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Examining longwall shield failures from an engineering design and operational perspective.

Authors
Barczak-TM
Source
Proceedings: new technology for coal mine roof support. Mark C, Dolinar DR, Tuchman RJ, Barczak TM, Signer SP, Wopat PF, eds. Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication No. 2000-151; (IC 9453), 2000 Oct; :223-245
NIOSHTIC No.
20000890
Abstract
Longwall operators are again pushing the envelope in terms of life expectancy for longwall shields. State-of-the-art shields are now expected to last more than 60,000 loading cycles, twice the life expectancy compared with those of a decade ago. A review of trends in shield design shows that shields continue to increase in both size and capacity. Some state-of-the-art shields now weigh over 30 tons and provide up to 1,200 tons of support capacity. Although life expectancy has increased and modern shields are structurally more reliable, permanent failures do still occur. This paper provided an engineering and operational assessment of shield design and provides key points to observe in what causes premature shield failures. Design practices to improve structural margins of safety that will prevent premature failures from occurring are also examined. A survey of recent shield failures is provided, as well as trends in shield design and how they might impact the performance and longevity of a shield. Hydraulic failures are more common than structural failures. Although hydraulic failures occur on all aging longwall shields, they often go undetected for long periods, resulting in degraded support capacity that can lead to serious ground control problems. The fundamentals of shield hydraulics are described in order to evaluate hydraulic failures that plague all shields at some point in their service life, and practical methods to detect hydraulic failures are examined. The paper concludes with recommendations for inspecting damaged shields and safety precautions regarding their continued use.
Keywords
Coal-mining; Structural-analysis; Performance-capability; Accident-analysis; Accident-potential
Publication Date
20001001
Document Type
Conference/Symposia Proceeedings
Editors
Mark-C; Dolinar-DR; Tuchman-RJ; Barczak-TM; Signer-SP; Wopat-PF
Fiscal Year
2001
NTIS Accession No.
NTIS Price
NIOSH Division
PRL
Source Name
Information Circular 9453 - Proceedings: New technology for Coal Mine Roof Support
State
PA
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