| Summary: | Spalling of pillar ribs has been a major hazard in the mining industry for decades. In the absence of rib support guidelines, accidents have continued to occur in recent years. Developing effective support guidelines requires a complete understanding of complex pillar damage mechanisms. Continuum models represent a convenient tool for analyzing this problem, but the behavior of such models is dependent of the choice of the constitutive model. In this study, a recently proposed constitutive model was used to simulate the rib fracturing process in a longwall chain pillar at West Cliff mine. After calibration, the model was able to capture the rib displacement profiles for multiple locations of the longwall face and the stress evolution 4 m into the pillar. The rib bolts in the model were found to be yielding over 60% of their length under the headgate loading condition. The model also predicted a steady damage accumulation in the rib for certain face locations, which is consistent with the description of the rib at the site. Damage was localized along the upper part of the pillar and underscored the role that the dirt band played in controlling rib deterioration at the site. The ability of the numerical model to replicate field measurements provides confidence in the capabilities of the new constitutive model. Finally, the need of using multi-point calibration is highlighted by comparing the results of the calibrated model to an alternative model calibrated to a smaller amount of data.
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