29th International Conference on Ground Control in Mining

The Analysis of Retreat Mining Pillar Stability (ARMPS) and the LaModel programs have been used successfully in the U.S. for designing safe pillar recovery operations for many years. However, the recent Crandall Canyon Mine collapse showed that further research is required to improve the pillar design for recovery under deep cover. To this end, the National Institute for Occupational Safety and Health (NIOSH) and the West Virginia University (WVU) Mining Engineering Department have been working together to improve both the ARMPS and the LaModel programs. This paper compares and analyzes the overburden loads calculated by ARMPS 2002, the new ARMPS 2010, and the LaModel program with regard to the retreat pillar line, the gob, and the barrier pillars. The analysis shows a number of distinct differences between the ARMPS and LaModel loading distributions. Ultimately, the programs, with their distinctive load distributions, are used to analyze a database of 52 deep cover pillar retreat case studies, and the ability of each program to discriminate between successful and unsuccessful retreat pillar plans is evaluated.