Peak Friction Angle of Soils as a Function of Grain Size

Numerous studies have attempted to correlate geotechnical properties and to produce semi-empirical methods for estimating geotechnical parameters when sufficient field or laboratory measurements are not available. In the case of Greek soil formations, several studies have been presented that relate in situ tests (standard penetration test, cross-hole, seismocone) and laboratory tests for cohesive soils. Statistical analysis of the data resulted in the formulation of empirical correlations between various soil parameters, often with reasonably high correlation coefficients. However, these relationships refer mainly to cohesive soils, because the majority of tests were carried out in such formations. In this paper, the correlation of the particle size and the peak friction angle for a wide range of Greek soil formations is investigated. A simple, but rational approach for estimating the friction angle is presented, which allows prediction of the shear strength of soil formations. Since this investigation covered a wide range of soils and the number of test results is significant, the obtained empirical correlations can be considered as reliable for Greek soils.