Three-dimensional FEM was used to simulate the mining operations and to estimate average pillar compressive stress at each operation step.
A method of estimating the pillar strength and selecting a safety factor for design was developed based on observations of stable and failed pillars, supplemented by numerical models.
Such significant differences in confining stresses are not taken into account when estimating peak pillar strength using most common empirical techniques such as those proposed by Bieniawski and Salamon.
While using lower pillar strength estimates may be considered conservative, it underestimates the actual capacity of pillars in accumulating much higher stress and strain energies, misleading the designer and inadvertently diminishing mine safety.
The Estimate also raises doubts about the pillar of the Administration's strategy, the training and equipping of about three hundred and fifty thousand Afghan military forces and police.
It has been shown that coal pillar strength can be estimated from the attributes of effective width and height, however the risk for pillar panel failure resulting in surface subsidence cannot be estimated by consideration of individual pillars in isolation.
For the purpose of numerical modeling, the Hoek-Brown failure criterion was used to estimate the safety factor of the coal pillar.
The observations developed in this paper are intended to provide researchers and mining engineers with initial estimate of the burst risk of coal pillar, as the study of bursting liability is of importance in forecasting and preventing the bump of coal pillar.
The stand-up time of a room and pillar mining panel is also estimated based on the modified Q-system.
