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:
  Roof stability in the belt entry is critical for safe and continuous production of coal during longwall mining. Previous studies of roof falls that occurred in belt entries have shown that the roof falls were largely associated with high in situ and longwall-induced horizontal stresses. To properly support the roof in a belt entry, it is important to understand how longwall-induced horizontal stress changes can affect roof stability in the belt entry. Monitoring of horizontal stress changes was conducted in the belt entries of two Pittsburgh seam longwall panels oriented unfavorably to the major horizontal stress. Numerical models were also set up to investigate how horizontal stress concentrates and relieves in the belt-entry roof near the face as panel orientation changes. Both measurements and modeling results show that high horizontal stress concentrates in the belt entry roof within about 15 m outby the face. The study demonstrates that longwall-induced differential horizontal stress can be used to evaluate the horizontal stress concentration factors. The horizontal stress concentration factors change with panel orientation, resulting in high stress concentrations at orientations between 20 and 110 degrees and low stress concentrations between 130 and 180 degrees. Roof support strategies are given for the belt entries under the influence of high horizontal stress. For unfavorably oriented panels in weak roof conditions, supplementary support should be installed during development, and cable bolts should be anchored into a stable roof horizon. The bolting pattern should be designed to cover both entry corners and the entry center to prevent potential roof cutters and sagging. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety
• Keywords:
  Author Keywords: Roof Stability Belt Entries Ground Control Horizontal Stress Longwall Mining Rock Mechanics Underground Mines
• Series:
  Mining Publications
• ISSN:
  0026-5187
• Document Type:
  Text
• Genre:
  Abstract or Summary
• 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
• Pages in Document:
  41-43
• Volume:
  75
• Issue:
  1
• NIOSHTIC Number:
  nn:20066797
• Citation:
  Min Eng 2023 Jan; 75(1):41-43
• Email:
  nmb2@cdc.gov
• Federal Fiscal Year:
  2023
• NORA Priority Area:
  Mining
• Peer Reviewed:
  True
• Source Full Name:
  Mining Engineering
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:7227ba60ea6028f8fbfdffcc5fabd765d99913e957bc6e5a2a55d1f4bac46d8d903df68fd2d9a4a409311b82d06b29419c44c50fb14118dc22d3b5ec0396b343
• Download URL:
  https://stacks.cdc.gov/view/cdc/215590/cdc_215590_DS1.pdf
• File Type:
  [PDF - 730.37 KB ]