Seged, Hadush (PhD)uba, Bantayehu2018-06-202023-11-112018-06-202023-11-112011-06http://etd.aau.edu.et/handle/12345678/2138InEthiopia,somanyresearchesweredoneoncharacterizingexpansivesoilsofseveraltownsbutonlyasinglestudy,doneonAddisAbabaexpansivesoil,existsontheunsaturatedshearstrengthbehaviorofexpansivesoils.ThepresentstudyaddressesexaminingtheexpansivesoilsinArbaMinch–atownwithagreatportionofitsterraincoveredbythesamesoilbutnotconsideredinpreviousstudies.Alaboratory-testingprogramwasplannedandcarriedoutonundisturbedsoilsamplestakenfrom10differentlocationsinthetownforswellingpressuretesting;andamongthese,onepitwasallottedforunsaturatedshearstrengthstudy. Thelaboratorytestresultsrevealedthattheswellingpressurerangesfrom74.53to571.29kPa,SpecificGravityfrom2.63to2.80,PlasticityIndexfrom49to77%,ShrinkageIndexfrom81to117%andFreeSwellfrom94.0to165.0%.Themeasuredswellingpressuresandthegeotechnicalparametersdeterminedfromidentificationtestsareusedtoassessthevalidityofalreadydevelopedexpressionsbyvariousresearcherstothesiteunderstudyandnewmodels,thatrelateswellingpressurewithindexandphysicalproperties,aredevelopedusingSPSS16.0forwindowssoftware. Theresultsfromunsaturatedshearstrengthtestsperformedwitha50kNmodifieddoublewalltriaxialmachineonanundisturbedsamplesettingmatricsuctiontobe100kPa,150kPaand200kPaforaneffectiveconsolidationpressureof200kPahaveclearlyindicatedthesaturatedcasetoyieldsmallershearstrengththantheunsaturatedone.Themaximumdeviatorstressshowedtoincreasefrom107.61kPato174.35kPawithanincreaseinmatricsuctionbuttheshapeofthestress-straindiagramremainedidentical.enCivilEngineeringCivilEngineeringThesis