Geotechnical Properties Evaluation of Selected Reservoir Sediments in Samarra Barrage and Wind Dam, Iraq

Abstract

This study was conducted on selected sediments from the Iraqi dam reservoir to verify their quality, the geotechnical properties including physical, engineering, chemical, and mineralogical characteristics. It was found that the study area soil is similar to the soil in the Mesopotamian plain areas where silts have low plasticity in the Samarra barrage and have medium plasticity at the Wind dam. moisture content is low in the Samarra barrage because sampling is done in the summer season, and high in wind dam due to the rain and snow in the winter. While the specific gravity values converge, because the fine sediment have originated from different sources. The mechanical properties, direct shear test show that the values of cohesion and angle of internal frication is with the natural range of known values of silt soils, while the consolidation test for sites shows that the normal values, Pre consolidation pressure, compression index ، swelling index over consolidation ratio are greater than 1, which indicate over consolidation soils. The total dissolved solids for sites are less exceeded 0.5%, the gypsum content is higher than 0.5%. the organic matter content is less than 0.5%. pH value shows that the sediments are alkaline. The mineralogical test of the sediment using XRD shows that the mineral contents of the analyzed sediment are composed mainly of the quartz, calcite, dolomite, gypsum, albite, and clay minerals such as montmorillonite, chlorite, illite, and kaolinite.