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Using a Computer Spreadsheet to Characterize Rock Masses Prior to Subsidence Prediction and Numerical Analysis.


PB96139241

Publication Date 1996
Personal Author O'Connor, K. M.; Siekmeier, J. A.; Powell, L. R.
Page Count 75
Abstract To characterize rock mass overlying high-extraction coal mines, the USBM utilizes a computer spreadsheet program and modified Rock Mass Rating (RMR) system. The spreadsheet calculates an RMR based on a bed's engineering properties determined from core logs and laboratory tests. An in situ deformation modulus and a bending stiffness are computed for each bed. Stiffness-versus-depth plots identify groups of beds with similar stiffness. Large variations in stiffness between adjacent beds are considered significant horizontal discontinuities where slip is likely. Time domain reflectometry (TDR) is used to verify this hypthesis by measuring shear displacement along such discontinuities. A model of the overburden is built by assuming that a near-surface laminated beam exists above a transition zone in which large plastic slip occurs along horizontal discontinuities. Increasingly thicker groups of beds are modeled to determine the most probable beam thickness based on a comparison with measured deflection profiles.
Keywords
  • Ground subsidence
  • Underground mining
  • Rock mechanics
  • Deformation
  • Coal mines
  • Overburden
  • Mechanical properties
  • Site characterization
  • Discontinuities
  • Geologic structures
  • Geologic strata
  • Deflection
  • Stiffness
  • Computer applications
  • Numerical analysis
  • Time domain
Source Agency
  • Bureau of Mines
NTIS Subject Category
  • 48A - Mineral Industries
  • 50D - Soil & Rock Mechanics
Corporate Authors Bureau of Mines, Minneapolis, MN. Twin Cities Research Center.
Document Type Technical Report
Title Note Rept. of investigations/1996.
NTIS Issue Number 199608
Using a Computer Spreadsheet to Characterize Rock Masses Prior to Subsidence Prediction and Numerical Analysis.
Using a Computer Spreadsheet to Characterize Rock Masses Prior to Subsidence Prediction and Numerical Analysis.
PB96139241

  • Ground subsidence
  • Underground mining
  • Rock mechanics
  • Deformation
  • Coal mines
  • Overburden
  • Mechanical properties
  • Site characterization
  • Discontinuities
  • Geologic structures
  • Geologic strata
  • Deflection
  • Stiffness
  • Computer applications
  • Numerical analysis
  • Time domain
  • Bureau of Mines
  • 48A - Mineral Industries
  • 50D - Soil & Rock Mechanics
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