SR 710 Tunnel Evaluation Report.pdf

Tunnel Evaluation Report

Prepared for

September 5, 2014

Contents Section Page

TUNNEL REPORT_REV1.DOCXRO III

Introduction.........................................................................................................................................111.1 CurrentProjectAlternatives............................................................................................................11

1.1.1 LRTAlternative...................................................................................................................111.1.2 FreewayAlternative...........................................................................................................11

1.2 Scope...............................................................................................................................................121.3 PurposeandLimitations..................................................................................................................12

SummaryofTechnicalMemoranda......................................................................................................212.1 TM1:BoredTunnelGeometry........................................................................................................212.2 TM2:TunnelGroundCharacterization...........................................................................................212.3 TM3:TunnelExcavationMethods..................................................................................................222.4 TM4A:PreliminaryDesignConceptsfortheFreewayTunnelandCrossPassageLinings.............222.5 TM4B:PreliminaryDesignConceptsfortheLRTTunnelandCrossPassageLinings.....................232.6 TM4C:PreliminaryDesignConceptsfortheFreewayTunnelInternalStructure..........................232.7 TM5:EvaluationandControlofGroundMovements....................................................................242.8 TM6:PreliminaryDesignConceptsforFaultCrossings..................................................................242.9 TM7:PreliminaryDesignConceptsfortheFreewayPortalExcavationSupportSystems.............252.10 TM8:PreliminaryDesignConceptsfortheLRTStationandPortalExcavationSupportSystems.262.11 TM9:HandlingandDisposalofExcavatedMaterials.....................................................................26

References...........................................................................................................................................31

AppendicesA TM1 BoredTunnelGeometryB TM2 TunnelGroundCharacterizationC TM3 TunnelExcavationMethodsD TM4A PreliminaryDesignConceptsfortheFreewayTunnelandCrossPassageLiningsE TM4B PreliminaryDesignConceptsfortheLRTTunnelandCrossPassageLiningsF TM4C PreliminaryDesignConceptsfortheFreewayTunnelInternalStructureG TM5 EvaluationandControlofGroundMovementsH TM6 PreliminaryDesignConceptsforFaultCrossingsI TM7 PreliminaryDesignConceptsfortheFreewayPortalExcavationSupportSystemsJ TM8 PreliminaryDesignConceptsfortheLRTStationandPortalExcavationSupportSystemsK TM9 HandlingandDisposalofExcavatedMaterials

Figures

1 LRTAlternative2 FreewayTunnelAlternative

TUNNEL REPORT_REV1.DOCX 1-1

Introduction TheCaliforniaDepartmentofTransportation(Caltrans),incooperationwiththeLosAngelesCountyMetropolitanTransportationAuthority(Metro)isstudyingtransportationimprovementstoimprovemobilityandrelievecongestionintheareabetweenStateRoute2(SR2)andInterstates5,10,210and605(I5,I10,I210,andI605,respectively)ineast/northeastLosAngelesandthewesternSanGabrielValley.Atthetimeofthewritingofthisreport,theEnvironmentalImpactReport/EnvironmentalImpactStatement(EIR/EIS)isintheprocessbeingdrafted,andthisreportservesasareferencedocumenttotheenvironmentaldocumentationprocess.Thealternativesbeingconsideredatthisstageofthestudyarediscussedbelow.Thisreportfocusesonthetunnelsectionsassociatedwiththesealternatives.

1.1 Current Project Alternatives TheproposedalternativesselectedforevaluationintheEIR/EISphaseofthestudyincludetheNoBuildAlternative,theTransportationSystemManagement/TransportationDemandManagement(TSM/TDM)Alternative,theBusRapidTransit(BRT)Alternative,theLightRailTransit(LRT)Alternative,andtheFreewayTunnelAlternative.Previously,duringtheAlternativesAnalysisphase,otheralternativeswereconsidered;however,thesefivewereselectedforfurtherstudy(CH2MHill,2012).TheFreewayTunnelandLRTAlternativeswillincludetunnelsforsignificantdistancesovertheiralignments,andonlythesealternativeswillbediscussedfurtherinthisreport.Theotheralternativesdonotinvolvetunnelsectionsandarenotwithinthescopeofthisreport.ThealignmentsoftheLRTandFreewayTunnelAlternativesareshowninFigures1and2andaredescribedbelow.

