Particles breakage phenomenon can strongly affect deformational behavior of the coarse granular materials, especially rockfiil materials. Large deformations can be recorded due to this phenomenon in high rockfill dams.
Common geotechnical constitutive models cannot simulate volumetric strains due to this phenomenon with a sufficient accuracy. In this research, a known hardening/ softening constitutive model on the basis of Mohr- Coloumb model, which is available in FLAC program, was used to predict the deformational behavior of the coarse granular materials. In this constitutive model, the strain hardening/softening feature can be simulated by the means of mobilized friction angle concept. Also, the potential function of it was defined on the basis of the mobilized dilatancy angle concept. Some modifications were applied to the potential function of this model to improve its ability to predict contractive volumetric strains due to particles breakage phenomenon.
The Masjed-e-soleyman dam is a high central clay core rockfill dam, located in the south-west of Iran. A series of large scale tri-axial tests was performed on the rock-fill materials of its shells. The results of the large scale tri-axial tests indicate that these materials have a high potential of crashing under shearing. The tri-axial tests were numerically simulated, and the parameters of the improved hardening/softening constitutive model were determined using back analyses. A three-dimensional finite difference numerical model of the Masjed-e-soleyman dam was developed during construction. Good agreement between numerical results and instrument data in the fields of deformation and stress confirms the accuracy and efficiency of the improved constitutive model to predict the deformational behavior of the rockfill shells due to crashing under shearing.