Estimation of Strength Properties of Shale from Some of Its Physical Properties Using Developed Mathematical Models

------------------------------------------------------Abstract---------------------------------------------------------Estimation of strength properties (uniaxial compressive and point load) from physical properties (density, porosity and rebound hardness) of shale rock type from Kogi State, Nigeria was investigated. The shale rock types were sampled and tested for their properties through in-situ and laboratory tests conducted. Schmidt hammer was used to carry out the in-situ testing of the rock on the field while rock samples were collected for laboratory test. Four samples of each rock type were prepared for the determination of density and porosity. The results obtained from the Schmidt hammer test and those of density determined from laboratory test were used to estimate the uniaxial compressive strength of the rock. The average density and porosity of the shale are 2.39 g/cm and 38.4%. The average uniaxial compressive strength and point load index values are 34.20 MPa and 1.60 MPa respectively. From the results, the strength parameters indicated high strength classification. The determined physical and strength parameters were analyzed statistically. Mathematical models were derived from the relationships between the parameters for the estimation of strength properties of the rock and the coefficient of their correlation (R) indicated strong relationship. The results obtained would be useful tools for the prediction of the strength properties of rocks having similar physical properties as the investigated rock type.