Numerical Modeling for Yield Pillar Design: A Case Study

Two single-entry gateroad systems employing a yield pillar for bump control in a Chinese coal mine were introduced. The overburden depth of the longwall panels was approximately 390 m. When the width/height (W/H) ratio of the yield pillar was 2.67, coal bumps in the tailgate occurred in front of the...

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Bibliographic Details
Published in:Rock mechanics and rock engineering 2015-01, Vol.48 (1), p.305-318
Main Authors: Li, Wenfeng, Bai, Jianbiao, Peng, Syd, Wang, Xiangyu, Xu, Ying
Format: Article
Language:English
Subjects:
Civil Engineering
Coal
Coal mines
Coal mining
Design
Design engineering
Earth and Environmental Science
Earth Sciences
Geophysics/Geodesy
Instrumentation
Joint strength
Longwall
Mathematical models
Original Paper
Overburden
Panels
Rock
Rocks
Shear stress
Shear tests
Strain hardening
Stress analysis
Yield
Yield pillars
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Summary:Two single-entry gateroad systems employing a yield pillar for bump control in a Chinese coal mine were introduced. The overburden depth of the longwall panels was approximately 390 m. When the width/height (W/H) ratio of the yield pillar was 2.67, coal bumps in the tailgate occurred in front of the longwall retreating face. However, in another panel, the coal bump was eliminated because the W/H ratio was reduced to 1.67. Under this condition, instrumentation results indicated that the roof-to-floor and rib-to-rib convergences reached 1,050 and 790 mm, respectively, during longwall retreat. The numerical model was used to back-analyze the two cases of yield pillar application in the hope to find the principle for yield pillar design. In order to improve the reliability of the numerical model, the strain-hardening gob and strain-softening pillar materials were meticulously calibrated, and the coal/rock interface strength was determined by laboratory direct shear tests. The results of the validated model indicate that if the W/H ratio of the yield pillar equals 1.67, the peak vertical stress in the panel rib (37.7 MPa) is much larger than that in the yield pillar (21.1 MPa); however, the peak vertical stress in the panel rib (30.87 MPa) is smaller than that in the yield pillar (36 MPa) when the W/H ratio of yield pillar is 2.67. These findings may be helpful to the design of yield pillars for bump control.
ISSN:0723-2632
1434-453X
DOI:10.1007/s00603-013-0539-8