土方工程的地基勘察與施工-土木工程畢業(yè)設(shè)計外文翻譯

1、DESIGNEXECUTIONOFGROUNDINVESTIGATIONFEARTHWKSPAULQUIGLEYFGSIrishGeotechnicalServicesLtdABSTRACTThedesignexecutionofgroundinvestigationwksfearthwkprojectshasbecomeincreasinglyimptantastheavailabilityofsuitabledisposalarea

2、sbecomeslimitedcostsofimptingengineeringfillincrease.Anoutlineofgroundinvestigationmethodswhichcanaugment‘traditionalinvestigationmethods’particularlyfglacialtillboulderclaysoilsispresented.Theissueof‘geotechnicalcertifi

3、cation’israisedrecommendationsoutlinedonitsmeritsfincpationwithgroundinvestigationsearthwks.1.INTRODUCTIONTheinvestigationreuseevaluationofmanyIrishboulderclaysoilspresentsdifficultiesfboththegeotechnicalengineertheroadd

4、esignengineer.Theseglacialtillboulderclaysoilsaremainlyoflowplasticityhaveparticlesizesrangingfromclaytoboulders.Mostofourboulderclaysoilscontainvaryingproptionsofsgravelcobblesbouldersinaclaysiltmatrix.Theamountoffinesg

5、overnstheirbehaviourthesiltcontentmakesitveryweathersusceptible.Moisturecontentscanbehighlyvariablerangingfromaslowas7%fthehardgreyblackDublinboulderclayupto2025%flSouthWestNthWestlightgreyboulderclaydeposits.Theabilityo

6、fboulderclaysoilstotakeinfreewateriswellestablishedpoplanningofearthwksoftenamplifiesthis.Thefinesoilconstituentsaregenerallysensitivetosmallincreasesinmoisturecontentwhichoftenleadtolossinstrengthrenderthesoilsunsuitabl

7、efreuseasengineeringfill.Manyofourboulderclaysoils(especiallythosewithintermediatetypesiltsfinesmatrix)havebeenrejectedattheionstagebutgoodplanningshowsthattheycaninfactfulfilspecificationrequirementsintermsofcompactions

8、trength.Theionprocessshouldaimtomaximisetheuseoflocallyavailablesoilswithcarefulevaluationitispossibletouseincpate‘pomarginalsoils’withinfillareasembankments.Fillmaterialneedstobeplacedatamoisturecontentsuchthatitisneith

9、ertoowettobestabletrafficabletoodrytobeproperlycompacted.Highmoisturecontentlowstrengthboulderclaysoilscanbesuitablefuseasfillinlowheightembankments(i.e.2to2.5m)butnotsuitableftraffickingbyearthwkplantwithoutusingageotex

10、tileseparatgranularfillcappinglayer.Henceitisvitalthatthe3.SOILCLASSIFICATIONSoildeionclassificationshouldbeundertakeninaccdancewithBS5930(1999)testedinaccdancewithBS1377(1990).Theengineeringdeionofasoilisbasedonitsparti

11、clesizegradingsupplementedbyplasticityffinesoils.Fmanyofourglacialtillboulderclaysoils(i.e.‘mixedsoils’)difficultiesarisewithdeionsassessingengineeringperfmancetests.AsoutlinedpreviouslyIrishboulderclaysusuallycomprisehi

12、ghlyvariableproptionsofssgravelscobblesinasiltclaymatrix.Lowplasticitysoilswithfinescontentsofaround10to15%oftenpresentthemostdifficulties.BS5930(1999)nowrecognisesthesedifficultiesindescribing‘mixedsoils’–thefinesoilcon

13、stituentswhichgoverntheengineeringbehaviournowtakespriityoverparticlesize.Akeyparameter(whichisoftenunderestimated)inclassifyingunderstingthesesoilsispermeability(K).Inspectionoftheparticlesizegradingswillindicatemagnitu

14、deofpermeability.Wherepossibletriaxialcelltestsshouldbecarriedoutoneitherundisturbedsamples(U100’s)goodqualitycesamplestoevaluatethedrainageacteristicsofthesoilsaccurately.Lowplasticityboulderclaysoilsofintermediateperme

15、ability(i.e.Kofthederof105to107ms)canoftenbe‘conditioned’bydrainagemeasures.Thisusuallyentailstheinstallationofperimeterdrainssumpsatcutareasbrowpitssoastoreducethemoisturecontent.Hencewithsmallreductioninmoisturecontent

16、difficultglacialtillsoilscanbecomesuitableasengineeringfill.4.ENGINEERINGPERFMANCETESTINGOFSOILSLabatytestingisverymuchdictatedbytheproposedendusefthesoils.TheengineeringparameterssetoutinTable6.1pftheNRASRWincludeacombi

17、nationofthefollowing:?Moisturecontent?Particlesizegrading?PlasticLimit?CBR?Compaction(relatingtooptimumMC)?RemouldedundrainedshearstrengthAnumberofkeyfactsshouldbebneinmindwhenschedulinglabatytesting:?CompactionCBRMCVtes