1.1.1 LRT Alternative TheLRTAlternative(Figure1)wouldincludepassengerrailoperatedalongadedicatedguideway,similartootherMetrolightraillines.TheLRTalignmentisapproximately7.5mileslong,with3milesofaerialsegmentsand4.5milesofboredtunnelsegments.TheLRTAlternativewouldbeginatanaerialstationonMednikAvenueadjacenttotheexistingEastLosAngelesCivicCenterStationontheMetroGoldLineandcontinuesnorthtoendatanundergroundstationbeneathRaymondAvenueadjacenttotheexistingFillmoreStationontheMetroGoldLine.Twodirectionaltunnelsareproposedwithexcavatedtunneldiametersofapproximately20feeteach.SevenstationswouldbelocatedalongtheLRTalignment;ofthese,theAlhambraStation,theHuntingtonStation,theSouthPasadenaStation,andtheFillmoreStationwouldbeundergroundstations.Additionally,twooftheseundergroundstationexcavationswouldincludeadditionalspaceforacrossover(Huntington)andtailtracks(Fillmore).AdditionalinformationabouttheLRTAlternative,includingdiscussionsonaerialandatgradesegments,isincludedintheAdvancedConceptualEngineeringReport(CH2MHill,2014a).

1.1.2 Freeway Alternative ThealignmentfortheFreewayTunnelAlternative(Figure2)startsattheexistingsouthernstubofSR710inAlhambra,justnorthofI10,andconnectstotheexistingnorthernstubofSR710,southoftheI210/SR134interchangeinPasadena.TheFreewayTunnelAlternativehastwodesignvariations:atwinboretunnelandasingleboretunnel.Bothvariationsareapproximately6.3mileslong,with4.2milesofboredtunnel,0.7milesofcutandcovertunnel,and1.4milesofatgradesegments.Thetwinboretunnelvariationwouldconsistoftwosidebysidetunnels(onenorthbound,onesouthbound),andeachtunnelwouldhavetwolevelswithtwolanesoftrafficoneachlevel,foratotaloffourlanesineachtunnel.Eachboredtunnelwouldhaveanexcavateddiameterofapproximately60feet.Thesingleboretunneldesignvariationissimilarinlengthanddiameter;however,thesingleboretunnelvariationwouldconsistofonetunnelwithtwolevels.Thenorthboundtrafficwouldtraversetheupperlevel,andthesouthboundtrafficwouldtraversethelowerlevel.AdditionalinformationabouttheFreewayTunnelAlternative,includingdiscussionsonaerialandatgradesegments,isincludedintheProjectReport(CH2MHill,2014c).

1 INTRODUCTION


1.2 Scope ThisreportsummarizesthepreliminarydesignconceptsdevelopedfortheboredtunnelsandsomeassociatedundergroundcomponentsfortheFreewayTunnelandLRTAlternatives.Eleventechnicalmemoranda(TMs)havebeenpreparedtodescribethepreliminarydesignconceptsdevelopedforthisstageofthestudy.EachoftheseTMsisincludedasaseparateappendixtothisreport.ThefollowingTMswerepreparedaspartofthisstudy:

TM1 BoredTunnelGeometry

TM2 TunnelGroundCharacterization

TM3 TunnelExcavationMethods

TM4A PreliminaryDesignConceptsfortheFreewayTunnelandCrossPassageLinings

TM4B PreliminaryDesignConceptsfortheLRTTunnelandCrossPassageLinings

TM4C PreliminaryDesignConceptsfortheFreewayTunnelInternalStructure

TM5 EvaluationandControlofGroundMovements

TM6 PreliminaryDesignConceptsforFaultCrossings

TM7 PreliminaryDesignConceptsfortheFreewayPortalExcavationSupportSystems

TM8 PreliminaryDesignConceptsfortheLRTStationandPortalExcavationSupportSystems

TM9 HandlingandDisposalofExcavatedMaterials

1.3 Purpose and Limitations Thepurposeofthisreport,includingtheappendedTMs,istodocumentthepreliminarydesignevaluationsandconceptsdevelopedinsupportoftheenvironmentaldocumentationfortheSR710NorthStudy.Theseconceptsalsoserveasabasisforapreliminaryconstructioncostestimatedevelopedforthetunnelsections.

