January 2001
Volume 53    Issue 1

New development in the testing of rocks

Mining Engineering , 2001, Vol. 53, No. 1, pp. 26-32
Unrug, K.F.; Thompson, E.; Altizer, D.

High productivity in mining operations results in the fast movement of faces. Consequently, the chances of encountering changes in the geologic conditions increases. Longwall panels in coal mines are now very large. Their lengths can reach 6,100 m (20,000 ft) and they can be 300-m (1,000-ft) wide. The probability that rock conditions will change over such large panel areas is quite high. It is known that the extrapolation of rock characterization from the location of the exploration hole to the surrounding area often leads to unrealistic assumptions. Sandstone channels and slumps that cause sudden changes in mining conditions, including such dramatic features as washouts of a seam itself, often complicate the geology of carboniferous strata. Similarly, in tunneling and, especially, in mixed face configurations, changes in rock parameters can be substantial beyond the range of expected values.

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