Investigating The Engineering Propertis Of Soils Found In Shewa Robit Town

Abstract

Geotechnical investigations are made to determine those geologic, seismologic, and soils conditions that affect the safety, cost effectiveness, design, and execution of a proposed engineering project. The objective of this thesis is to investigate the engineering properties of soil found in Shewa Robit town. The methodology used for this thesis was basically includes visual identification, sampling, laboratory tests, and analysis of results. Samples are collected both from 1.5m and 3m in order to determine the results of index properties, particle size distribution, compaction characteristics, consolidation, free swell, and shear strength parameters. And appropriate laboratory tests was performed according to AASHTO and ASTM standards. But since the study area soil is found to be in tropical region, modified classification methods must be used additionally. At two test pits the depth of 3m for taking soil samples is not reached because of the reason that a fractured rock is encountered, for the study area the variation of NMC is due to the difference in vegetation cover of the ground surface. Specific gravity of soil for the study area is found to be in similar range of Gs values for silt and clay soils. According to AASHTO classification, the study area soil is clay, it is fair to poor range to be used as a subgrade material for highways. According to USCS the soil in the study area is found to be CH and MH. Relatively higher values of LL, PL, and PI shows that the soil is cohesive by its nature. UCS test results shows that the study area soil undrained shear strength and undrained cohesion values are the values expected for fine grain soils. Compaction test result shows that the OMC value is the value expected for cohesive soils of high plasticity. MDD values also shows that for fine grain soils a less value of density is expected. Since OCR for the soil is greater than one, the soil is over consolidated. This shows that the current overburden pressure is not maximum load that the soil experienced. Since the k value of the soil is less, the soil is almost impermeable. The Atterberg limit value of the study area shows that the soil is fine grain soil which includes both silt and clay.