Efficiency of seismic wave velocity and electrical resistivity in estimation of limestone rock mass quality indices (Q , srm Q ) (Case study: Asmari formation, SW Iran)

In this work, the relationship between the P-wave velocity (V p ) and the Electrical Resistivity (ER) parameters with rock mass quality indices is investigated; parameters such as rock mass quality classification (Q ) and modified system for sedimentary rocks (Qsrm ). For making predictive models, about 1200 data-sets were extracted from sections drilled in Seymareh and Karun 2 Dam Sites (SDS and KDS) in Asmari Formation, SW Iran. The statistical and fuzzy methods were used to study the relationships between the geophysical parameters and the rock mass quality. Since in the Qsrm classification, the existence of cavities; and layering and rock texture are considered in addition to the parameters considered in the Q classification; it provides a better description of rock mass and is closely related to parameters p V and ER. The equations obtained for predicting Q and Qsrm showed the determination coefficients (R2) to be 0.48 and 0.67, respectively, and the coefficient of determination 0.86 for Qsrm was calculated by the fuzzy model. Finally, Mean Absolute Deviation (MAD), Variance Accounted For (VAF), and Root Mean Square Error (RMSE) were used to check the prediction performance of the statistical and fuzzy methods. The results of the calculated errors also showed that the fuzzy models were interesting because they had a good accuracy for predicting Qsrm . In addition, by increasing the degree of karstifiction, the efficiency of the geophysical method for estimation of Q decreased rapidly, which was due to ignoring the cavities in this category.