No abstract

No abstract

The Grace Mine, located in southeastern Pennsylvania, USA, was owned and operated by Bethlehem Steel Corporation during 1951 During this time, iron ore was extracted using the underground panel caving mining method that has resulted in significant surface subsidence. Upon recovery of the water table after mining, a lake has formed over much of the subsided area. Before redevelopment of the abandoned mine site for residential and light industrial usage, an investigation of the subsidence zone of influence, and the potential for further subsidence has been undertaken.

Based on the successful initiation and breakthrough to surface of the PC1 cave at Cadia East, a back-analysis of the performance was conducted to confirm design parameters to optimise the future draw strategy. A mine-scale numerical model was developed to calibrate the existing caving and subsidence behaviour associated with the initiation of PC1 and development of the crater. The successful calibration of historical conditions has provided significant confidence in the caving and subsidence predictions associated with future draw strategies. It has also validated a methodology to simulate the effects of preconditioning in large-scale models.