Coal Pillar Design Criteria for Surface Protection

摘要

Large areas of ground are permanently supported on coal pillars, both inrnextensive old workings and current drivages in active mining operations.rnContinued growth of civil infrastructure is resulting in more surfacerndevelopment above old bord and pillar mines and an increased need forrnmine development beneath existing surface structures and features. Thernresult is a greater likelihood of conflict between miners, developers andrnregulatory bodies.rnHowever, over the last 40 years there has also been significantrnimprovement in the general level of understanding of pillar behaviour andrnstability, both in Australia and overseas. This paper examines some of thernissues to be considered when undermining surface structures orrnundertaking surface development above old workings.rnThe Factor of Safety (FoS) methodology widely employed for thernassessment of pillar stability is reviewed, including the key geometrical,rngeological and statistical concepts associated with the probability of pillarrnfailure; local and international experiences are examined and significantrnparameters isolated. Common concerns are addressed in the context ofrnactual practical experience, utilising a risk management approach. Recentrnadvances in methods for the assessment of pillar stability are put forward,rnalong with criteria for arriving at rational design outcomes.