Estimating strength of rock masses using fuzzy inference system

This paper describes how to apply fuzzy inference system (FIS) to estimate the strength of field scale rock masses by judgment and experience of practicing engineers. Three important parameters believed to influence the rock mass behavior namely intact rock strength, block size, and joint surface condition are defined as fuzzy variables. The strength of jointed rock masses is then estimated by incorporating different combinations of three fuzzy inputs into Mamdani rule-based FIS model. To validate the accuracy of the model results, a comprehensive rock mass data is collected from the literature and the strength of rock masses estimated using different empirical equations is compared to the strength of rock masses estimated from the FIS model. It is concluded that the newly developed model compares well with the estimated results and it can be recommended as an alternative method for the rock mass strength predictions instead of empirical approaches in practice.