## 10 Conclusions and Concluding Remarks  
Three Iddefjord granite samples were tested in this research in order to find possible ways to determine the UCS values from triaxial testing. The UCS of the samples were obtained by twenty-eight empirical methods, one ANN-model method, and finally by a triaxial test method. With the triaxial test method, different fitting equations are used, which include linear, parabolic, and Hoek-Brown fitting equations. Based on the results from the test, the following conclusions can be made:  
* UCS estimated with empirical methods resulted in a very large variation. Only two out of twenty-nine empirical methods were able to provide the \"Estimated-UCS\" close to the \"True-UCS\" (within 15% of error). Thus, great care should be given when using empirical formulae for estimating the UCS;
* The \"Estimated-UCS\" based on results from the triaxial test is close to the \"True-UCS\" for all three samples in this research. The behaviour of the rock sample can be observed directly from the test results. Based on the observed behaviour, a proper fitting function (linear or non-linear) can be selected. The reliability of the calculation can also be evaluated based on the value of the coefficient of determination (\(R^{2}\)) of the fitting equations;
* It can be stated that it is a much more reliable way to estimate UCS based on results from the triaxial test Type II than using empirical formulae, as demonstrated herein. With a proper fitting equation used, the error of this method can be less than 2.5%. With such accuracy, UCS can be considered to be an additional relevant outcome of triaxial test Type II;
* The method described herein is not limited to granite as used in this research, rather, it is expected to be a universal tool for all hard rock samples. The limitations in using this method for other rock types are just the same as for performing an ordinary triaxial test Type II. For example, too-brittle rock types are not suitable for triaxial tests as the sample will be broken and completely destroyed at a very early stage of the triaxial test Type II. Otherwise, the estimation of UCS can be calculated as soon as a triaxial test Type II has been performed successfully;
* The approach of determining UCS based on triaxial testing has been demonstrated after successfully applying a triaxial test Type II. This method can be applied for triaxial test Type III. The method might be applied with triaxial test Type I, however, inhomogeneity between rock samples will have a greater impact on the accuracy of the calculation when using results from this test type. As mentioned earlier, this publication is aiming to encourage using fundamental knowledge in rock and soil mechanics to calculate the UCS by utilising data from triaxial tests. It is hoped that with the level of accuracy demonstrated in this publication, the calculation of UCS from triaxial tests becomes more common, and it becomes one of the standard outputs from triaxial tests. **Author Contributions:** Conceptualization, methodology, analysis, and writing [PERSON]; Performing the laboratory test, [PERSON]; Quality control, reviewing, and discussion, [PERSON]. All authors have read and agreed to the published version of the manuscript. **Funding:** This paper is a part of the research project NoRSTRESS, an Innovation Project for the Industrial Sector (IPN), funded by the Norwegian Research Council (Grant/Project number: 320654), in cooperation with SINTEF, NTNU, Hafslund E-CO Energi AS, Hydro Energi AS, Sira-Kvina kraftskap DA, Skagerak Kraft AS, and Stakraft AS. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The datasets generated and/or analysed during the current study are not publicly available due to the policy of our laboratory but are available from the corresponding author on reasonable request.