Study On Some Static And Dynamic Properties Of Soils Commonly Found In Dire Dawa Town

Abstract

The Behavior Of Soils Under Static And/Or Dynamic Loadings Is Strongly Influenced By The Static And/Or Dynamic Properties Of Local Soil Deposits. Of Those Static And Dynamic Properties, The Shear Strength And The Shear Modulus And Damping Ratio Of Soils Are Critical To The Evaluation Of Geotechnical Engineering Problems. In This Thesis, It Was Aimed To Study The Shear Strength, Shear Modulus And Damping Ratio Of Soils Commonly Found In Dire Dawa, After Characterizing The Soil Using The Index Properties. Effects Of Strain Amplitude, Confining Pressure, Material Type And Loading Cycles On Shear Modulus And Damping Ratio Values Were Also Investigated. The Shear Strength Parameters (C And ??) Were Determined Using Strain-Controlled Direct Shear Test On Soil Specimens Remolded With Different Densities And Water Contents In Order To Simulate The Ground Condition. To Determine The Shear Modulus And Damping Ratio, Strain Controlled Cyclic Simple Shear Tests On Remolded Samples Were Performed. The Tests Were Carried Out As A Function Of Cyclic Shear Strain Amplitudes Of 0.01%, 0.1%, 1%, 2.5% And 5% Under The Axial Pressures Of 100kpa, 200kpa And 400kpa. According To The Results Of This Study, The Soils In Dire Dawa Town Are Low Plastic Silt And Poorly Graded Sand. The Values Of Shear Strength Parameters (C And ??) Of The Sand Range Between 1kpa To 9kpa And 260to 280 Respectively. And The Values Of Shear Strength Parameters (C And ??) Of The Silt Range Between 28kpa To 43kpa And 150 To 250 Respectively. The Cohesion Of The Soil Is Strongly Affected By The Water Content Of The Soil, While The Angle Of Internal Friction Of The Soil Is Not Significantly Affected. The Values Of Shear Modulus And Damping Ratio Of The Sand Range Between 1mpa To 38mpa And 3% To 24% Respectively. And The Values Of Shear Modulus And Damping Ratio Of The Silt Range Between 1mpa To 14mpa And 3% To 29% Respectively. The Shear Modulus Increases With Confining Pressure And Loading Cycles For A Given Shear Strain Amplitude, But The Damping Ratio Decreasing With Them. The Modulus Reduction And Damping Ratio Values Of The Silt Soil Are Close To The Corresponding Local Values, But The Modulus Reduction Values Of The Sand Are Lower Than The Corresponding Local Values, Especially At Lower Strains.