ABSTRACT
In room and pillar coal mining, violent coal bumps can occur during the retreat mining phase when stress levels in pillars adjacent to the gob area reach their maximum. Proper mining sequences can decrease the risk of bumps. This paper describes a non-linear boundary element program, MULSIM/NL, used to evaluate cut sequences for retreat mining that decrease the coal bump risk.
Program MULSIM/NL features six material types (linear and nonlinear) and an energy subroutine to obtain energy release rate (ERR) values for a mining sequence. The ERR gauges the coal bump risk and the relative desirability of different mining sequences. ERR studies with MULSIM/NL suggest the Olga Mine method’s superiority for retreat mining in bump prone conditions over other methods such as single split and fender, pocket and wing or open ending.
