Effects of Temperature and Humidity Variations on the Stability of Coal Mine Roof Rocks. Final Report.
NTIS: PB/262-516 Available for Reference At Bureau Libraries :385 pages
A high degree of correlation between strain developed in samples of roof rock and humidity changes was obtained in the laboratory. The strain developed across bedding planes was greater than strain developed parallel to bedding. In tests conducted underground, strain values were much lower and the data more scattered for similar humidity variations. Roof rock specimens reacted to a 10 pct change in humidity throughout a 7- to 10-day period before stabilizing, which seems to rule out daily humidity cycles as a factor in roof deterioration and indicates seasonal variations as a major cause. Very low annual temperature variations were recorded in active sections of the mine. At a 6 deg f annual variation developed strain would be only 10.5 Mocroinches per inch, far below the strain magnitude for humidity variations and probably too low to be a factor in problems of roof deterioration. Laboratory strain tests on drill core samples were shown to be indicators of moisture sensitivity of roof rock, but neither chemical nor physical properties of the samples correlated with the strain data.
CP; Final Contract Report;
NTIS Accession No.
NTIS: PB/262-516 Available for Reference At Bureau Libraries
University of Alabama