ThepreliminarydesignconceptspresentedineachTMwereconsideredinsubsequentenvironmentalstudies,andinmanycasesrepresentonefeasibleorlikelyoption.Otheroptionsshouldbeexplored,andtheconceptsshouldbetakentoafurtherlevelofrefinementinfuturephasesofthisstudyifeitheroftheboredtunnelalternativesiscarriedfurther.

Thepreliminarydesignconceptspresentedhereinarelimitedtothegeotechnicalinformationavailabletodate(CH2MHill,2014b).Conceptsareexpectedtobemodifiedandrefinedasadditionalgeotechnicalinformationbecomesavailable,includingtheoptimizationofthehorizontalandverticaltunnelalignments.However,suchmodificationsorrefinementsareexpectedtobewithintherangeofconstructionactivitiesalreadyconsideredanddiscussedintheenvironmentalstudies.ItshouldalsobenotedthateachTMalsocontainsrecommendationsorsuggestionsforadditionalworkthatwouldneedtobeconsideredinfuturedesignphases.

1 INTRODUCTION


FIGURE1LRTAlternative

1 INTRODUCTION


FIGURE2FreewayTunnelAlternative


Summary of Technical Memoranda TheTMspreparedforthetunnelsectionsofthisstageofthestudyaresummarizedbelow;eachTMisprovidedinitsentiretyasseparateappendicestothisreport.

2.1 TM-1: Bored Tunnel Geometry TM1presentsthecriteriausedandthedevelopmentprocessfollowedtodeterminethecrosssectionalgeometryfortheboredtunnelsaswellasrequirementsforspacingandsizingofcrosspassages,whereapplicable.

MetroandtheNationalFireProtectionAssociation(NFPA)havepublishedstandardsandguidelinesforLRTboredtunnelsthatwereconsultedindeterminingthecrosssectionoftheLRTtunnels.Metrocriteriaspecifyaninsidediameter(ID)foranLRTtunnelas18.83feetandalsoprovideclearanceenvelopesforlightrailboredtunnels.Theresultingouterdiameter(OD)ofthefinalliningisdeterminedtobeabout20.5feet.CrosspassagesareproposedalongtheLRTtunnelasemergencyexitsataspacingnottoexceed800feet,withaspacingof750feetbeingpreferred.Theclearanceenvelopeinsidethecrosspassagesis6.5feetwideand8feethigh,withaminimumheightof7feet.

Theboredtunnelconfigurationforthefreewayisgovernedbyregulatoryagencyrequirementsaswellasthespacerequiredforventilation,trafficoperations,andequipment.Thetunnelconfigurationislargelydeterminedbyrequiredhorizontalandverticalfreewayclearancesandotherusesoftunnelspace,suchasforemergencyegress,ventilationducts,drainage,communications,andutilities.Currentregulations,guidelines,andcriteriaestablishedbyCaltrans,FHWA,NFPA,andotherregulatingagencieswerereviewedwhendevelopingtheboredtunneldesignandconfiguration.Basedontheoperationalneedsandtheregulatoryrequirementsreviewedatthistime,itisexpectedthatthecomponentsofthefreewaytunnelfitwithinanIDof52.5feet.Thethicknessofthesegmentalliningshownatthispreliminaryphaseisexpectedtobe30inches,whichresultsinatunnelliningODofabout58.5feet.

