Data & statistics

100 Years of Improvement in Aggregate Worker Safety (PDF, 6810 KB, 2003-03)
The aggregates industry faces a number of challenges in the near future, including the loss of experienced mine workers due to retirement, an influx of new, inexperienced workers and more challenging mining conditions. More effective training is needed to reduce injuries of both experienced and inexperienced workers from ever increasing diverse background. The awareness and involvement of the whole workforce needs to be fostered by management, labor and government jointly identifying risk factors, selecting mining practices, implementing mining plans and engineering and administrative controls.

History

Historic Coal Mine Bump Data (HTM, 2000-11)
These reports and documentation on past coal mine bump events were collected by NIOSH and the former U. S. Bureau of Mines.

Software

CMRR - Coal Mine Roof Rating
The Coal Mine Roof Rating is a roof classification system that was first introduced to the mining community in 1994. The CMRR is a rock mass classification system which calculates the inherent strength of coal mine roof. It can be used in the design of gateroads, roof bolt selection, extended-cut decisions, and numerical modeling.

Guides

Best Practices to Mitigate Injuries and Fatalities from Rock Falls (PDF, 1971 KB, 2000)
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.

Measurement & analysis

Application of the Coal Mine Roof Rating (CMRR) to Extended Cuts (PDF, 313 KB, 1999-04)
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.

An Approach to Identifying Geological Properties from Roof Bolter Drilling Parameters (PDF, 724 KB, 2000)
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.

Coal Mine Geology in the U.S. Coal Fields: a State-of-the-art (PDF, 152 KB, 2006)
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.

Comparison of Ground Conditions and Ground Control Practices in the United States and Australia (PDF, 507 KB, 1998-08)
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.

Mapping Hazards with Microseismic Technology to Anticipate Roof Falls - A Case Study (PDF, 855 KB, 2004-08)
More that 700 microseismic emissions were collected from two underground limestone mine roof fall areas in southwestern Pennsylvania. Microseismic events were located and magnitudes determined using the moment magnitude technique. The amount of new fracture surface length was calculated based on the stored strain energy within the rock prior to fracture. A significant amount of microseismic activity was observed as much as two days before the first signs of failure in the roof fall areas. Additionally, results from this analysis reveal much about the behavior of strata prone to failure and allows for the construction of hazard maps based on microseismic emissions.

Modeling the Effects of Longwall Mining on the Ground Water System (PDF, 308 KB, 1995)
A hydrologic-subsidence investigation was performed to evaluate the effects of longwall mining on the local ground water regime through field monitoring and numerical modeling. A combined finite element model of the deformation of overlying strata, and it's influence on ground water flow was used to define the change in local and regional water budgets.

Proceedings of the International Workshop on Rock Mass Classification in Underground Mining (PDF, 10425 KB, 2007-05)
Rock mass classification is widely used throughout the underground mining industry-in both coal and hard-rock mines. It is used in all stages of the mining process, from site characterization to production operations. The goal of the International Workshop on Rock Mass Classification in Underground Mining was to provide a forum for leading practitioners of rock mass classification to come together and share their methods and experiences with the technique. The proceedings of the workshop contain 16 invited papers from 9 countries, reflecting the international depth and breadth of current practice. Applications in both hard-rock and coal mining are well represented.

Roof Stability Issues in Underground Limestone Mines in the United States (PDF, 700 KB, 2007)
This paper presents the results of a study of roof conditions in 34 limestone mines in the Eastern and Midwestern U.S.

Root Causes of Groundfall Related Incidents in U.S. Mining Industry (PDF, 620 KB, 2003-08)
This paper utilized the rock fall related incident narratives from the MSHA database for a taxonomic analysis, which identifies the root causes of an event and can provide future direction for corrective measures to reduce the probability of occurrence of the event.

Shear Strength Evaluation of Clay-Rock Mixtures (PDF, 2209 KB, 2000)
This study reviewed 31 technical papers which contain analysis of shear strengths for clay and sands with varying mixtures of rock particles. These technical papers, published over the last 40 years, are comprised of field case studies, laboratory investigations, and theoretical analysis. Evaluation of this body of knowledge has shown that the shear strength gradually increases with increasing percentages of floating particles in unsaturated clays.

