Abstract: Duncan-Chang constitutive model is commonly used in the numerical analysis of the geotechnical problems related to coarse-grained soils. To explore the applicability of this model under complex stress path conditions including axial loading, unloading and lateral loading, a series of triaxial tests is conducted on coarse-grained soils to determine their mechanical properties and constitutive parameters. Based on the principle of similarity, the centrifugal models of a rockfill dam are prepared, and the centrifuge model test of a rockfill dam under complex stress path conditions is performed using the coars-grained soil with the same gradation and particle size in triaxial tests. The tests are conducted by changing the centrifugal acceleration to simulate loading and unloading conditions, and using the upstream impoundment to simulate the lateral loading. A three-dimensional numerical analysis of the centrifuge model test is performed using software ABAQUS. The effects of the sidewall friction and the initial stress conditions are studied. It is shown that the initial elastic modulus of soil can significantly influence the calculated results and the initial stress should assume the stress under the action of gravity in numerical simulations. Duncan-Chang constitutive model can better describe the behavious of the coarse-grained soil under the loading stress path than under the unloading stage; and thus the unloading modulus need to be determined with a proper method.

Key words: coarse-grained soil, Duncan-Chang constitutive model, centrifuge model test, numerical simulation