Civil and Geoengineering Letters Editorial Office info@jcivilgeo.com mEDRA 20260525 DOI Registration 01

06 10.22034/CGEL.3.1.e100058 https://doi.org/10.22034/CGEL.3.1.e100058 Civil and Geoengineering Letters mEDRA 01 01 3115-8129 Civil and Geoengineering Letters Editorial Office IR 01 3115-8129 JB 3 1 01 202605 1 1 A01 Mohammad Jafarian Jafarian, Mohammad Mohammad Jafarian 2 A01 Ebrahim Asghari-Kaljahi Asghari-Kaljahi, Ebrahim Ebrahim Asghari-Kaljahi 01 eng 202605 03 00 The accurate classification of rock masses plays a critical role in the design and safety of geotechnical and tunneling projects. Among the most widely used systems for rock mass characterization are the Geological Strength Index (GSI) and the Rock Mass Quality index (Q-system), both of which integrate various structural and geomechanical parameters. This study focuses on evaluating the empirical relationship between GSI and Q-system in granitic rock masses of the Keno-Kouh region, situated in western Iran. Field investigations were conducted at multiple granite exposures, where joint conditions, discontinuity spacing, roughness, alteration, and rock strength were systematically measured. GSI values were derived from both direct field assessments and estimation charts, while Q-values were calculated using Barton’s classification system. A statistical correlation analysis was performed between GSI and Q-values to identify a mathematical relationship relevant to this specific lithological setting. The findings demonstrate a strong linear correlation (R²>0.85) between the two classification systems within the granitic units, highlighting the isotropic and relatively homogeneous nature of the Keno-Kouh granites. The regression equations developed in this study provide a practical tool for estimating one index based on the other, which can be especially useful in data-limited engineering scenarios. 20 Rock mass; Geological strength index; Q-System; Granite; Keno-Kouh region 01 00 20260225 02 00 20260414 2026 Mohammad Jafarian Ebrahim Asghari-Kaljahi