A new approach for estimation of the rock mass deformation modulus: a rock engineering systems-based model

Abstract

The deformation modulus of a rock mass is one of the crucial parameters used in the design of surface and underground rock engineering structures. Due to the problems in determining the deformability of jointed rock masses at the laboratory scale, various in-situ test methods have been developed. Although these methods are currently the best techniques, they are expensive and time-consuming, and present operational problems. To overcome this difficulty, in this paper, based on the basic concepts of a rock engineering systems (RES) approach, a new model for the prediction of the deformation modulus of a rock mass is presented. The newly proposed approach involves seven effective parameters (depth, rock quality designation, uniaxial compressive strength, the discontinuity density, the condition of discontinuities, the groundwater condition, and an adjustment for the orientation of discontinuities) pertinent to the deformation modulus of a rock mass, yet keeping simplicity as well. The performance of the RES model is compared with multiple regression models. The estimation abilities offered using RES and multiple regression models were presented by using field data obtained from road and railway construction sites in Korea. The results achieved indicate that the RES-based model predictor with the least mean square error and a higher coefficient of determination (R 2) performs better than the multiple regression models.