برآورد متغیرهای مقاومت برشی شیل های سازند شمشک با استفاده ازالگوریتم منطق فازی

Shear strength is one of the most important properties of mudrocks and shales in rock engineering and engineering geology. because of the ‎difficulty to obtain undisturbed samples of shales as required for determination of shear strength parameters, it is also the most difficult to ‎evaluate. this research investigated properties that can be used to predict the shear strength parameters of shemshak formation shales. thirty ‎samples of shales from various depths were collected from boreholes in shemshak formation in the site of siahbishe pumped storage ‎powerhouse. shear strength parameters (c and?), tensile strength (ts), quartz percent (qz %), porosity (n) and density (?) were determined ‎in lab for each sample. data were analyzed statistically and with fuzzy inference system to determine the relationships between shear ‎strength parameters with other properties. results show that cohesion and friction angle of shales can be meaningfully predicted from a few ‎engineering properties by fuzzy inference system. the adjusted r2 values between measured and predicted values for cohesion and friction ‎angle are 0.95 and 0.84 respectively. also the variation of regression coefficient (r2), performance indices (vaf) and root mean square error ‎‎(rmse) with were calculated as for the shear strength parameters, obtained from the multiple regression modeland the fuzzyinference ‎system, revealed that the prediction performance and accuracy of the fuzzy models are high and multiple regression equations not have ‎performance in prediction of shear strength parameters of shales.‎