One Hundred Years of Federal Mining Safety and Health Research

Figure 36. Air currents when using the shearer-clearer system.
The Bureau’s in-house and contract respirable dust research program was assisted by the GMTC
for Respirable Dust. This group of universities led by the Penn State University and West
Virginia University conducted government-funded research on the measurement and control of
respirable dust and other hazardous aerosols in mines. The GMTC for Respirable Dust research
also included biomedical studies that helped increase understanding of the causes and
mechanisms of coal workers’ pneumoconiosis. This critical work was closely coordinated with
that of the Bureau and NIOSH. The GMTC for Respirable Dust not only produced a great deal
of important research results, but also helped train dozens of graduate students for work in the
mining industry and elsewhere.
5.6.2 Ground Control
One of the largest subprograms of the Bureau in this period was ground control research to
prevent injuries from falls of roof and rib in underground mines, which are generally a leading
cause of mining fatalities. Research on developing instrumentation and methods to detect
hazardous ground conditions included work on borehole extensometers, continuous roof
displacement recorders, and mechanical and ultrasonic convergence meters. These devices
measured roof to floor convergence and roof strata separation that could indicate imminent roof
failure. Geophysical techniques, including microseismic monitoring, were studied that could be
used to help warn of impending roof failure. Microseismic activity or acoustic emissions are
low-level noises that emanate from stressed rock in underground mines. This approach was
discovered and studied by two Bureau researchers, Leonard Obert and Wilbur Duvall, in the
1930s.
After the 1969 Coal Act, the Bureau continued research to improve the roof bolting process that
had become the principal roof support method in American underground mines. Bureau research
helped establish industry practices for anchorage and load capacity for various roof bolting
systems. Investigations were made into new roof control concepts including a pumpable roof
bolt, a yielding roof bolt, a flexible helical rock bolt, and various bolt grouts. These studies
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