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Clay veins: their occurrence, characteristics, and support.

Authors
Chase-FE; Ulery-JP
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9060, 1987 Jan; :1-19
NIOSHTIC No.
10005605
Abstract
Clay veins found in coal mines have caused numerous injuries and fatalities. These structures plague all phases of mining, including entry development, pillar recovery, and panel extraction. Clay veins also increase production costs and may disrupt or halt mining. These detrimental aspects have prompted the Bureau of Mines to investigate the physical characteristics of and roof instability problems associated with clay veins. This was accomplished by observing and mapping clay veins in surface and underground mines. The occurrence and origins of clay veins were also investigated to determine predictive capabilities. The investigators found that clay veins normally occur in more stable, less rapidly subsiding coal basins. Clay veins result when tensile stresses develop fissures that are later infilled. These fissures can be propagated by compactional processes and/or tectonic stresses during and subsequent to coalification. The Bureau also found that associated faults, fractures, and slickenside planes commonly parallel clay veins and disrupt the lateral continuity of the immediate and, sometimes, main roof. When clay veins parallel or subparallel the direction of face advance, the roof is segmented into cantilever beams, causing unstable conditions. Consequently, the strata on either side of the clay veins should be bolted and strapped together to form a beam.
Keywords
Surface-mining; Surface-properties; Underground-mining; Mining-industry; Coal-mining; Structural-analysis; Room-and-pillar-mining; Injury-prevention; Injuries; Traumatic-injuries
Publication Date
19870101
Document Type
IH; Report of Investigations
Fiscal Year
1987
NTIS Accession No.
PB87-204517
NTIS Price
A03
Identifying No.
RI-9060
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9060
State
PA
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