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Direct measurement of longwall strata behavior: a case study.

Authors
Listak-JM; Hill-JL III; Zelanko-JC
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9040, 1986 Jan; :1-19
Link
NIOSHTIC No.
10005313
Abstract
The Bureau of Mines has conducted a rock mechanics study to monitor deformation of near-seam strata above a longwall panel in the Pittsburgh coalbed. The primary goal was to determine the height of caving immediately behind advancing longwall face supports. This study, although site specific, provides information on the caving mechanism associated with longwall extractions so that strata behavior and its interaction with longwall face supports can be better understood. Two holes were drilled, approximately 550 ft apart along the centerline of a longwall panel, from the surface to the coalbed approximately 650 ft below. Various downhole geotechnical instruments were used to monitor strata deformation. In addition, surface elevation surveys were conducted to differentiate between surface and subsurface activity. This report discusses the caving characteristics of the strata as the longwall panel approached and passed beneath the boreholes. Physical property data are also presented to demonstrate the relationship between caving behavior and local geology. Data show that immediate caving of strata above the longwall face occurred at a height less than 23.5 Ft and that strata behavior above longwall extractions is highly dependent upon lithology, with major disturbances occurring at weak lithologic zones.
Keywords
Strata; Longwall-mining; Mining-research; Lithology; Rock-mechanics; Mineral-industries
Publication Date
19860101
Document Type
IH; Report of Investigations
Fiscal Year
1986
NTIS Accession No.
PB87-167466
NTIS Price
A03
Identifying No.
RI-9040
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9040
State
PA
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