Ultimate Bearing Strength on Rectangular Footing Resting Over Geogrid Reinforced Sand Under Eccentric Load

1. International Journal of Trend in International Open Access Journal International Open Access Journal | www.ijtsrd.com International Journal of Trend in Scientific Research and Development (IJTSRD) Research and Development (IJTSRD) www.ijtsrd.com ISSN No: 2456 - 6470 6470 | Volume - 3 | Issue – 1 | Nov – Dec 2018 Dec 2018 Ultimate Bearing Strength Over Geogrid Reinforced Sand Under Eccentric Load Over Geogrid Reinforced Sand Under Eccentric Load Over Geogrid Reinforced Sand Under Eccentric Load Ultimate Bearing Strength on Rectangular Footing Resting Rectangular Footing Resting Singh Avtar1, Anu2, Pershotam Singh3 Singh Avtar 1 1PG Student, 2Assistant Professor (Geo-tech) G.G.G.I Dinarpur (Ambala), Haryana Civil Engineer, PWD Jammu and Kashmir calculateusingtheoryof elementmethod,and performinglaboratorytest surveyofthe subjectshowsthat ultimatebearingcapacitytheories verticalloadoftherectangular otherhandiftheloadis distributionbelowthefooting causingunequalsettlement willresultinthetiltoffooting. withrise eccentricitytowidth ofeccentricitytowidth(e/B) edgeofthefootingaway contactwiththesoil which reductionof theeffectivewidth reduction oftrue bearingstrength Researchersareintroducingreinforcing metalstrip,geophone,geotextile enhancethetrue bearing strength EQUIMENTSANDMATERIALS Thebasicpurposeofthisresearch bearingcapacityofreinforced Biaxialgeogridisusedtoreinforce tankofdimension1X 0.504 prepareforsandbed. MATERIAL SAND 1.SampleCollection: It is sand workiscollectedfromnear by River).Thatsandiswash fromofsoil,grassroots, materialsandthenthewash oven. 2.CharacteristicsofSand: All the areconductedatsamerelative 1,2Department of CE, (Geo , Haryana, India 3Civil Engineer, PWD Jammu and Kashmir ABSTRACT There is number of works has been carried out for the evaluation of an ultimate bearing strength of shallow foundation, supported over geogrid reinforced sand and subjected to load on center. Some experimental has been study for calculation of the bearing strength of shallow foundation on geogrid reinforced sand under eccentric loading. However that the studies for strip footings. The main purpose of the research work is to conduct model tests under the laboratory with utilizing rectangular surface foundation rest over the reinforced sand. The true bearing capacity of eccentrically loaded rectangular footing resting over geogrid reinforced sand can be determined by knowing the ultimate bearing strength of rectangular footing resting over reinforced sand bed and subjected to central vertical load with using reduction factor (R kR). An equation for reduction factor for rectangular footing resting over geogrid reinforced sand is developed on based of the laboratory model test results KEY WORDS: Ultimate Bearing Strength, Load, Reinforced Sand Bed. INTRODUCTION Foundationisthelowerpartofany veryimportantpartofany structure onshoreoroffshorestructure.That receivevery bigamountofloadfrom andtransmittedtheloadonthefoundation. thefoundationshouldbestrong sustaintheloadof superstructure. thestructureisusuallydependsonthe foundation.Since it isveryimportantpart, bedesignedwell. Themainproblem bearing capacityissolvedwithhelp analyticalexperimentalwork.Thefirst ofplasticityorfinite secondisreachedby model,theliterature thatthemajorityofthe theoriesinvolve centric rectangularfooting. Onthe iseccentric,thestress footingwillbenouniform at twoedgeswhich footing.Thetitlewillrise widthratio(e/B).Theratio isgreater than1/6,the fromloadisloseits whichwillresult onthe widthoffootingandhence strengthoffoundation. reinforcing materiallike geotextileandgeogridto strength onfoundation. There is number of works has been carried out for the evaluation of an ultimate bearing strength of shallow the reinforced sand and subjected to load on center. Some experimental has been study for calculation of the bearing strength of shallow foundation on geogrid reinforced sand under eccentric loading. However