The Prediction and Occurrence of Chimney Subsidence in Southwestern Pennsylvania

Coal mining in Pennsylvania has long been an important factor in the economic development of the commonwealth. However, the mines abandoned before today's strict environmental regulations have degraded over half of Pennsylvania's counties. Subsidence incidents, known as chimney caves, are in the form of sinkholes and develop above abandoned room-and-pillar mines. Chimney caving is the most dominant type of subsidence in southwestern Pennsylvania, yet there are no accurate means available to predict their occurrences. Therefore, an investigation has been conducted in order to develop a set of engineering criteria, or an equation, to predict such occurrences. Through conducting sand model experiments and through the collection of a chimney subsidence incident database, such an equation was derived, and verified using actual field data.