Investigations on factors influencing the CBR value of some Aegean sands

The California Bearing Ratio (CBR) value of the soils is very important for geotechnical engineering and earth structures.A CBR value is also affected by the type of soil and different soil properties. With this in view, in this paper, an attempt has been made for investigating the factors that affect theCBR value of some Aegean sands collected from nine different locations in Manisa (Turkey). The sand samples were tested for mineralogy, particle shape and size, and specific gravity. In addition, the CBR tests were performed on these samples corresponding to different dry densities and the influence of dry density, relative density, water content, particle shape and size on theCBR value was examined. Multiple regression analysis (MRA) was performed to predict the CBR value of the sands by using the experimental results. It has been demonstrated that the MR equation proposed in this paperis efficient in determining the CBR value of Aegean sands and the computed values are in good agreement with those obtained from the experimental investigations. Moreover, several performance indices such ascoefficient of correlation, variance account for, mean absolute error, and root mean square error were calculated to check the prediction capacity of the MR equation proposed. The obtained indices make it clear that the equation, derived from the samples used in this study, apply well with an acceptable accuracy to be used for the CBR estimation at the preliminary stage of site investigations.