A numerical-model-based approach was recently developed by researchers at the National Institute for Occupational Safety and Health (NIOSH) for estimating the changes in both the horizontal and vertical loading conditions induced by an approaching longwall face. In this approach, a systematic procedure is used to estimate the model’s inputs. Shearing along the bedding planes is modeled with ubiquitous joint elements and interface elements. Coal is modeled with a newly developed coal mass model at NIOSH’s Pittsburgh Mining Research Division (PMRD). The response of the gob is calibrated with back analysis of subsidence data and the results of previously published laboratory tests on rock fragments. The model results were verified with the subsidence and stress data recently collected by PMRD from a longwall mine in the eastern United States, and with published cases studies from both eastern and western U.S. mines.

This content is only available via PDF.
You can access this article if you purchase or spend a download.