Underground coal mine ground control persists as a unique challenge in rock mass engineering. Fall of roof and rib continue to present a hazard to underground personnel. Stability of underground openings is a prerequisite for successful underground coal mine workings. An adaptation of a civil engineering design standard for analyzing the stability of underground excavations for mining geometries is given here. The ground response curve--developed over seventy years ago for assessing tunnel stability--has significant implications for the design of underground excavations, but has seen little use in complex mining applications.

The interaction between the small scale (pillar stress-strain) and the large scale (ground response curve) is studied. Further analysis between these two length scales is conducted to estimate the stress on pillars in a room-and-pillar coal mine. These studies are performed in FLAC3D by implementing a two-scale, two-step approach. This two-scale approach allows for the interaction between the small, pillar scale and the large, panel scale to be studied in a computationally efficient manner.