EmergencyvehiclecrosspassagesarecurrentlybeingrecommendforthetwinboreFreewayTunnelAlternativeataspacingofapproximately3,000feet.Thesecrosspassagesareexpectedtobeusedtoprovidefirstresponderswithanalternatemethodtoreachanincident,possiblyreducingtheamountoftimeittakestoarriveatthelocationofanincidentintheeventofanemergencyorunplannedevent.Theemergencyvehiclecrosspassagesareexpectedtohaveaclearanceenvelopethatis20feetwideand14.5feethigh,andconstructedataskewanglesof50degreesbetweentheboredtunnels.Astherearetwolevelsoftraffic,therewouldbeaseparatecrosspassageforeachoftheupperandlowerlevels.

2.2 TM-2: Tunnel Ground Characterization TM2describestheresultsofevaluationsperformedtocharacterizegroundconditionsfortheboredtunnelsandcrosspassages,includingthedeterminationoftunnelreachesandidentificationofgroundclasses.Groundcharacterizationinvolvesevaluatingavailablegeologicdata,assessingsoil/rockmassproperties,identifyingdistinctrockmasstypes,estimatinganticipatedgroundbehaviorsalongtheproposedtunnelalignments,anddevelopinggeotechnicalparametersforpreliminarydesignevaluations.

Thesegeologicunits/formationsincludebothsoftgroundandrockformationsconsistingofartificialfill,alluvium,FernandoFormation,PuenteFormation,TopangaFormation,andbasementcomplexrocks(WilsonQuartzDiorite).GroundconditionsthatareexpectedtobeencounteredalongtheproposedFreewayandLRTtunnelalignmentshavebeendividedintofourgroundclassestoassistintheselectionoftunnelexcavationandsupportmethods.Groundclassesaredefinedbasedonthephysicalcharacteristicsofthegroundanditspotentialbehaviorsduringtunnelexcavation.Theyincludethefollowing(refertoTM2foradditionalinformation):

2 SUMMARY OF TECHNICAL MEMORANDA


GroundClass1:fairtogoodrockconditionsGroundClass2:poorrockconditionsGroundClass3:softgroundormixedfacegroundconditionsGroundClass4:faultedorshearedgroundconditions

2.3 TM-3: Tunnel Excavation Methods TM3presentsandevaluatesfeasibleexcavationmethodsfortheboredtunnelsandcrosspassages.Basedonthetunnellengthsandgroundconditions,excavationofthefreewayandLRTrunningtunnelsareexpectedtobeminedwithtunnelboringmachines(TBMs),andthecrosspassagesareexpectedtobeexcavatedusingthesequentialexcavationmethod(SEM).

TheLRTalternativealignmentisexpectedtobeexcavatedthroughconditionsthatvarybetweenalluviumandtheweaksedimentaryrockformation,andtheFreewayalternativeswouldbeexcavatedinthealluvium,thesedimentaryrockformations,andbasementrock.Bothboredtunnelalternativeswouldhaveportionsexpectedtobeexcavatedcompletelybelowthegroundwatertable.ApressurizedfaceTBMisideallysuitedfortheboredtunnelsduetothepotentialforhighgroundwaterpressurescombinedwiththevaryingpermeabilityandstrengthofthesoilunits,includingmixedfaceconditions.DifferenttypesofpressurizedfaceTBMsaredescribed,aswellastheirapplicabilitybasedongroundconditionsandotherfactors.

Unliketheboredtunnels,crosspassageswouldrequireinstallationofaninitialsupportsystemfollowedbyafinallining.TheSEMisflexiblefortunnelsinweakandvariablegroundconditionsandconsideredtobethemostsuitableandeconomicalmethodofconstructingthecrosspassages.Differentminingmethodstoexcavatethegroundarediscussed,aswellastheirapplicabilitytotheexpectedgroundconditionsinthecrosspassages.Additionally,theuseofsystematicgroundimprovementmeasurestostabilizetheopeningsandcontrolgroundmovementsandgroundwaterinflowsduringexcavationofthecrosspassagesarediscussed.

