king wire with a modified king wire on which strain gauges have been installed. (PDF, 621 KB, 2000-04)

Researchers from private industry and NIOSH have studied mechanisms of violent failure and have identified individual factors that contribute to coal bumps. In an attempt to develop tools for assessing coal bump potential, the authors initiated a comprehensive study using information from 25 case studies undertaken in U.S. mines. (PDF, 331 KB, 1997)

An automated PC-network-based seismic data acquisition and processing system has been developed by NIOSH for use in mine safety studies. Several systems have been constructed and deployed in the field for testing and application. These systems are now being applied in studies designed to reduce hazards associated with roof falls, rock bursts, coal bumps, and mine collapse. (PDF, 264 KB, 2001-12)

This paper presents the results of a study into the ground response around tailgate entries using numerical models. The ground response is shown to be significantly affected by the strength of the immediate roof as well as the main roof. The importance of yield capacity of standing support is demonstrated. Gob height and compaction are found to affect the amount of convergence in the tailgate. The potential exists to develop site-specific tailgate design curves by combining model results with field observations. (PDF, 587 KB, 2006-06)

A new protocol based on rigid arch loading of the structure is proposed to determine the true transverse load capacity of block stoppings. The rigid arch tests have shown that the load capability is dependent on the physical properties of the block and geometric properties of the wall, not the sealant. (PDF, 338 KB, 2006-06)

A system was developed to monitor rock and coal stresses during mining of an entire longwall panel. The system was designed to generate data in near real time to evaluate rock behavior in roof strata and the onset of hazardous conditions as overburden stress was redistributed over working entries during gob formation. Computer simulations and in-mine evaluations were used to optimize instrument placement. A prototype packer assembly was designed and tested for installing sensitive instruments in a mine roof. This paper provides background information on the stress monitoring concept and focuses on the development of instrument placement techniques and the prototype packer assembly. (PDF, 654 KB, 2001-07)

During the past few years, NIOSH has been evaluating developments in sealant support systems from a ground control perspective. This paper briefly reviews the current state-of-the-art technology in shotcrete and membrane developments, evaluates the preliminary findings of a long-term underground study of various types of sealant materials, and examines installation practices that are critical for an effective sealant material. (PDF, 462 KB, 2002-08)

Various methods of monitoring slip movements on bedding planes, as well as examination of rock burst damage in stopes, suggests that rock bursts in the Lucky Friday Miner are closely associated with these movements. (PDF, 929 KB, 1999-06)

A large Pittsburgh seam longwall mine had begun to develop in a different direction from its original portal area to access additional reserves. A large area of the mine would be abandoned and sealed, but continued use of the original mine portal area required that the water accumulating in the abandoned mine would eventually need to be pumped to the surface. Several pumping and sump options were investigated to handle the quantity and quality of the anticipated discharge water. (PDF, 764 KB, 2001)

The process of drilling and bolting the roof is currently one of the most dangerous jobs in underground mining, resulting in about 1,000 accidents with injuries each year in the United States. Researchers from the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are studying the use of a drill monitoring system to estimate the strength of successive layers of rock and assess the integrity of a mine roof so that roof drill operators can be warned when a weak layer is being drilled. (PDF, 2025 KB, 2002-07)

Standing crib supports have been applied in underground mining programs to resist large roof movements and sustain high-loads. The parameter that has not been examined and is not well understood is the effect that a crib or other types of standing support has on the primary and secondary bolting systems. Utilizing a combination of field measurements and 3-dimensional finite element modeling techniques, the relationship between system stiffness and the subsequent performance of the installed bolting system is evaluated. (PDF, 248 KB, 2003-08)

Underground limestone mines typically use the room-and-pillar method of mining in the generally flat-lying limestone formations. In some cases the dip may exceed 5° which can result in unique roof instability problems. Stability may be further exacerbated by the presence of horizontal tectonic stresses. Field studies and numerical model analyses are combined to assess the effect of the dip in various stress conditions. (PDF, 1007 KB, 2005)

NIOSH researchers installed 39 instrumented, fully grouted bolts at six test sites in a trona mine retreat panel to study mine roof stability for the improvement of workplace safety. (PDF, 318 KB, 2001)

Researchers are investigating the causes and mechanisms of roof failure in underground mines. It is expected that a better understanding of these causes and mechanisms will lead to better layout and support designs that will help prevent accidents and fatalities associated with fall of ground. (PDF, 1531 KB, 2004)

This U.S. Bureau of Mines paper discusses the importance of an interface slip mechanism between the coalbed and the surrounding strata in controlling the extent and pattern of stresses and deformations in a coal pillar. (PDF, 531 KB, 1990)

