Effect Of Sample Height On Stress-Strain Behavior And Undrained Shear Strength Of Saturated Red Clay Soil In Buno Bedelle Using Uu-Tri-Axial Test: In Case Of Gechi-Yanfa Road Project.

Abstract

The Qualities Of Soil Are Highly Heterogeneous And Unpredictable Natural Materials That Fluctuate With Environment, Loads, And Drainage Conditions. Clay Is A Fine-Grained Soil That Is Well-Known As A Very Complex Natural Formation. Red Clay Soil Is A Type Of Clay Soil Commonly Available In Rainy Areas Of Western And South-Western Regions Of Ethiopia Like Buno Bedelle Zone As Mentioned By ERA Design Manual, (2013). Therefore, It Is Very Vital To Study Engineering Properties Of Red Clay Soil In Its Saturated Form Because Their Characteristics Rely Not Only On The Sort Of Object But Also On The Circumstances In Which It Occurs. To Use This Type Of Soil For Construction Purposes, The Detail Knowledge Of Its Engineering Properties Is Very Important. This Research Aims At Investigating The Characteristics Of The Soil Found In And Around Gechi Yanfa. To Conduct This Study Soil Samples From A Test Pit Were Collected To Be Classified As The Red Clay Soil Based On Its Basic Behaviors Like Plasticity, Low Compressibility, Gradation, Permeability And Xrd Mineralogical Analysis, Stress-Strain Behavior, And Undrained Shear Strength Of The Saturated Clay Soil At Specified Sample Height (H/D) Ratios. This Research Presents The Results Of Some Index And Engineering Properties Including Atterberg Limits, Compaction, Free Swelling And Finally The Effect Of Sample Size (H/D) Ratios (1.5,2 & 2.5) On Stress-Strain Behavior And Undrained Shear Strength Of Disturbed Srcs. The Result Reveals That The H/D Ratio Of Fully Saturated Red Clay Soil Of 1.5,2 & 2.5 Under Chamber Pressure (??3) Of 60 Kpa Is Su=43.77 Kpa At??A=2.67%, Su=42.46 Kpa At??A=2.65% And Su=40.77 At??A=2.40% Resp. And Su=43.76 Kpa At??A=2.77%, Su=42.43 KPA At??A=2.70% And Su=40.76 At??A=2.56% Under Cell Pressure 100 Kpa Whereas The Increase In Cell Pressure From 60 To 100 Kpa Did Not Affect Su, ??A &??U For The Saturated Red Clay Soil. Except For Angle Of Internal Friction (??U=0) In All Cases, The Values Of Undrained Shear Strength (Su) And Axial Strain (??A) Were Affected By The Change Of Sample Size (H/D) Ratios And Also The Stress-Strain Curve Changed From Ductile To Brittle Failure As H/D Ratios Of The Soil Sample Increases. The Result Shows That The Value Is Reliable Because The Su Value Is Obtained From Total Stress, Which Is Overestimated And Hence H/D=2.5 Gave Us The Smallest Values Of Su & ??A Become Preferable To Testing Sample Size For The Saturated Red Clay Soil.