ThefollowingothertunnelexcavationconsiderationsarealsobrieflydiscussedinthisTM:

Constructionpowerrequirements Handlingpotentialmanmadeobstructions Contractorslaydownareas TBMabandonment(FreewayTunnelAlternativeonly)

2.4 TM-4A: Preliminary Design Concepts for the Freeway Tunnel and Cross Passage Linings

TM4AdescribespreliminarytunnelliningandcrosspassagedesignconceptsforthetwinboreandsingleborevariationsoftheFreewayTunnelAlternative.InthisTM,theapplicablecodesandguidelinestotunnelandcrosspassageliningdesignarediscussedaswellasothercriteriaincludingbutnotlimitedtoservicelife,durability,watertightness,andfireresistance.Thedesignloadsusedinthedevelopmentofthepreliminarydesignconceptsarealsoexplained,aswellastheloadingcombinationsandloadfactorsused.

Theresultsoftheanalysisindicatethata30inchthickprecastconcretesegmentalliningissufficienttowithstandtheloadingconditions,giventhecurrentgeotechnicalinformationavailable;however,itshouldbeexpectedthatthisdesignwillberefinedinfuturephasesofthisproject.ThecrosspassagesareexpectedtobeexcavatedusingtheSEM,asdiscussedinTM3,andwouldconsistofatwopassliningsystemoftheinitialshotcreteliningandthecastinplaceconcretefinallining.Forthepreliminarydesignconceptsoftheinitialsupport,groundconditionsatvariouscrosspassagelocationshavebeencategorizedintothreegroundclasses(outofthefourdiscussedinTM2).Eachgroundclassisexpectedtorespondsimilarlytotunnelingoperationsandwouldrequiresimilarinitialsupporttypes.Numericalanalyseswereperformedtodeterminepreliminaryconceptsfortheexcavationsequenceandinitialsupportrequirementsforeachgroundclass.Additionalnumericalanalyseswereperformedtodeterminethestaticandseismicrequirementsforthefinalliningofthecrosspassages.ThisTMalsodiscusses



otherdesignconsiderationssuchasthetemporarybreakoutsupportsequencingandrequirements,aswellasthepermanentringbeam,whichisexpectedtoberequiredwherethecrosspassagesinterfacewiththerunningtunnels.

2.5 TM-4B: Preliminary Design Concepts for the LRT Tunnel and Cross Passage Linings

TM4BdescribesthepreliminarydesignconceptsdevelopedfortunnelandcrosspassageliningsystemsfortheboredtunnelportionsoftheLRTAlternative.ThesedesignconceptsweredevelopedfromexperiencewithothersimilarLRTtunnelsintheLosAngelesarea.TheTMprovidesageneraldescriptionofthegeologyalongthetunnelalignment,aswellasdiscussionsofapplicabledesigncriteria,generalliningrequirements,andanoveralldesignmethodologythatcanbeappliedtotheLRTtunnels.InthisTM,theapplicablecodesandguidelinestotunnelandcrosspassageliningdesignaredetailed,aswellasothercriteriaincluding,butnotlimitedto,servicelife,durability,watertightness,andfireresistance.Thedesignloadsrecommendedforuseinthedevelopmentofthepreliminarydesignconceptsarealsoexplained,aswellasrecommendedloadingcombinationsandloadfactors.

Atthisstageofthedesign,theliningdesignconceptsfortheLRTtunnelsisbasedprimarilyonrelevantpastexperience,whichincludestheRegionalConnectorTransitCorridorandMetroGoldLineEastsideExtensionprojectsinLosAngeles,aswellastheUniversityLinkRailinSeattle,Washington.ThepreliminarydesignconceptfortheliningoftheLRTalternativeisagasketedsegmentalprecastreinforcedconcreteliningwithanapproximatethicknessof10inches;however,adetailedanalysisshouldbeperformedinfuturephasesofthisproject.SimilartothecrosspassagesoftheFreewayTunnelAlternative,thecrosspassagesfortheLRTAlternativeareexpectedtobeexcavatedusingtheSEM,andwouldconsistofatwopassliningsystemoftheinitialshotcreteliningandthecastinplaceconcretefinallining.DifferentsupporttypesbasedongroundclassesalongtheLRTalignmentaredetailedinthisTM,andrecommendedforthecrosspassageinitialsupport.ThepreliminarydesignconceptforthefinalliningoftheLRTcrosspassagesispresentedbasedonlocalexperienceonotherMetroprojects.

