Summary
An indication of the complete stress-strain behaviour of coal was obtained through instrumenting a headgate yield pillar and monitoring the changes in vertical and horizontal pillar stress, pillar strain, and roof-floor convergence as a function of time and distance from the moving longwall face. A semiautomated monitoring program was conducted over a 5 month period as the longwall face advanced toward and eventually passed the instrumented pillar. The development of a confined core and yield zone within the pillar was confirmed by the vertical and horizontal stress changes. Thein situ pre-failure (208 to 661 MPa) and post-failure moduli (55 to 208 MPa) of the coal were determined from the change in pillar stress versus pillar strain. Thein situ moduli are an order of magnitude lower than the 3450 MPa, commonly assumed for coal.
Similar content being viewed by others
References
Babcock, C.O. and Bickel, D.L. (1984) Constraint — the missing variable in the coal burst problem, inProceedings of the 25th U.S. Symposium on Rock Mechanics, Northwestern University Chicago, AIME 639–47.
Bieniawski, Z.T. and Mark, C. (1986) Field measurements of chain pillar response to longwall abutment loads, inProceedings of the 5th Conference on Ground Control in Mining (edited by S.S. Peng), West Virginia University, Morgantown, 114–22.
Carr, F. and Wilson, A.H. (1982) A new approach to the design of multi-entry developments for retreat longwall mining, inProceedings of the 2nd Conference on Ground Control in Mining, West Virginia University, Morgantown, 1–21.
Dutta, P.K. (1985) Some recent developments in vibrating wire rock mechanics instrumentation, inProceedings of the 26th Symposium on Rock Mechanics, Rapid City, Balkema, 1043–54.
Dutta, P.K., Hatfield, R.W. and Runstadler, P.W. (1981) Calibration characteristics of the Irad gauge vibrating wire stressmeter at normal and high temperature,Tech Rep 80–2, Lawrence Livermore Laboratory, 106 p.
Guana, M., Price, Kenneth R. and Martin, Eddie (1985) Yield pillar usage in longwall mining at depth — No. 4 Mine, Brookwood, Alabama, inProceedings of the 26th U.S. Symposium on Rock Mechanics, S. Dakota Sch. of Mines, Balkema, 695–702.
Newman, D.A. (1985) The design of coal mine roof support and yielding pillars for longwall mining in the Appalachian coalfield, PhD dissertation, The Pennsylvania State University, 392 p.
Newman, D.A. (1987) Automated monitoring of the stress-strain behavior of a yield pillar, inProceedings of the 5th Annual Workshop VPI Generic Ctr, Tuscaloosa, 47–54.
Pariseau, W.G. and Eitani, I.M. (1977) Post-elastic vibrating wire stress measurements in coal, inProceedings of the International Symposium on Field Measurements in Rock Mechanics, Zurich, Balkema, 255–73.
Park, D.W. and Ash, N.F. (1984) Stability analysis of entries in a deep coal mine using finite element method, inProceedings of the 2nd Conference on the Use of Computers in the Coal Industry.
Serata, S. (1984) Stress control methods: quantitative approach to stabilizing mine openings in weak ground, inProceedings of the 1st International Conference on Stability in Underground Mining, Vancouver (edited by Brawner), AIME, New York, 52–98.
Tanious, N.S. (1987) The use of vibrating wire stressmeters in coal,Preprint No. 87-114, AIME-SME Annual Mtg. Denver, 5 p.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Newman, D.A. In situ yield behaviour of a coal pillar. International Journal of Mining and Geological Engineering 7, 163–170 (1989). https://doi.org/10.1007/BF01554344
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01554344