Roof Stability and Support Strategies Associated with Longwall-Induced Horizontal Stress Changes in Belt Entries

Details

• Personal Author:
  Esterhuizen, Gabriel S. ; Minoski T ; Sears M ; Trackemas J ; Tulu B ; Zhang P
• Description:
  Longwall mining is a highly productive and effcient coal mining method used in the USA. During longwall retreating, the belt entry must be maintained stable, and any roof fall in the belt entry would jeopardize mine safety and substantially interrupt the continuous production of coal in the longwall face. Past experience of longwall mining has shown that belt entry stability was the greatest challenge in longwall ground control, and the occurrence of roof falls in belt entries was largely associated with high horizontal stress. To properly support the roof in the belt entry, it is important to understand how longwall-induced horizontal stress changes afect roof stability in belt entries and to strategically install supplementary support to prevent any potential roof falls. Researchers from the National Institute for Occupational Safety and Health (NIOSH) performed horizontal stress measurements in the immediate roof of the belt entries for two Pittsburgh seam longwall panels oriented unfavorably to high horizontal stress. Hollow inclusion cells (HICells) were installed in the immediate roof at the intersection in each of the belt entries, and stress changes were monitored as the longwall face was approaching and passing the intersection. Numerical models were set up to calculate the longwall-induced horizontal stress changes in the roof at the monitoring sites. With the verifed model, investigations were made of how horizontal stress is concentrated and relieved in the belt entry roof near the face under diferent panel orientations. Both measurements and modeling results showed that high horizontal stress is concentrated in the roof in the belt entry within about 15 m outby the face when a longwall panel is unfavorably oriented to the major horizontal stress. The study demonstrated that longwall-induced diferential horizontal stress can be used as an indication of the degree of horizontal stress concentration. Roof support strategies are discussed on how to maintain the stability of belt entry under high horizontal stress concentration. [Description provided by NIOSH]
• Subjects:
  Coal Coal Mining Geology Mining Occupational Health Safety
• Keywords:
  Author Keywords: Roof Stability Belt Entries Coal Mining Ground Control Ground Monitoring Horizontal Stress Longwall Mining Rock Mechanics Roof Falls Underground Mines
• Series:
  Mining Publications
• ISSN:
  2524-3462
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; Pennsylvania ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  39
• Issue:
  5
• NIOSHTIC Number:
  nn:20065474
• Citation:
  Min Metall Explor 2022 Oct; 39(5):1873-1885
• Contact Point Address:
  Peter Zhang, CDC/NIOSH, Pittsburgh Mining Research Division, Pittsburgh, PA 15236
• Email:
  nmb2@cdc.gov
• Federal Fiscal Year:
  2023
• NORA Priority Area:
  Mining
• Peer Reviewed:
  True
• Source Full Name:
  Mining, Metallurgy & Exploration
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:ac05c9485b4266ca4de816b2c0ad0c52d96e1bacb591c9bd8bbfcb45e829aacda67226221f7674313c14c011b68b6f84522e55982cb2e42232ac09813ffecec5
• Download URL:
  https://stacks.cdc.gov/view/cdc/215569/cdc_215569_DS1.pdf
• File Type:
  [PDF - 2.04 MB ]