Observations of pillar conditions in limestone mines showed that the presence of weak bands in the limestone can result in pillar damage at stresses that are lower than one would otherwise expect. The objective of this NIOSH study was to investigate the mechanism of failure caused by the presence of weak bands by using a series of numerical models based on realistic physical properties. (PDF, 1398 KB, 2007)

The U.S. Department of Energy Pittsburgh Research Center, has developed and field tested a spatial, spectral sensor for measuring the thickness of mineral deposits. (PDF, 30 KB, 1996)

This paper discusses a) the results of a ground-based hyperspectral imaging tool used to map the geology of an open-pit mine highwall; and b) interferometric synthetic aperture radar and how it can be used in a variety of geotechnical situations. It is hopeful that these new developments will lead to better geotechnical monitoring and design in slope stability and other important areas of rock mechanics. (PDF, 468 KB, 2001)

A major focus of ground control research presently being conducted by the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) is to incorporate weak rock masses (such as are associated with operations in the Carlin Trend in Nevada) into existing design relationships. The original database that led to most of the empirical design relationships presently employed in hard-rock mining was derived from fair-to-good-quality rock. In this study, the relationship between weak rock quality and opening design (non-entry/entry methods) is being investigated. The common factor in all mines is a weak back or wall. This work attempts to provide tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment. (PDF, 334 KB, 2005)

A major focus of ground control research is to incorporate weak rock masses (such as are associated with operations in the Carlin Trend in Nevada) into existing design relationships. The original database that led to most of the empirical design relationships presently employed in hard-rock mining was derived from fair-to-good-quality rock. In this study, the relationship between weak rock quality and opening design (nonentry/entry methods) is being investigated. The common factor in all mines is a weak back or wall. This work attempts to provide tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment. (PDF, 401 KB, 2003)

This paper presents a focus of ground control research presently being conducted by the Rock Mechanics Group in the DBC Mining Department in incorporating weak rock masses (RMR₇₆ <50) into existing empirical design relationships. This work attempts to provide rock mechanic tools that will enable a mine operator to make economic decisions that will also ensure a safe working environment. (PDF, 115 KB, 2008)

The goal of this project was to design and evaluate devices that can be installed with traditional primary or secondary roof supports, and that are easy to handle/install under temporary or previously supported roof. (PDF, 5119 KB, 2001)

Researchers at the U. S. Bureau of Mines conducted investigations to evaluate the potential for ground watercontamination by mine waste used as backfill. Samples of cemented waste backfill and water discharging fromdrillholes and seeps were collected to use in chemical analyses and laboratory tests to determine the physical andchemical factors that control release of heavy metals to ground water. (PDF, 351 KB, 1996)

Researchers at the U.S. Bureau of Mines investigated the use of close-range photogrammetry and subsequent stereo digitizing to obtain data from rock fracture roughness profiles. (PDF, 3830 KB, 1993)

Several remote-sensing technologies are being evaluated as tools to monitor slopes for hazards and to assess slope stability. (PDF, 3017 KB, 2002)
                          

Instrumented cable bolts developed at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health were used in conjunction with existing ground control systems to monitor rock mass loads at Tg Soda Ash's trona mine in Granger, WY. (PDF, 664 KB, 2001)

Whereas many researchers and mine engineers have conducted tests on cable bolts using various grouts, water:cement ratios, and physical modifications of the cable to determine the load-carrying characteristics of a bolt, few studies have been conducted on cable bolts fitted with internal instruments. Researchers at the Spokane Research Laboratory (SRL) of the National Institute for Occupational Safety and Health in Spokane, WA, are investigating the physical properties of cable bolts by replacing the conventional king wire with a modified king wire on which strain gauges have been installed. (PDF, 615 KB, 2004-04)

Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. (PDF, 253 KB, 2007)

Studies conducted have identified a number of "risk factors" that can be used to evaluate pillar extraction plans: cut sequence; final stump; timber or mobile roof supports; roof bolting; intersection span; depth of cover; roof quality; and age or workings. This paper discusses each of the risk factors in turn, presents the relevant accident statistics, and shows how the risk factors can be combined to estimate the overall hazard. (PDF, 636 KB, 2002-08)

Polyurethane injection is a proven method of rock stabilization in even the weakest, most broken ground. Optimization of the injection design by pre-injection video diagnostics can greatly contribute to the successful and efficient roof stabilization. (PDF, 373 KB, 2004)

To help evaluate the usefulness of the natural gamma radiation (NGR) technique for the coal interface detection (CID) project, the U.S. Bureau of Mines (USBM) collected data from various mining companies conducting underground and surface operations in 15 major and 110 minor coal seams in the United States (1).2 This work was done in support of the USBM goal to improve the method of recovering coal from the nation's mines in a safe and economical manner. (PDF, 2527 KB, 1995)