that the studies for se of the research work is to conduct model tests under the laboratory with utilizing rectangular surface foundation rest over the reinforced sand. The true bearing capacity of eccentrically loaded rectangular footing resting over an be determined by knowing the ultimate bearing strength of rectangular footing resting over reinforced sand bed and subjected to central vertical load with using reduction factor (R kR). An equation for reduction factor for rectangular er geogrid reinforced sand is developed on based of the laboratory model test MATERIALS researchistodiscoverthe reinforced sandbed. Tenser reinforcethesand. Test 0.504X0.655misusedto Ultimate Bearing Strength, Eccentric structure,but whether it is Thatpartwhich superstructure foundation. Therefore enoughto Theworkof theworkofthe part,so it should problemofTrue helpofboth firstone canbe sandusedfortheresearch near byjammu (Tavi washand it usefor free roots,and anotherorganic washspecimenisdriedin All thepracticallywork relativedensityof69%. @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 840

2. International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470 Theoverall averageunitweightof relativedensityis1.46g/ccandinternal angleisfindouttobe40.90by testoftherelativedensity. ofsandonthe internalfriction Table2.Propertiesof Parameters Polymer Tensilestrengthat2% strain Tensilestrengthat5% strain Aperturesize(W) Apertureshape Ribwidth(w) Junctionstrength ofthegeogrid Value bysheardirect PolypropylenePp strain 7KN/m strain 14KN/m 39*39mm Square 1.1mm 95% Table.1:GeotechnicalProperty Property Specific gravity (G) Effective particle size (D10) Mean particle size (D50) (D60) (D30) Coefficient of uniformity (Cu) Coefficient of curvature (Cc) Maximum unit weight Minimum unit weight Angle of internal friction (degree) 40.9 Maximum void ratio (emax) Minimum void ratio (emin) ofSand Value 2.64 0.33mm 0.455mm 0.47mm 0.42mm 1.424 1.137 14.87 kN/m3 2.64 0.33mm 0.455mm 0.47mm 0.42mm 1.424 1.137 14.87 kN/m 13.42kN/m 13.42kN/m3 40.90 0.929 0.741 TESTTANK Thesizeofthetankismade codeandfromtheresultofsome 1962saidthatlowestsizeshell thewideof testplatetodevelop zonewithoutanyinterference tanksize,thereissomescale influencetheultimatebearing restingovergeogrid reinforced (RKR)is reductionfactorisdefined madeuponthebaseofIS some literature.IS1888- shellbeatleast 5 times developthefullfailure interferencetoside. Duetothe scaleeffect whichwill bearingstrengthoffooting reinforcedbedsand. factor definedas: 0.929 0.741 ??? (? ?) ??) ) GEOGRID Theshapofgeogridsistheseparate geosynthetics designed Geogridsisthecategorizedbyarelatively strengthanda samedistributedgroup openingsinbetweenlongitudinalandtransverse Theopeningsareknownaperture.That allowsandparticleonboth sideof geogridtocomeonthedirectcontactwhich interaction betweenthegeogridand baseofstrength direction,geogridsis UniaxialandBiaxialwhileclassifiedlike Flexiblebasisonrigidity. Inpresentstudyg isusedtomodeltestisbiaxialflexiblegeogrid physicalcharacteristicsisshowninTable (1- ???(?? WherequR(e)andquR(e=0) bearingstrengthofreinforced eccentricandcentricloading EQUIPMENTUSED STATICLOADINGUNIT Ahydraulicallyoperatedstatic usedtoapplytheloadover test. Theshaftissupported whichsupplythe reaction applicationofload. PROVINGRING Provingringof20kN,25kN, useduringpracticallywork appliedloadoverthefoundation practicallyt work. Thetop connectedwiththemovable uniton theotherhandthe withthemetallicballwhich footing DIALGAUGE Twonumberofdialgaugewhich settlementupto50mmwith isusedduringthepractically separatetypeof uR(e=0)aretheultimate reinforcedbedsand under respectively. reinforcement. reinforcement. for relativelyhightensile groupofbig transverse rib. Thatopenings ofthemounted whichrisethe sand.. Onthe classifiedlike likeRigid and studyggeogrid geogridwhose Table3.2. staticloadingunitis overthe foundationduring supportedwithhorizontalbeam reactionontheshaftduring 25kN,50kN&100kNare to measuretheactual foundationduringthe topofprovingringis shaftofstaticloading bottomisinconnected whichisresting overthe whichiseasttomeasure leastcountof0.01mm practicallywork.Needleofthe Figure1FlexibleGeogrid Geogrid @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 841

