Numerical modeling of yielding chain pillars in longwall mines.
Badr-S; Schissler-A; Salamon-M; Ozbay-U
NARMS-TAC 2002, "Mining and Tunnelling Innovation and Opportunity," Proceedings of the 5th American Rock Mechanics Symposium and the 17th Tunnelling Association of Canada Conference, July 7-10, 2002, Toronto, Ontario, Canada. Hammah R, Bawden W, Curran J, Telesnicki M, eds., Toronto, Ontario, Canada: University of Toronto Press, 2002 Jul; 1:99-106
The practice in thick seam longwall mining at depths of 500 m and more shows that considerable sloughing of chain pillars, sometimes accompanied by bumps, may occur during development stage. The ability of these pillars to continue functioning as roof support during development and long walling stages has to be assured for a safe and economical mining operation. Although already being used, little is known quantitatively about the response of these "yielding" chain pillars to varying loading conditions that come about during different stages of longwall mining. The paper presents the results from case history reviews and numerical modeling studies performed with the objective of improving the understanding of yield pillar behavior. The case history review indicates that yield pillars with width:height ratios 3 to 6 performed satisfactorily. The numerical modeling studies using a three-dimensional finite difference code FLAC3D  allowed realistic simulations of complex mining geofiletries and loading conditions of longwall mining. The numerical model incorporates a strain-softening constitutive model for post-peak pillar behavior and a non-linearly elastic material behavior for sin1ulating gob compaction. The differences in performance of pillars with strain softening material and traditional Mohr-Coulomb material are also highlighted.
Mining-industry; Underground-mining; Mine-shafts; Models; Longwall-mining; Room-and-pillar-mining
Conference/Symposia Proceedings; Book or book chapter
Hammah-R; Bawden-W; Curran-J; Telesnicki-M
NARMS-TAC 2002, "Mining and Tunnelling Innovation and Opportunity," Proceedings of the 5th American Rock Mechanics Symposium and the 17th Tunnelling Association of Canada Conference, July 7-10, 2002, Toronto, Ontario, Canada
Colorado School of Mines