2.6 TM-4C: Preliminary Design Concepts for the Freeway Tunnel Internal Structure

TM4CdescribesthepreliminarydesignconceptsfortheinternalstructureelementsofthetwinboreandsingleborevariationsoftheFreewayTunnelAlternative.Theinternalstructureconsistsofthehorizontalandverticalelements(mainlyslabsandwalls)tobeconstructedwithinthetunnelaftertheexcavationisperformedandthesupportinstalled.Theseelementswouldeventuallymakeuptheroadwaydecksandthewallsseparatingthetravellanesfromtheemergencyexitwalkwaysandventilationducts.InthisTM,theapplicablecodesandguidelinestotunnelinternaldesignaredetailedaswellasothercriteriaincludingbutnotlimitedtoservicelife,durability,watertightness,andfireresistance.Thedesignloadsusedinthedevelopmentofthepreliminarydesignconceptsarealsoexplainedaswellastheloadingcombinationsandloadfactorsused.

Thepreliminarydesignconceptpresentedatthistimefortheinternalstructureconsistsofadoubledeckroadwayconstructedofcastinplace(CIP)andprecastreinforcedconcrete.Eachdeckhastwo12footwidetravellanes,a1footshoulder,anda10footshoulderforvehicles.Eachdeckalsohasawalkway,whichservesastheemergencyegressrouteintheeventofanemergencysuchasatunnelfire.Theresultsofthepreliminaryanalysisindicatethat26inchthickslabsfortheroadwaydecksand10to16inchthickwallsaresufficienttowithstandtheanticipatedloadingconditions.Thisanalysiswouldberefinedinfuturephasesofthisprojectasotherloadingssuchasdeadweightoftunnelsystemcomponentsthattheinternalstructurewouldsupportandvehiclecollisionloadsbecomebetterdefined.Theperformanceoftheinternalstructureswouldalsobeevaluatedfurthertoensureadequateresiliencetofires.Severalmeasuresarediscussedtoensurethesatisfactory



performanceoftheinternalstructurewhenexposedtofire.Thetypesoffireresistantelements/provisionsrequiredandtheirimpactontheventilationsystemswouldalsobeevaluatedfurther.

2.7 TM-5: Evaluation and Control of Ground Movements TM5discussesmethodsofevaluatingandcontrollingconstructioninducedsurfacegroundmovementsandpresentsamethodologytodeterminetheirpotentialeffectsalongtheproposedFreewayTunnelandLRTAlternatives.Apreliminaryanalysisofexcavationinducedgroundmovementshasbeenperformedusingsemiempiricalmethodstodeterminetheextentsofthezoneofpotentialexcavationinducedgroundmovementinfluence,whichisidentifiedinthisTM.

Thefocusoftheseevaluationsisonverticalgroundmovements.Theinducedgroundmovementswouldformasettlementtroughtransversetotheproposedboredtunnels,whichisestimatedusingasemiempiricalmethodthatassumesthattheshapeofthesettlementtroughaboveasingletunnelfollowsaGaussiandistributionandthatthevolumeofthesettlementtroughisequaltothetotalvolumeofgroundlostduringtunneling.Thetotalverticalgroundmovementscausedbytwotunnelsarethesumofthegroundmovementscausedbyeachindividualtunnel.Forthisstudy,avolumelossof0.5%wasadoptedforthealluviumand0.25%fortheweaksedimentaryrockformationsbasedoncasehistoriesofsimilarprojects.Forcutandcoverexcavations,associatedgroundmovementscanalsobeestimatedusingsemiempiricalmethodsbasedoncasehistoriesofgroundmovementnexttoexcavationsupportwalls.

