The Unsaturated Shear Strength and Swelling Charac Teristics of Expansive Soils of Arbaminch
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Date
2011-06
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Addis Ababa University
Abstract
InEthiopia,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.
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CivilEngineering, CivilEngineering