M Kianpour; M Sayari; A Uromeihy; M.R Nikudel
Abstract
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 ...
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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 ϕ), tensile strength (TS), quartz percent (Qz %), porosity (n) and density (ρ) 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.
M. Kianpour; M. Sayari; A. Oromiea
Abstract
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 ...
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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.