SeveraloptionsforcontrolofgroundmovementthroughpreventionandmitigationarediscussedinthisTM.Overthepast10to15yearsintheU.S.,pressurizedfacemachineshavebeenusedastheprimarymitigationtoreducetheriskofexcessivegroundlossduringexcavation,aswellastominimizeoveralllossofground,andsubsequentgroundmovementsduetotunneling,ascomparedtotheuseofopenfacetunnelexcavationmethods.InadditiontorequiringtheuseofapressurizedfaceTBM,theprojectcouldalsospecifyrequirementssuchasselectingaprequalifiedcontractorwithexperienceminingwithpressurizedfaceTBMsandrequiringthatthegroundlossbelimitedtoacertainpercentage,andthatthecontractordemonstratethathecanachievethatgroundlosspercentagewiththemachineselected.Additionally,itcouldbespecifiedthatpracticessuchasmonitoringmuckvolumes,integratedtailvoidgrouting,andarealtimeinstrumentationandmonitoringprogrambeinplaceduringTBMexcavation.

Infurtherphasesofdesign,furtherevaluation,includingstructurespecificanalysis,wouldbeperformedtobetterunderstandtheresponseofthestructuresalongthepreferredalignmenttotheexcavationinducedgroundmovements.

2.8 TM-6: Preliminary Design Concepts for Fault Crossings TM6discussestheevaluationofthepreliminarydesignconceptsfortheportionsoftheboredtunnelsthatcrossactiveandpotentiallyactivefaultzonesalongthetunnelalignmentsfortheFreewayTunnelandLRTAlternatives.Becauseofthefaultoffsetexpectedatthesefaultzones,widenedtunnelcrosssections(calledvaultsections)areproposedtoaccommodatethefaultoffset.Thefocusofthediscussionisonthedesigncriteriaanddesignbasisrelatedtodesignconceptsforthefaultcrossingsandthedesignmethodologythatisemployedtoevaluateafeasiblefaultcrossingconceptforeachboredtunnelalternative.Sitespecificgeotechnicalinvestigationshaveyettobecompletedateachofthevariousfaultzones;futuredesignstudieswillrequiresitespecificdatatobeobtainedinordertorefinethedesignconceptsdiscussedherein.

TheFreewayTunnelAlternativeisanticipatedtocrossoneactiveandtwopotentiallyactivefaults:theRaymondfaultisconsideredanactivefault,whiletheEagleRockandSanRafaelfaultsaredesignatedaspotentiallyactive,butaretreatedasactiveinthisstudy.ThetunnelportionoftheLRTAlternativeisanticipatedtocrosstheRaymondandSanRafaelfaults.TheexpecteddesignhorizontalandverticaloffsetsforthesefaultsarediscussedinthisTM.Thesepotentialoffsetscouldinducesignificantstressesinthetunnellinings,resultingincrackingand



deformation(shearing)ofthelinings.Tominimizethedamage,specialdesignfeaturesmustbeincorporatedintothedesigntoaccommodatetheanticipatedgroundoffsetsandminimizetheimpactofpotentialoverstressinginthelinings.

Becauseofthemagnitudeofthedesignfaultoffsetsforthisstudy,specialdesignfeaturessuchasanenlargedvaultsectionorspecialliningdesignforthefaultcrossingsareconsideredtobenecessary.Anenlargedvaultsectionwitharobustliningsystemhasbeenchosenasoneviablepreliminarydesignconcepttomoveforwardwithinthisstudy.Inthisoption,structuralringswithcircumferentialjointsbetweenthemaredesignedtoallowslippageinthefaultzone,andtheenlargedcrosssectionwouldaccommodatethefaultoffset.

TheconceptfortheFreewayTunnelAlternativewouldconsistofinstallinghighstrengthsteelsegmentswithathicknessof20inchesinthefaultzone,ascomparedtothe30inchthickprecastconcretesegmentsusedfortheremainderoftheboredtunnel.Thedifferenceinthethicknessislargeenoughtoaccommodateboththehorizontalandverticalcomponentsofthefaultoffset,whilststillprovidingastrongersection.