A cooperative study was conducted to evaluate the effectiveness of (partially) pre-driven longwall recovery rooms supported with pumpable roof supports. This paper evaluates the load transfer mechanics associated with the advancement of the longwall face into the pre-driven recovery room and the widening of the room to recover the longwall shields. (PDF, 608 KB, 2007)

Numerical modeling is used to evaluate the degree the pillar strength is increased with a rectangular pillar over a square pillar. (PDF, 164 KB, 2007)

The conclusion drawn from this study was that standing supports do not have sufficient capacity to control main roof or floor loading or prevent the resulting convergence of the tailgate entry. (PDF, 255 KB, 2005)

This paper investigates some of the issues affecting pillar strength at low width-to-height ratios in hard, brittle rock. The investigation includes an evaluation of empirical pillar strength data presented in the literature and observations of pillar performance in underground limestone mines in the Eastern United States, supplemented by numerical modeling in which failure processes and sensitivity of slender pillars to variations in rock mass properties are evaluated. The results showed that the strength of slender pillars is more variable than that of wider pillars. (PDF, 1206 KB, 2006-01)

Investigates some of the issues affecting pillar strength at low width-to-height ratios in hard, brittle rock. The investigation includes an evaluation of empirical pillar strength data presented in the literature and observations of pillar performance in underground limestone mines in the Eastern United States, supplemented by numerical modeling in which failure processes and sensitivity of slender pillars to variations in rock mass properties are evaluated. (PDF, 677 KB, 2006)

A new protocol based on arching has been developed to determine the true transverse load capacity of stoppings. (PDF, 7182 KB, 2005)
                                        

This paper discusses progress in the science of coal pillar design over the past 25 years and some of the current research needs. (PDF, 664 KB, 2006)
                      

This report examines shield design and operation practices and their consequences for the utilization of high-capacity shield support systems. An optimization goal is to minimize support loading by selecting an active shield setting force that is compatible with strata behavior and shield loading characteristics. (PDF, 1569 KB, 1992)

A close look at the Loyalhanna Limestone of southwestern Pennsylvania reveals a complex structural environment.  Geologic and engineering analyses were performed using gas well and core logs, outcrop examinations, underground observations, and mine maps. Many of the structural conditions cause ground control problems at local quarries. (PDF, 2678 KB, 2002)

NIOSH is conducting research aimed at helping mine planners prevent hazardous conditions due to multiple-seam interactions. More than 300 case histories have been collected from underground mines mainly in central Appalachia. This paper focuses on several of the more challenging situations that have been encountered, including: room-and-pillar development 20 ft beneath full-extraction workings at a depth of 1,000 ft of cover; pillar recovery 45 ft above full-extraction workings at 900 ft of cover; near-simultaneous room-and-pillar mining with pillar recovery with 40 ft of interburden and 1,500-2,000 ft of cover; and longwall mining directly beneath main entries in overlying seams. (PDF, 629 KB, 2006)

NIOSH is using the experience of U.S. coal mines to determine the factors which influence intersection instability and provide guidelines for the safe excavation and support of intersections. By using the roof fall rate as the outcome variable, correlations between roof geology, intersection span, and roof support have been established. (PDF, 523 KB, 1998-08)

The location and time of 2,007 microseismic emissions from a limestone mine in southwestern Pennsylvania were compared with the development of mine faces and the characteristics of the mine layout. Based on analyses of these results, the occurrence of roof failure zones appears to be associated with certain characteristics of the mine plan. (PDF, 617 KB, 2001)

This research seeks to provide design guidelines that enable mine planning engineers to correctly assess the safety risk of an adverse multiple seam mining interaction based on mine geometry factors, mine layout factors and site specific geologic conditions. (PDF, 425 KB, 2005)

This paper looks at the feasibility of using noncontact laser-based vibration measurements to detect roof fall hazards with the ultimate vision of improving, expanding and automating procedures for mine roof inspection. (PDF, 369 KB, 2002)

This study presents a historic overview of the role of mobile roof support (MRS) technologies in improving stability and worker safety and presents the results of recent field evaluations of the MRS load rate monitoring device and other remote deformation-monitoring techniques. (PDF, 847 KB, 2001-08)

This paper describes a modeling approach that can be used as a tool to evaluate potential roof failure and optimize the stability of room and pillar layouts. (PDF, 974 KB, 2008)

This paper reports on an extensive series of short-encapsulation pull tests that were conducted in the NIOSH Mine Safety Research Laboratory and operating mines in WV and PA. (PDF, 334 KB, 2003)

To measure the loading behavior of friction bolts, NIOSH researchers installed strain gauges on the interior of friction bolts and developed a battery-powered miniature data acquisition system (MIDAS) that fits inside the hollow portion of the friction bolt. (PDF, 594 KB, 2003-08)