Mining Project: Design Methodology for Rib Control in Coal Mines

Principal Investigator	Khaled Mohamed - Request information
Start Date	10/1/2016
Objective	To reduce the number of rib fall accidents in Eastern U.S. underground coal mines by developing an engineering-based design methodology that defines the appropriate level of rib support.
Topic Area	Ground Control Overview

Research Summary

Currently, rib support systems in U.S. coal mines are primarily designed using a trial-and-error approach. 30 CFR and related legislation have not established any minimum design requirements for rib control systems. Because of this lack of a minimum rib control requirement in underground coal mines, the coal mining industry continues to suffer from rib-related injuries and fatalities. During the ten-year period of 2006 through 2015, 11 fatalities and 668 non-fatal days lost (NFDL) injuries caused by rib falls were documented by the Mine Safety and Health Administration (MSHA). According to MSHA statistics, between 2010 and 2015, 86% of the rib fatalities in U.S. underground coal mines occurred in the Eastern coal basins (Appalachian and Illinois coal basins). About 88% of the NFDL injuries occurred in the Eastern U.S. coal basins. Based on these injury statistics, more emphasis should be devoted to reduce rib fall incidents in coal mines operating in the Eastern coal basins. This can be done by developing an engineering-based design methodology that defines the appropriate level of rib support.

To address this issue, this project has four research aims, as follows: (1) develop a logical procedure for a Coal Pillar Rib Rating (CPRR); (2) improve the understanding of coal rib deformation and rib-support interaction; (3) identify critical parameters affecting rib stability; (4) develop and test the design methodology for rib control.

In the first year, this project research will create a CPRR rating system that will be used to define the anticipated failure mode of the rib. The research will develop data collection protocols for visited mine sites and a systematic procedure for computing the CPRR. Compressive strength testing will be conducted for rib units (coal and rock). By the end of the project, this rating system will then be used to define the required support to be installed to prevent accidents that caused rib falls. These support designs will be based on engineering stress models that have been evaluated and verified at several underground mines through monitoring.

In the second and third years of this project, NIOSH researchers will monitor coal rib and support response at study sites, conduct compressive strength testing for rib units, calibrate the rib model using the field monitoring studies, verify the calibrated rib model using published rib monitoring case studies, and present papers about the project findings at international conferences. In the fourth and final year of the project, researchers will conduct parametric studies of factors affecting rib stability, establish statistical relationships between the critical parameters and rib stability factors, develop a tool to design and analyze rib stability, and publish the project findings in a peer-reviewed journal.

The ultimate goal of the proposed project research is to reverse the current trend of rib fall incidents in Eastern coal basins. The achieved minimum rib support standards could be adopted by enforcement agencies that approve rib control plans.

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