Application of rock mass classification system for the stability of underground limestone mines

Rock mass classification systems, with suitable modifications, serve as a simple empirical approach for the design of various underground mine structures. Rock mass classification methods such as RMR, Q system and GSI have been widely adopted with certain modifications for the design of mine openings. One of the objectives of the classification systems for a engineering has been to make it simple to use as a preliminary design tool for underground mine structures. A detailed surveying for GSI mapping as well as for calculating RMR values was undertaken at Daesung and Pyunghae underground limestone mining sites in Korea. From the joint survey data safe unsupported span was estimated using RMR, Q systems while GSI was used to estimated the rock mass strength conditions. Based on GSI values and intact rock strength properties, the rock mass strength, modulus of elasticity as well as the Mohr-Coulomb strength parameter were determined. A comparative study was drawn to underline the scope and limitations of each of the above classification systems.