A fuzzy model to predict the uniaxial compressive strength and the modulus of elasticity of Shemshak Formation shales

The uniaxial compressive strength and modulus of deformability of intact rocks are highly important parameters for rock engineering and engineering geology projects. Because of the difficulty of measuring these parameters and the need for laboratory equipments for their prediction, indirect methods are often used. In this study, some predictive models using regression analysis and fuzzy inference system have been developed for the Shales cropping out in the Shemshak formation in Siahbishe area. For this purpose, a series of easy measurable parameters such as density, porosity and point load index were applied. Both multiple regression analyses and the fuzzy inference system exhibited good performance in prediction of the uniaxial compressive strength and modulus of deformability. The variation of regression coefficient (R2), performance indices (VAF) and root mean square error (RMSE) were calculated as for the uniaxial compressive strength and the modulus of deformability obtained from the multiple regression model and the fuzzy inference system revealed that the prediction performances and accuracy of the fuzzy model are higher than those of multiple regression equations in prediction of uniaxial compressive strength and modulus of deformability.