Abstract：Based on the stress path of dam，the triaxial tests of coarse materials are carried out with constant ratios of the principal stresses and the stress increments to obtain the corresponding stress-strain relationship of course materials. According to the strength characteristics of coarse materials，a function is determined to describe the yield criterion of coarse materials. Based on this yield criterion and elasto-plastic theory，an elasto-plastic constitutive model for coarse materials is established. It can be expressed in invariants with clear concept，no odd dots and less parameters. In order to apply it to finite element method，the elasto-plastic matrix is deduced. It is shown that the stress-strain relations hip of coarse materials is in good agreement with experimental data.
