Jafar Mamizadeh; Zia Azizbeygi
Abstract
Backfill and backfill material supply in irrigation and drainage projects is very important in terms of technical feasibility and economics. In Eynekhosh-Fakeh pipelines project, with 230 km of GRP pipes, provision of the volume of soil for backfill around the tube is a challenge. GRP pipes are made ...
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Backfill and backfill material supply in irrigation and drainage projects is very important in terms of technical feasibility and economics. In Eynekhosh-Fakeh pipelines project, with 230 km of GRP pipes, provision of the volume of soil for backfill around the tube is a challenge. GRP pipes are made of fiberglass and are fragile and, therefore, selection of proper backfill, particularly for the lower layers, is very important. In this study, given the abundance of native sand material in the area, these materials were used around the pipes and compacted in separate experiments such as standard proctor compaction and flooding method. Results showed that materials with less than 12 percent fine grains of sand can be compacted up to 85 percent with flooding method, spending less time and achieving high work efficiency. In another part of this research, mixing of clay materials with sand, in order to provide the depth of the trenches for backfill, was studied. Analysis showed that adding sand materials to clay materials increased the density and reduced the percentage of various compounds such as gypsum, chlorine, and sulfate. Also, according to the soil plasticity index (PI) and density, quality of this mixture is suitable for backfill.