Abstract:
Investigation of the ground conditions is used for the economical design of the sub-structural elements. It is also necessary to obtained sufficient information on type, characteristics and distributions of a soil and rock underlying at a site of proposed structures for feasibility and economic studies for the proposed project
According to the results of this research that the natural water content ranged from 29%–34.58%, also in situ density from 1.39 g/cc–1.53 g/ccand specific gravity ranges from 2.60to 2.73.The liquid limit value of the soil on the study area ranged from 39 % to 60 % and the plastic limit value from 32 % to 46 % and plastic index from 2 %to 21 %.
Plasticity chart of the study area according to Unified Soil Classification System showed that soil falls below the A-line which was inorganic silt of medium to high plasticity (ML and MH respectively).Classifications of soils in the study area based on AASHTO Classification system was classified in group A-7-5, which weresilty clay soils with group index ranging from 4 to18. The group index results indicatd that generally the soils of the study area are poor for highway subgrade material. From the compaction test the maximum dry density (MDD) of ranged from 1.48g/cc –1.64g/cc andtheoptimummoisturecontent from 19.5 %to 32%. The shear strength parameters of the study area vary from place to place. The cohesion strength of the soil ranged from 24 to 55 kpa and the angle of internal friction from 24 to 450. The undrained shear strength of the soil obtained from the unconfined compression strength ranged from 46 to 92 kpa
