A Case Study of Pillar Collapse at a Limestone Mine in Pennsylvania

Details

• Personal Author:
  Esterhuizen, Gabriel S. ; Murphy MM ; Tyrna PL
• Description:
  The sudden collapse of approximately 3 Ha of room-and-pillar workings at a limestone mine in southwestern Pennsylvania in 2015 resulted in an air-blast that injured three mine workers. Subsequent investigations showed that an area encompassing 35 pillars had collapsed. The pillars were 9 to 10 m wide and up to 18 m high. A notable geologic feature is the through-going joints that dip at 50 degrees to 80 degrees and can extend from the roof to the floor of the pillars. These structures are thought to have weakened the pillars well below the strength that is predicted by empirical equations for hard-rock pillar design. This paper presents the relevant geotechnical data related to the collapsed area and numerical model results that were used to estimate the pillar loading underneath the variable topography and compares the pillar loads to some established hard-rock pillar strength equations. The outcome is also compared to a strength equation that was developed specifically for limestone mines in which the negative impact of large angular discontinuities is explicitly accounted for. The results show that the critical state of the workings would have been predicted correctly by the limestone pillar strength equation. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety
• Keywords:
  3D Compressive Strength Environmental Stress Failure Analysis Geologic Models Geologic Structures Geostatistics Geotechnical Engineering Ground Control Ground Stability Hard Rock Mines Horizontal Stress Limestone Mines Mathematical Models Pillar Design Pillar Mechanics Rock Mechanics Roof Falls Roof Supports Room And Pillar Mining Stone Mines Stress Analysis Structural Analysis Structural Failure Subsidence Three Dimensional Topography Underground Mines

  More +
• Series:
  Mining Publications
• Publisher:
  American Rock Mechanics Association (ARMA)
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  OSHA Region 10 ; OSHA Region 3 ; Pennsylvania ; Washington ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• NIOSHTIC Number:
  nn:20053061
• Citation:
  52nd US Rock Mechanics/Geomechanics Symposium, June 17-20, 2018, Seattle, Washington. Alexandria, VA: American Rock Mechanics Association (ARMA), 2018 Jun; :ARMA 18-363
• Contact Point Address:
  G. S. Esterhuizen, NIOSH Pittsburgh Mining Research Division, Pittsburgh, PA, USA
• CAS Registry Number:
  Limestone (CAS RN 1317-65-3)
• Federal Fiscal Year:
  2018
• NORA Priority Area:
  Mining
• Peer Reviewed:
  False
• Source Full Name:
  52nd US Rock Mechanics/Geomechanics Symposium, June 17-20, 2018, Seattle, Washington
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:1fbbae5e5b440bd725ec4ab491a1beadc40c72e5de3f6575753e9fd78a360f0e330556f7941d01596e69244091181833e5dfc894e6de484de50cbf6f96d689df
• Download URL:
  https://stacks.cdc.gov/view/cdc/227732/cdc_227732_DS1.pdf
• File Type:
  [PDF - 1.51 MB ]