Abstract: Numerical models are increasingly used as tools to design support for coal mine entries. A critical part of the design process is to obtain rock strength parameters that are representative of the large-scale rock mass surrounding the excavations. The Coal Mine Roof Rating (CMRR) is a rock classification system that was developed to characterize the bedded strata found in coal mines. Procedures were developed to estimate rock strength properties suitable for numerical modeling based on the CMRR outputs. The rock matrix and bedding strength are quantified separately for the different rock units. The rock units are modeled using the ubiquitous joint approach, accounting for laboratory- to field-scale strength reduction. Contacts between units are modeled as explicit interfaces. Procedures for estimating the bedding cohesion, tensile strength and friction angle from CMRR data are presented. The strength estimation and modeling procedures are calibrated against several field monitoring sites to ensure that realistic results are obtained. Two cases are presented to demonstrate the approach and the match with field monitoring results.
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