3. International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470 dial gaugeisplacedoverthetwo adjacentcornerofthefooting. Magnetic whichissupportedwithtesttankisused thedialgauge. MODELFOOTING ThethicknessofModeltestfooting3cm ofmildsteelareusedfor experimental 1cmdeepcirculargroveismadetohold ballon onefaceofthefootingatcenter eccentricityof0.05B,0.1B&0.15B from ofthealonefootings.Sandisusewhile footingwith thehelpedofepoxyglue rough therefore that foundationandfoot ofsoilcandeveloped applicationofload MODELTESTANDMETHODOLOGY Tostudythebearingstrengthofeccentrically foundation,laboratorymodel testare overrectangularfootingrestingon reinforcedwith numbersoflayersgeogrid. Model testhasperformedoversandremolde density, footand aneccentricityvaried 0.15Bandnumberof reinforcement 2, 3 &4 PLACEMENTOFGEOGRID On the caseofreinforcedsandbed, it todecidethemagnitudeofu/B andb/B morebenefitin the bearingstrength sand.After then throughmanyliterature, beenfoundthat(u/B)crforstripfoundations between0.25and0.5,(b/B)cris8and footingandsquarefoot respectivelyand between0.25to0.4. diagonallyat Magneticbasis usedtosupport 3cmmadeup experimentalwork.A holdthemetallic centerandan fromthecentre whilethesideof gluetomake it in developedon Figure4.2Placementof ofgeogridduring experiment. experiment. friction between RESULTSANDANALYSIS Loadtestshavebeencompletely rectangularofsizefootings 9cmx28cmrestingoverunreinforced reinforced sandbedwitheccentricity 0.0to0.15B.Thetruebearing isdetermined fromloadsettlement tangentintersectionmethod. BEARINGSTRENGTHOF SAND MODELTESTRESULT Resultsofloadtesthavebeen settlementcurveasshownin footingsize10x18cm(B/L=0.55) (B/L=0.32 respectively. observedthattruebearing eccentricitywidthratio(e/B thetotalsettlementatfailure eccentricitywidthratio(e/B) thegraph showninFigure5.1 beconcludedthattheRatioof decreases,loadcarryingcapacity ANALYSIS completelyonmodel footings like10cmx18cmand unreinforcedaswellas eccentricityvaryingfrom bearingcapacityforeachtest settlementcurveusing METHODOLOGY eccentricallyloaded areperformed on bed sand geogrid. Model remoldeonone variedfrom0to reinforcementvariedas0, OFUNREINFORCED beendrawintermofload in Figure5.1and5.2for (B/L=0.55)and9x28cm graph, bearingcapacitylesslike )andalsoincreasesin failure loaddecreasesas (e/B)increases.Bycompare 5.1and5.2, it canalso ofwidthto length(B/L) capacityoffootingincreases isan essential b/Btotakethe ofreinforced literature, it has foundations vary and4.5forstrip and(h/B)crlies From From it is Figure 4.1 Cross-section showing sand bed and multiple number of reinforcement section showing sand bed and reinforcement Figure4. Load-settlement curve of unreinforced sand bed (B/L=0.55) unreinforced sand bed (B/L=0.55) settlement curve of bed @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 842

4. International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470 Figure5 Load-settlement curve of unreinforced sand bed (B/L=0.32) settlement curve of unreinforced Figure 8 Load-settlement curve for B/L=0.55 & N=4 and different e/B N=4 and different e/B ratio settlement curve for B/L=0.55 & BEARING REINFORCEDSAND MODELTESTRESULT The Laboratorymodeltestshavebeen with usingrectangularfootwith B/L=0.55 restingoverthegeogridreinforcedsand. reinforced byplacemultilayer(N=2,3, withdf/Bratioequalsto0.6,0.85&1.1, thedepthoflowermostgeogridlayerfrom footingand Bisthewidthoffooting. appliedcentrallyaswellaseccentrically modelfootuse staticloadingmachine. Settlementcorrespondingto each load havebeenwritedownandloadsettlement havebeenplotted. SUMMARIZEDRESULTS FUTURE WORK There is a numberoflaboratory conductedtofindtheultimate ofrectangularmodelfootings reinforced sandandsubjected eccentricload.Allthetestshas footingrestingover thesurface. Following is thesummarized researchwork. An ultimate foundationforun-reinforced soildecreaseswiththeincrease ratioi.e.e/B. An ultimatebearingstrength increaseswiththeincrease reinforcementlayer. Reductionfactorforthefooting 0.32 has been combinedtogetasimple reductionfactorforrectangular Equation5.11. SCOPEOFFUTUREWORK On the present study theresearch ultimate bearingstrengthof rectangularfootingwithB/L= reinforcedsandbed.During time aspectssimilartoshallowfoundations studied. Thework for should mentionedpoints: REFERENCES 1.Terzaghi,K.