Effects of ancient stream channel deposits on mine roof stability

Technical Report · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6539621

Ingram, D K; Chase, F E

The Bureau of Mines conducted underground mapping and rock strength tests to describe and analyze mine roof conditions surrounding ancient stream channel deposits (paleochannels) in the Pittsburgh Coalbed in southwestern Pennsylvania. Paleochannels in the study mine consist of sandstone and/or siltstone and affect the Pittsburgh Coalbed through erosion and/or differential compaction. Differentially compacted sediments within and adjacent to channel deposits caused slip planes, faults, clay-dike faults, clastic dikes (clay veins), coalbed rolls, and slumped structures. Paleochannels can be predicted by recognizing these features and associated sediments, which allows for modification of long-and-short-term mine planning and development. Mine entries located beneath the paleochannel deposits exhibit less stable roof conditions than entries with normal (nonchannel) roof. Paleochannel deposits comprise only one-fourth of the mapped study area: however, they contain one-half of the hazardous roof. This study has determined that rock strength evaluations must be accompanied by underground observations. Suggested remedial support techniques include angled and/or longer tensioned bolts, steel mats or crossbars, steel sets or cribbing, and roof trusses.

• Research Organization: Bureau of Mines, Pittsburgh, PA (USA)
• OSTI ID: 6539621
• Report Number(s): RI-9092
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
012031* -- Coal
Lignite
& Peat-- Underground Mining-- Strata Mechanics & Control-- (1987-)
COAL MINING
DEFORMATION
GROUND SUBSIDENCE
HAZARDS
HYDROLOGY
MINING
ROCKS
STRATA CONTROL
UNDERGROUND MINING