Mining Publication: Design Methods to Control Violent Pillar Failures in Room-and-Pillar Mines

• Mine design
• Pillar design

The sudden, violent collapse of large areas of room-and-pillar mines poses a special hazard for miners and mine operators. This type of failure, termed a ‘cascading pillar failure' (CPF), occurs when one pillar in a mine layout falls, transferring its load to neighboring pillars, which causes them to fail, and so forth. Recent examples of this kind of failure in coal, metal and non-metal mines in the U.S.A. are documented. Mining engineers can limit the danger presented by these failures through improved mine design practices. Whether failure occurs in a slow, non-violent manner or in a rapid, violent manner is governed by the local mine stiffness stability criterion. This stability criterion is used as the basis for three design approaches to control cascading pillar failure in room-and-pillar mines the containment approach, the prevention approach and the full extraction mining approach. These design approaches are illustrated with practical examples for coal mining at shallow depth.