Abstract: The study was conducted on a coarse-grained soil from a certain dam, and true triaxial tests were performed under complex stress paths. The expressions of tangent volume ratio and tangent modulus in the Shen’s elastoplastic model are modified in three dimensions by introducing the corner function, and the modified Shen’s elastoplastic model is applied to the deformation calculation of a high earth-rock dam. The results show that the proposed dilatancy equation has a good fitting effect under different confining pressures and different intermediate principal stresses, and improves the problem that the original model overestimates dilatancy under high confining pressure. The modified tangent modulus better reflects the law that the tangent modulus of coarse-grained soil decreases gradually with the increase of stress ratio and the change characteristics that the tangent modulus finally approaches zero after reaching the peak stress ratio. The modified Shen’s elastoplastic model was applied to deformation calculations for a specific high earth-rockfill dam. By comparing the calculated results with the field measured data, it is found that the settlement deformation results of the core wall dam calculated by the modified model are close to the measured results, which can be used for the deformation calculation of the existing high earth-rock dam.

Key words: coarse-grained soil, elastoplastic model, true triaxial test, tangent modulus