Effects of Specimen Age on the Uniaxial Compressive Strength and Moisture Content of Weak Coal Measure Rocks

Details

• Personal Author:
  Barton, Timothy M. ; Bhatt, Suresh K. ; Mark C ; Molinda, Gregory M.
• Description:
  The uniaxial compressive strength (UCS) is the most fundamental measurement used in geotechnical rock characterization for mine design. While there are standardized procedures for how to conduct UCS tests, there are no firm guidelines as to when to conduct them. However, it is well known that the strengths of at least some rocks can change during the time between when the core first comes up out of the hole and when it is prepared and tested in the lab. The goal of this NIOSH (National Institute for Occupational Safety and Health) study was to evaluate UCS changes occurring in a broad range of weak coal measure rocks over a one-year time span. The study found the highest moisture contents were measured when the core was fresh, immediately after it was taken from the hole. The specimens then dried rapidly over the next few weeks. Subsequently, sample moisture contents decreased slightly in the winter and increased in the summer in response to the ambient changes in humidity. The measured UCS of the core also changed during the year, apparently in response to changes in the moisture content. The UCS values from the dry, winter months were, on average, 60% higher than the values obtained when the core was fresh, and the summer UCS was approximately 11% lower than the winter UCS. These findings have implications for the use of UCS as an input parameter for both empirical and numerical mine design methods. UCS values of unprotected core tested weeks to months after drilling can be significantly stronger and indicate stronger roof sequences than warranted. In order to obtain the most representative and reliable UCS value, it is necessary to test the core, or wrap and seal it, at the drill site shortly after recovery. [Description provided by NIOSH]
• Subjects:
  Mining Occupational Health Safety
• Keywords:
  Analytical-processes Ground-control Ground-stability Mining-industry Underground-mining
• Series:
  Mining Publications
• ISBN:
  9780978938338
• Publisher:
  West Virginia University
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  OSHA Region 3 ; Pennsylvania ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PRL - Pittsburgh Research Laboratory
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  332-337
• NIOSHTIC Number:
  nn:20034277
• Citation:
  Proceedings of the 27th International Conference on Ground Control in Mining, July 29-31, 2008, Morgantown, West Virginia. Peng SS, Mark C, Finfinger GL, Tadolini SC, Khair AW, Heasley KA, Luo Y, eds. Morgantown, WV: West Virginia University, 2008 Jul; :332-337
• Editor(s):
  Peng SS; Mark C; Finfinger GL; Tadolini SC; Khair AW; Heasley KA; Luo Y
• Federal Fiscal Year:
  2008
• NORA Priority Area:
  Mining
• Peer Reviewed:
  False
• Source Full Name:
  Proceedings of the 27th International Conference on Ground Control in Mining, July 29-31, 2008, Morgantown, West Virginia
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:3cd828ebcdaf550828ffa7769c84b095bd18f8b81ab3c030545b7038e6dcd2e7e01e993c635c38851bea63e780ac9ab30143a1d92d66861d1e35a5cac43616c2
• Download URL:
  https://stacks.cdc.gov/view/cdc/226989/cdc_226989_DS1.pdf
• File Type:
  [PDF - 783.85 KB ]