Effects of moisture on strata control in coal mines

Moisture has been known to influence strata failures in coal mines for a long time. However, it is only in the last decade that researchers have attempted to quantify this effect. In the laboratory, attempts have been made to study the effects of moisture on the strength of coal-bearing rocks, moisture gain in shales as a function of time and pressures generated due to swelling, slaking and swelling indices and their possible correlation to strata control problems, and effect of humidity variations on anchor creep and bearing plate performance in conjunction with conventional bolts. In the field, researchers have attempted to correlate humidity variations with the incidence and frequency of roof falls and roof convergence, and effects of air tempering on reducing humidity variations in the mine.

A concise review of what is known about effects of moisture on strata control with emphasis on the Illinois basin coal mines is presented in this paper. Some approaches to mitigate the effects of moisture—leaving coal in the roof, guniting and shotcreting, application of sealants—are then briefly discussed.