A Study of the Rockfill Material Behavior in Large-Scale Tests

Inspecting the behavior of the rockfill materials is of significant importance in analysis of rockfill dams. Since the dimensions of grains in such materials are greater than the conventional sizes suitable for soil mechanics tests, it is necessary to experimentally study them in specific large-scale apparatuses. In this research, the behavior of rockfill materials in two large rockfill dams constructed in northwest of Iran were studied using large-scale direct shear and triaxial tests. Various indices regarding the quantity of particle breakage in rockfill materials were assessed for both dams and an experimental correlation has been proposed between the Los Angeles Abrasion Value and internal friction angle of rockfill material. Also, the effect of surcharge intensity, grain size distribution and degree of compaction on the shear strength of rockfill material for both dams was studied. The findings indicate that increase in particle breakage leads to reduction of internal friction angle. Also, for a specific sample the particle breakage index increases with an increase in surcharge, percentage of gravel and degree of compaction.