Correlation Between RMR and GSI at the Rukoh Dam Suppletion Tunnel, Aceh Province, Indonesia

Accuracy and precision in assessing the rock mass quality were crucial aspects of tunnel construction. The quality of the rock mass had a significant impact on the tunnel's stability and support system. The Rock Mass Rating (RMR) and Geological Strength Index (GSI) methodologies were linearly related. Consequently, the proposed equation derived from correlation among rock mass quality methods was an effective and efficient solution to determine rock mass quality quickly. This research aimed to establish a RMR-GSI correlation equation in the Rukoh Dam Suppletion Tunnel, Aceh, Indonesia. This research methodologies also compared statistical relationships between several RMR-GSI correlations from previous studies in order to produce a proposed equation. The rocks at the tunnel site were poor calcareous siltstone. The proposed equation, which comes from statistical data processing of drilling results, evaluated based on deveral approaches, including R-Correlation, Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Root Mean Square Error (RMSE). R-Correlation is 0.96, MAE is 2.62, MAPE is 0.09, and RMSE is 3.25 for this proposed equation. The evaluation results indicated that this equation is more precise than the other equations. The significance of this research was to simplify the procedure for converting between RMR and GSI methods for determining rock mass quality. Therefore, this equation provided a shortcut to analyzing rock mass quality, especially in calcareous siltstone rock formations.