The paper provides new results on the fracture surface roughness testing from the Bátaapáti National Radioactive Waste Repository project. During the calibration of modeling and design work it was necessary to develop a simple and quantitative approach to predict the Joint Roughness Coefficient (JRC) value of fracture surfaces. To reach this goal laboratory-scale and on-site large scale surfaces were investigated. The roughness was studied on 15 smaller samples (average area of 73 cm2), and on 5 larger in-situ granitic surfaces. The latter were documented during the excavation of the repository chambers (average area of 12m2). Additional specimens (more than 40) that were used for direct shear strength test (average area of 26 cm2) were also studied by generating 3D models with the software JointMetrix3D (JMX). In order to determine the shear strength numerically, the JRC value of the surface is one of the key influencing factors. The roughness parameter (Rp) and the roughness parameter of the surface (Rs) can be calculated using several 2D profiles of the surfaces tested. The JRC values were calculated from the results of the shear strength test, and compared with the JRC values calculated from Rs. The resulting JRC values served as an input parameter to the original equation of Barton. From the evaluation of the relationship between JRC and Rs a new correlation were identified, which provided a better estimation of the JRC values of the rock types tested. The following correlations were found:


The models were built in JointMetriX3D from the surfaces that were measured both in 2D (JMX profiling) and in 3D, with the Ogre Project software. Unfortunately the 3D roughness profiling did not provide a reliable approximation therefore further studies are necessary in order to determine additional equations.

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