Investigation On Some Engineering Properties Of Soils Of Dera Town

Abstract

Dera Town Is Geographically Located In The Eastern Ethiopia And It Is The Transit On The Road From The Capital Town Of Addis Ababa And Adama To Assela. Due To Its Location, Investors Are Attracted To Construct In The Town. A Lot Of Civil Engineering Structures Are Under Construction; However, As Many Town Of Ethiopia, The Engineering Properties Of The Soil Underlying Town Are Not Well Known With Respect To The Intended Urban Development Plan. This Study Is, Therefore, Conducted With The Intention To Assess The Index Properties And Some Of The Engineering Characteristics Of Soil Of The Town. The Undisturbed Samples For Determination Of Natural Moisture Contents And Disturbed Samples For Free Swell Test, Grain Size Analysis, Atterberg Limit Test, Specific Gravity, Compaction, Sample Prepared From Compacted Sample For Direct Shear Test Using Standard Procter Test. The Grain Size Analysis Test Result Showed That The Dominant Proportion Of Soil Particle In The Study? Area Is Coarse-Grained Soils, Which Have Clay Content Ranging From 0.7-6%, Silt Faction 7.89-15.4%, Sand Fraction 62-86.10% And Gravel Fraction 1.8-27.20%. According To Atterberg Limit Test, The Liquid Limit Ranges From 14 To 20.3 %, Plastic Limit Ranges From 14.17 To 17.92% % And Plastic Index From Non-Plastic To 4.7%.The Specific Gravity Ranges From 2.60-2.68. Free Swell Value In Percent Ranges From 1-20%. The Moisture Content Of The Soils Ranges From 1426.92% And The Optimum Moisture Content (Omc) And Maximum Dry Density (Mdd) Varies From 18 To 26% And 1.4 To1.6 G/Cm3, Respectively. The Shear Strength Parameters, Cohesion (C) And Internal Friction Angle (??), Determined From Direct Shear Test Varies From 1.019 To 7.95 Kpa And 22.7?? To 29.7??, Respectively. The Samples Were Collected From The Site Had Been Conducted In Laboratory And Classified According To Uscs And Aashto. The Soil In The Study Was Silty Sand(Sm) And Poorly Graded Sand With Clay And Gravel Soil As Per Uscs And A-2-4 And A-3 As Per Aashto And The Soil Is Suitable For Road Way Pavement As Per Aashto Soil Classification System. Generally The Result Of This Study Indicates That The Soils Of The Study Area Possess Desirable Engineering Characteristics I.E. Low Compressibility, Good Shear Strength, Low Plasticity And Less Susceptible To Shrinkage And Swelling With Variation Of Moisture Content. The Outcome Of This Thesis May Be Applicable In Different Civil Engineering Sectors, Especially For Preliminary Investigations And Prefeasibility Study Of Civil Engineering Works Such As Foundation Work, Earth Dams, Earth Fills, And Other Works That Involve Soils