2026 Volume 21 Issue 2 Pages 269-281
To identify physical properties highly correlated with the shear strength of coarse-grained soil, physical property tests and direct shear tests under constant pressures were performed on 30 types of coarse sand with different origins and production sites, and their respective correlations were examined. It was confirmed that the shear resistance angle Φ at failure, the residual shear resistance angle Φr are significantly influenced by the FU value, which represents the degree of surface roughness of soil particles, and the aspect ratio c/b, which is an indicator of three-dimensional particle shape. The degree of influence of each factor was evaluated. The deformation coefficient E, the slope IΦ of the logarithm of shear resistance angle versus normal stress, and the slope Id of the logarithm of dilatancy coefficient versus normal stress at failure are influenced by the FU value and the crushing stress of soil particles. As the density of the test specimen decreases, the influence of physical properties on the shear strength in direct shear test characteristics also diminishes. The obtained results represent that the FU value is most appropriate management index for shear strength characteristics of coarse-grained soils.
