Settlement and Particle Breakage of Soft Rockfill Materials in Medium Scale Oedometer

Rockfill materials are used in construction projects such as dam construction, road construction and so on. Due to the increasing use of these materials, experiments and studies have also been carried out on this material and usually, these studies have been carried out on strong rockfill materials. Today, the use of soft and weak rockfill materials has expanded because the economic and environmental issues. These marginal materials traditionally would not be used owing to their unfavorable engineering properties that is, low strength, high compressibility, and proneness to material degradation with time. Therefore, the use of soft rocks excavated on site as rockfill materials for high rockfill dams is still a controversial issue, as weathering takes place when the rock is exposed to an environment in which variations in air, temperature, and water content are involved. and still no comprehensive studies have been conducted on soft rockfill materials and need more information on the behavior of these materials in different conditions. One of the most important subject discussed in the rockfill materials is the particle breakage phenomena. Particle breakage index that quantifies the degree of particle breakage, can reflect the degree of particle crushing of material. To select weak rockfill materials, we visited the Nohob dam that is under construction and rockfill material in spillway excavation section is thrown away and it is not used in the construction of the dam. With considering that the dimensions of the usable rockfill material may be much larger than the dimensions of the laboratory equipment. Therefore, it is always a matter of scaling and matching the results of the laboratory and the field from the important items of rockfill materials. In this research, the behavior of weak rockfill materials has been studied in medium scale oedometer apparatus, in dry, wet and saturate conditions and also Los Angeles experiment is done. Based on the present study, the particle breakage increases with the addition of water and in saturate conditions, particle breakage also has a slight increase compared to wet conditions and for settlements and deformations of wet and dry specimens of materials show that wet specimens settlements are more than dry specimens.