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Behavior of simulated longwall gob material.

Authors
Pappas-DM; Mark-C
Source
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9458, 1993 Jan; :1-39
NIOSHTIC No.
20022667
Abstract
This report presents results of a U.S. Bureau of Mines study of longwall gob material. The objective of this work was to determine material stiffness properties of the gob for use in numerical models of rock mass response to longwall mining. Photographs of actual mine gob were digitized to obtain approximate particle size gradations of gob material. The gradation curve was shifted down to a laboratory scale, and 20 uniaxial compression tests were conducted. Varying the maximum particle size was not found to affect the stress-strain behavior, but changing the gradation appeared to influence the stress-strain behavior. The stress-strain realtionship of the simulated gob material was nonlinear, the stress-secant-modulus relationship was approximately linear, and the stress-tangent-modulus relationship was approximately a second-order polynomial function. Equations were generated from these curves, providing numerical modelers with a means to estimate gob moduli based on the stress level. In addition, the experimental data were statistically evaluated using multiple regression analyses, producing a series of equations to predict the scant and tangent moduli from the given stress level, bulking factor, rock strength, and thickness-to-width shape ratio of the particles.
Keywords
Mining-industry; Underground-mining; Coal-mining; Coal-miners; Mathematical-models; Longwall-mining
Contact
Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
Publication Date
19930101
Document Type
Report of Investigations
Fiscal Year
1993
NTIS Accession No.
PB93-198034
NTIS Price
A03
Identifying No.
RI-9458
NIOSH Division
PRC
Source Name
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9458
State
PA
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