TITLE:
Countermeasure Method for Stope Instability in Crown Pillar Area of Cut and Fill Underground Mine
AUTHORS:
Tri Karian, Hideki Shimada, Takashi Sasaoka, Sugeng Wahyudi, Deyu Qian, Budi Sulistianto
KEYWORDS:
Crown Pillar, Stope Stability, Active and Passive Type Support System, Sill Pillar, Surface Pile
JOURNAL NAME:
International Journal of Geosciences,
Vol.7 No.3,
March
17,
2016
ABSTRACT: Maintaining stability as
well as optimizing recovery of crown pillar, a pillar separating surface area
with the uppermost stope in overhand cut and fill underground mining method, is
important. Failures in stope may lead to crown pillar failures and cause
surface subsidence. Increasing crown pillar thickness will increase crown
pillar stability yet reduce mining recovery because part of crown pillar is
formed by ore body. Preventing stope failure is the key to maintain stability
and optimize recovery of crown pillar. Therefore, it is important to study
countermeasure method for stope failure especially in crown pillar area. An
attempt has been made to investigate the effectiveness of various
countermeasures for stope failure in crown pillar area by means of parametric
study. The result shows active type support system is effective for supporting
stope in high vertical stress condition while the passive one needs to be
installed if the stope is opened in high horizontal stress condition. In
general, more supporting capacity from both type support systems is needed if
the stope is opened in more severe geological condition. Another
countermeasures, sill pillar and surface pile, are introduced for stope
instability in crown pillar and non-crown pillar area. Sill pillar is an
abandoned slice of unstable stope based on stability analysis. Sill pillar is
very effective to stabilize stope both in crown pillar and non-crown pillar
area, especially for stope in high horizontal stress condition. Sill pillar
application in model with stress ratio 2 can optimize 20 meter thickness of
crown pillar into 5 meter. Another proposed countermeasure is surface pile.
Surface pile can be installed from the surface to improve stability of crown
pillar and stope. The most effective use of surface pile is found in simulation
of model with stress ratio 0.75 where surface pile can optimize 15 meter
thickness of crown pillar into 5 meter.