(1943).Theoretical Wiley,NewYork.Meyerhof InvestigationfortheFoundations Dense Sand.” STRENGTH OF GEOGRID RESULTSANDSCOPEOF laboratorymodeltestshasbeen ultimate loadbearingcapacity footingsrestingongeogrid subjectedtovertical an hasbeenconductedfor surface. beenpreform B/L=0.55&0.32 sand.Thissandis 3,4)geogrids 1.1,wheredfis frombottomof footing.Thae loadis eccentricallyon the machine. The loadincrement settlementcurve summarizedresultsofpresent strength bearing reinforcedand reinforced increaseineccentricity of the strength ofthefoundation increasein numberof footingwithB/L=0.55& alonely generalequationto rectangularfootingasshownin and then derived Figure6. Load-settlement curve for B/L=0.55 & N=2 and different e/B ratio N=2 and different e/B ratio settlement curve for B/L=0.55 & WORK researchworkisrelatedto ofeccentricallyloaded =0.55&0.32restingon timeconstraint, another foundationscannotbe shouldconsiderthebelow TheoreticalSoilMechanics, York.MeyerhofG.G.(1953).“An FoundationsofaBridgeon Figure7. Load-settlement curve for B/L=0.55 & N=3 and different e/B ratio settlement curve for B/L=0.55 & Proceedings Proceedings of the ratio @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 843

5. International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470 foundationwidthonmodel capacity reinforcement.” Engineering12,pp133-141 modeltests for thebearing with and Gelogical 3rdInternational Mechanicsand FoundationEngineering, 66-70 Conference on Soil of sand sand geogrid Engineering,2,pp. Geotechnical Geotechnical 141 2.Meyerhof research foundationCanadian Geotech. J. 1(1), pp 16 G. on G. the (1963). bearing “Some Some capacity 1(1), pp 16 recent 9.YetimogluT.,Jonathan A.(1994).“Bearingcapacity footings on Journal of 120,12. T.H.W.,Saglamer capacityof rectangular of geogrid geogrid-reinfoced Geotechnical Engineering,ASCE, sand.” 3.Prakash, S., Saran, S. (1971). “Bearing capacity of eccentrically loaded footings.Journal MechanicsandFoundation,ASCE, 118. Prakash, S., Saran, S. (1971). “Bearing capacity of Geotechnical JournalofSoil 97(1),pp.95- 10.Zhao,A.(1996).“Failure ReinforcedSoilStructure. Geomembranes14,pp289 FailureLoadonGeosynthetic Structure.”Geotextile 289-300 and 4.Vesic,A.S.(1973).“Analysisofultimate ofshallowfoundations.”J.ofSoil Found.Div.,ASCE,99(1),pp.45-73. ultimateloads Soil Mech.and 73. 11.Huang,C.C.,andMenq, FootingandWide-Slab sandy ground.” and Geoenviornmental 123(1),pp.30-36. Menq,F.Y.(1997).“Deep- effectsin reinforced of Engineering,ASCE, 5.Purkayastha, “Sensitivityanalysisforeccentrically footings.”J.Geotech.Eng.Div.,ASCE, R.D., Char, R.A.N. R.A.N. eccentricallyloaded ASCE,103(6),647 (1977). Journal Journal Geotechnical 6.Highter “DimensioningFootingSubjected Load.”JournalofGeotechnicalEngineering 111,No.5 W. H., Anders SubjectedtoEccentric EngineeringVol J. C. (1985). 12.Dash, Rajagopal,K.(2001). strip footings reinforced Geomembranes,19,pp.235 S. K., Krishnaswamy, Krishnaswamy, “Bearingcapacityof supported on Geotextiles 235-256 N. R., supported sand.” geocell- and 7.Khing,K.H.,Das,B.M.,Puri,V.K., Yen,S.C.(1993).“Thebearing strip foundation sand.” Geotextile pp351-361 K.,Cook,E.E., geogrid Geomembrane capacityof Geomembrane12, 13.Shin,E.C.,Das,B. Ataler,C.,(2002).“Bearin fondation GeotechnicalandGeological pp169-180. M.,Lee,E.S.,and Bearincapacityof strip on and geogrid reinforced on geogrid geogrid-reinfoced Geological Engineering20: sand.” 8.Das,B.M.,Omar,M.T.(1994).“ “Theeffectof @ IJTSRD | Available Online @ www.ijtsrd.com www.ijtsrd.com | Volume – 3 | Issue – 1 | Nov-Dec 2018 Dec 2018 Page: 844