... softening properties at the pillar scale to accommodate an unstable response and match deformations observed at the time of the collapse. Widespread pillar failure is then simulated in a mine scale model using a 2D finite difference software. Calculations of released energy are recorded throughout...

... is a promising approach for analyzing the possibility of violent pillar failure. Typically, the local mine stiffness calculation quantifies the loading stiffness of the surrounding rock mass and compares that to the stiffness of the support pillars in the post-failure range in order to determine if a pillar...

... underground excavations by investigating parameters that could be used to indicate instances of unstable pillar failure. A mechanically coupled discrete element model of coal is utilized to study the effect of geometry and loading system stiffness on pillar failure. First, the coupled model is verified...

... Panel 7 s Measurement position above the panel Fig. 10 Section showing the stress cell position above the pillar (not drawn to scale) After pillar failure and once the stress had dropped to the residual strength of the pillar, a series of stress measurements were made to determine the stress profile...

... hydraulic fracturing variation reservoir geomechanics seismicity Reservoir Characterization stope pillar failure haulage extraction excavation metals & mining strength MPa closure Stability Pillar fracture stress measurement pillar reef mining face tunnel complete...

... the effects of pre-existing discontinuities and propagation of new fractures adjacent to the periphery of the excavation as a result of stress redistribution. Initial modelling has concentrated on simulation of progressive pillar failure, prior to examination of other design applications such as tunnel roof...

... pillar failure by a small amount (approximately 5 percent). Progressive pillar failure is unlikely, because arching transfers most load from yielding pillars to large unmined abutments rather than to the smaller panel pillars. INTRODUCTION Pillar reinforcement by bolting was performed recently...

...- tions by the overcoring technique, and rock mass displacement measurements by means of borehole and tape extensometers. Design data was greatly enhanced by unplanned pillar and roof failures. PILLAR STRENGTH DETERMINATIONS Overcoring measurements were made before, during, and after pillar failures...

... strength reservoir geomechanics pillar failure Rock mechanics example problem stability rock property evaluation Reservoir Characterization Upstream Oil & Gas Salamon laboratory local failure pillar specimen application design method equation safety factor pillar design LIMIT...