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Loading Characteristics of Pillars in Multiple-seam Mining Operations.

Authors
Chekan-GJ; Matetic-RJ
Source
MISSING :19 pages
Link
NIOSHTIC No.
10006172
Abstract
The Bureau of Mines, in an effort to improve resource conservation, mine planning, and development, is currently investigating the loading behavior of pillars in multiple-seam developments. The simultaneous mining of two or more coalbeds may cause instability between room-and-pillar operations, resulting in an interaction known as pillar load transfer. Although pillars may be adequately designed for single-seam mining, the development of a second seam may complicate loading conditions in both operations. If pillars are not adequately designed to contend with this load transfer, failure of the mine structure may result. To improve multiple-seam development and pillar design, the Bureau studied the loading characteristics of pillars in three separate multiple-seam operations. In all three cases, instrumented pillars recorded increasing pressure after development of the second seam. Increases in the average pillar pressure ranged from 7 to 110 pct over predicted overburden loads. An analysis of pillar loading before and after second-seam mining indicates that the ratio of overburden to innerburden thickness is a critical factor influencing load transfer. Based on this relationship, safety factors for case study pillars are calculated and alternative design considerations are discussed.
Publication Date
19880101
Document Type
IH; Report of Investigations;
Fiscal Year
1988
NTIS Accession No.
NTIS Price
Identifying No.
RI 9173
NIOSH Division
PRC;
Source Name
MISSING
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