Regression Analysis and Neural Network Fitting of Rock Mass Classification Systems

Abstract

Commonly used rock mass classification systems, Rock Mass Rating (RMR), Q-System, and Geological Strength Index (GSI) were used as input for simple regression and Neural-Network fitting. The relationship between the classification systems can be used for the estimation of unknown classification ratings. The necessary data for this study, consisting of 250 sets of rock mass classification ratings, were collected from an excavation of an underground mine opening during a time interval of more than two years. The rock mass data belongs to the Pliocene-aged Deniş formation in Soma region of Manisa/Turkey. The ratings, basic and adjusted RMR, Q, Q', and GSI were chosen for the simple regression. Three of the equations are suggested to be taken into account due to their strong correlation of determination. These equations can be utilized especially if the rating Q is known and the adjusted RMR is intended to be estimated. Additionally, basic RMR rating can be estimated by considering the GSI as an input. Utilization of the Neural Networks resulted in an improved prediction capability with a greater predicted-measured coefficient of determination. Implementing the Neural Network fitting also overcame the scatter observed in the regression analysis.