Post-Failure Behavior of Two Mine Pillars Confined with Backfill

Details

• Personal Author:
  Seymour, Joseph B. ; Tesarik, Douglas R. ; Yanske TR
• Description:
  Researchers from the National Institute for Occupational Safety and Health used a series of instruments (borehole extensometers, earth pressure cells, and embedment strain gauges) to study the post-failure behavior of two pillars confined by backfill in a test section at the Buick Mine near Boss, Missouri, USA. Evaluation of these pillars was part of a research project to assess the safety of the test section when high-grade support pillars were mined. Data from borehole extensometers installed in several backfill-confined pillars and numerical modeling indicated that these pillars failed during extraction of the support pillars. Failure was corroborated by the post-yield pillar strain response in which the immediate elastic strain was negligible compared to the time-dependent strain component measured between blasting rounds. A three-dimensional, finite-element program with an elastic perfectly plastic material model was calibrated using extensometer data to estimate rock mass modulus and unconfined compressive strength. The resulting rock mass modulus was 45-60% of the average deformation modulus obtained from laboratory tests, and the calibrated compressive strength was 40% of average laboratory values. A rock mass modulus equal to 52% of the average laboratory deformation modulus was calculated using the rock mass rating (RMR) system. Rock mass strength was calculated with the generalized Hoek-Brown failure criterion for jointed rock and indicated that in situ strength was 33% of laboratory strength. Post-failure stresses calculated by the finite-element model were larger for confined pillars than post-failure stresses in unconfined pillars calculated using empirical plots. Data from the calibrated model provided a strain-hardening stress-versus-strain relationship. This knowledge is critical for the design of mines that use partially failed pillars to carry overburden load. [Description provided by NIOSH]
• Subjects:
  Laboratories Mining Occupational Exposure Occupational Health Safety Software
• Keywords:
  Computer-models Ground-control Ground-stability Hazards Laboratory-testing Mining-industry Models Occupational-hazards Rock-bursts
• Series:
  Mining Publications
• ISSN:
  1365-1609
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 10 ; Washington
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  SRL - Spokane Research Laboratory
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  221-232
• Volume:
  40
• Issue:
  2
• NIOSHTIC Number:
  nn:20024126
• Citation:
  Int J Rock Mech Min Sci 2003 Feb; 40(2):221-232
• Contact Point Address:
  NIOSH-Spokane Research Laboratory, 315 E. Montgomery Avenue, Spokane, WA 99207, USA
• Email:
  det4@cdc.gov
• Federal Fiscal Year:
  2003
• Peer Reviewed:
  True
• Source Full Name:
  International Journal of Rock Mechanics and Mining Sciences
• End Date:
  20070930
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:5bf722d9cbdd2d4ef1b6d1785bf567fbe21e35db4d88be1114de882f3b1cbe56059dfe354c2a58db809f6fd58223913062768d0a9c47701cf61f0909477d3698
• Download URL:
  https://stacks.cdc.gov/view/cdc/220752/cdc_220752_DS1.pdf
• File Type:
  [PDF - 731.95 KB ]