Spatial Trends in Rock Strength - Can They Be Determined From Coreholes? (PDF, 290 KB, 2004)
Rock mechanics testing is central to a geotechnical exploration program and typically, average uniaxial compressive strength (UCS) is the measure used to quantify a particular roof unit at a given corehole. Issues are that the average UCS may differ between coreholes but not be statistically significant; and whether or not widely spaced coreholes can identify valid spatial trends in rock strength. The paper describes NIOSH's extensive investigation of these issues.

Technology News 478 - Apparatus for Measuring the Gas Content of Coal or Rock Core Samples (PDF, 56 KB, 1999-08)
An apparatus is described that advances the state of the art in gas content testing of coal or rock core samples. The design goals were to improve sensitivity/accuracy, durability, and ease of operation.

Using the Coal Mine Roof Rating (CMRR) to Assess Roof Stability in U.S. Coal Mines (PDF, 1209 KB, 2001)
The Coal Mine Roof Rating (CMRR) has been developed to quantify the defects in the rock mass and compile a strength value which can be used for engineering design. The CMRR has been applied to a number of ground stability problems, including chain pillar design, roof bolt selection, hazard assessment, intersection design, and numerical modeling. The CMRR procedure and some of these applications are described in this paper.

Using the Point Load Test to Determine the Uniaxial Compressive Strength of Coal Measure Rock (PDF, 482 KB, 2000)
Point load testing is used to determine rock strength indexes in geotechnical practice. A study was conducted where more than 10,000 individual test results, from 908 distinct rock units, were used. This allowed for intact rock strength data to be made available through point load testing for numerical geotechnical analysis and empirical rock mass classification systems such as the Coal Mine Roof Rating.

Engineering controls

Design of Primary Roof Support Systems in U.S. Coal Mines Based on the Analysis of Roof Fall Rates (PDF, 588 KB, 2001-06)
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.

Discharge Water Handling and Treatment: Problems and Solutions at a Large Pittsburgh Seam Coal Mine (PDF, 764 KB, 2001)
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.

Geologic Hazards and Roof Stability in Coal Mines (PDF, 3940 KB, 2003-10)
This report describes the geologic origin, association, and potential danger from the most common hazards. Discussions of weak rock include drawrock, rider coals, head coal, stackrock, and stream valley effects.

Geology Roof Control and Mine Design (PDF, 708 KB, 2001-12)
Geology is an integral part of roof control, mine design, and production operations. Yet, the importance of geology, coal/rock as an engineering construction material and its properties and behavior within the planned mine areas, in overall mine production operations has not been fully appreciated. Understanding the nature of roof geology could explain why roof control plans sometimes fail.

Preventing Falls of Ground in Coal Mines With Exceptionally Low-Strength Roof: Two Case Studies (PDF, 184 KB, 2004)
Mines with exceptionally low-strength roof are much more likely to struggle with roof falls that other mines. This paper focuses on two mines, one operating in the Upper Freeport seam and the other in the Herrin No. 6 seam. Detailed statistical analysis was conducted to determine which support combinations have proven to be most effective.

Laboratories

MTS Rock Mechanics Testing Laboratory
Small scale testing of materials.

Seismic Laboratory
Supports field measurement and analyses of seismic event activity produced by dynamic rock mass failures.

Soil/Rock Properties Laboratory
Provides the capability to wash, screen, dry, and mix unconsolidated materials such as soils prior to testing by various test frames.

Meetings, workshops & seminars

Technology News 526 - Proceedings of the International Workshop on Rock Mass Classification in Underground Mining (PDF, 88 KB, 2007-07)
Rock mass classification is widely used throughout the underground mining industry - in both coal and hard-rock mines. The technique has been successful because it 1. Uses simple measurements to rate rock mass strength. 2. Helps mine planners to make the best use of geologic information in mine design. 3. Makes it possible to compare ground control experiences between mines, even when the geologic conditions are very different. The International Workshop on Rock Mass Classification in Underground Mining provided a forum for leading practitioners of rock mass classification from around the world to come together and share their methods and experiences with the technique.