Evaluating the geomechanical properties of Misis fault breccia (Turkey)

This study investigated the correlations between the uniaxial compressive strength (UCS), elastic modulus (E) or the differential stress (Δσ) and density, P- and S-wave velocity, volumetric block proportion (VBP  ), average block diameter (D¯block), average block diameter factor (ABDF), aspect ratio and roundness. The results were evaluated by both simple and multiple regression analysis. Simple regression analysis results show no correlation between UCS, E or Δσ and the other examined parameters, except S-wave velocity. A correlation was, however, found between UCS and S-wave velocity for 25% and 75% VBP. Other significant models including density, P- and S-wave velocity and textural properties for the prediction of UCS and Δσ were found by multiple regression analysis. From these results it is concluded that the strength of the Misis fault breccia cannot be defined by a single parameter such as VBP as is the case for some bimrocks. It is also concluded that the models developed by multiple regression analysis can be used to predict the UCS and Δσ of the Misis fault breccia. The multiple regression models including two or three independent variables are the most practical equations. Using these equations to predict the UCS and Δσ of the fault breccia is easier, faster and cheaper than conducting triaxial or uniaxial compressive strength tests.