Elastic modulus of intact rocks (E) is one of the most important parameters in the initial and final design of rock engineering projects. Laboratory measurements of E require the high quality core samples and expensive tools which cause it is very costly and time-consuming. As an alternative, indirect models i.e., Mamdani fuzzy inference system (MFIS) and multiple regression analysis (MRA) are uses to determine E in this research. The proposed models are constructed based on the measured data in Azad and Bakhtiary dam sites. To estimate E, easily determinable variables including depth of coring, density, porosity and durability index are considered as the input parameters. Models evaluation shows that MFIS performance is considerably better than the MRA model and its results are quite consistent with measured data. Finally, sensitivity analysis reveals that density and depth of coring are the most and least effective parameters on elastic modulus in this study.
