Assessment of particle breakage in rockfill materials using triaxial testing

All rockfill materials subjected to stresses above the normal geotechnical ranges exhibit considerable particle breakage. Particle breakage and crushing of the large particles to smaller ones result in a lower strength and higher deformability. The breakage of particle that is observed in the large scale triaxial tests، is usually expressed quantitatively by the Marsal breakage index،. This paper presents a method for calculating at any axial strain level in the large triaxial tests. The model used Rowe’s minimum energy principle ratio. The key parameter in modeling، is the friction angle which excludes dilation and breakage effects،. The results indicate that the internal friction angles at confining pressure equal and less than 200 kPa at the constant volume state is a unique value. Moreover، there is a linear relationship between the variation of energy spent on particle breakage to Marsal Breakage index with confining pressure، at failure axial strain.