Basedontheanticipatedfaultoffset,theLRTAlternativewouldrequireanoversizedvaultsectionbeexcavatedinthefaultzoneafterthecompletionoftheboredtunnels.Thevaultsectionwouldrequireoverexcavatingthesectionoftunnelwithinthefaultzonelargeenoughsothata36inchthickcastinplaceliningsectioncouldbeconstructed.Thecastinplaceliningwillbedesignedtoaccommodatetheexpectedfaultoffsets.Theseconceptswillbeexploredfurtheralongwithotheroptionsinfuturephasesoftheproject.

2.9 TM-7: Preliminary Design Concepts for the Freeway Portal Excavation Support Systems

TM7describesthepreliminarydesignconceptsdevelopedforexcavationsupportsystemsoftheconstructionportalsfortheFreewayTunnelAlternative.ConstructionportalsfortheFreewayTunnelAlternativewouldbelocatedateachendoftheboredportionofthetunnelalignment.BecauseminingmightoccurfrombothportalswithtwoTBMsexcavatingeachbore,bothportalswouldsupportconstructionactivitiesandalsoserveasalaydownareaforthecontractorduringconstruction.Theportalexcavationsareexpectedtoremainopenforthedurationoftunnelexcavationandconstruction,andultimatelypermanentroadwayfeatures(suchascutandcoverportionsofthetunnel)andpermanentportalstructureswillbeconstructedatthecompletionoftheproject;however,thepermanentworksarenotwithinthescopeofthisTM.

Thenorthportalexcavationforthetwinborevariationwouldbeapproximately250feetwideand80100feetdeepattheportalheadwallduetoanexistinggroundslope.Thesidewallsoftheportalwouldalsobeofasimilarheightneartheheadwall,andwoulddecreaseinheightasthefutureroadwaycontinuesnorthandtheexcavationbecomesshallower.ThewidthoftheexcavationissufficienttolaunchtwoTBMsandalsotoaccommodatethepermanentcutandcovertunnels,whichwouldbeconstructedafterexcavationoftheboredtunnels.Theexcavationforthenorthportalwouldbeentirelyinalluviumandfillandisnotexpectedtoencountergroundwater,sogroundwatercontrolmeasuresarenotexpectedtonotbenecessaryforportalexcavation.Asoldierpileandtimberlaggingwallsupportedwithtiebacksisconsideredsuitablefromaconstructabilityandstructuraldesignstandpoint,andisbeingassumedforthisportionofthestudy,thoughotheroptionsmaybefeasible.

Similartothenorthportal,thesouthportalexcavationforthetwinborevariationwouldbeapproximately250feetwideand125feetdeep.Thesubsurfaceconditionsconsistof25to60feetofloosetoverydensealluviumunderlainbythePuenteFormation.Thewatertableisapproximately25feetbelowthecurrentgroundsurfacethroughouttheportalexcavation.PrimarydesignconsiderationsatthesouthportalincludegroundwatercontrolandthelongtermstrengthandbehaviorofthePuenteFormation.Dewateringmaybeconsideredforgroundwatercontrol,orwallsystemscanbeusedtocutoffwaterfromtheexcavation.TherocklikefracturedandjointedportionofthePuenteFormation,ifencounteredatthebase,mayrequirebasegrouting(permeationorpressuregrouting)inordertosealoffthejointsandfracturesfromgroundwaterinflows.Slurrywallswith



tiebacksareconsideredasuitablesupportofexcavationmethodgiventhedepthofwallinstallationandthepresenceofgroundwater,thoughotheroptionsmaybefeasible.

Thepreliminarydesignconceptsfortheportalsforthesingleborevariationaresimilarindepthandconcepttothosedescribedforthetwinborevariation,butthewidthisreducedbyapproximately115feettoaccommodatethesingletunnelboreandonlyoneTBMperportal.

2.10 TM-8: Preliminary Design Concepts for the LRT Station and Portal Excavation Support Systems

TM8describesthepreliminarydesignconceptsdevelopedfortheexcavationsupportsystemsfortheLRTsouthconstructionportalandfourundergroundLRTstationexcavations.TheboredtunnelsoftheLRTAlternativeareexpectedtobeminedusingtwoTBMslaunchedfromthesouthportal,andthatportalwouldalsobeusedtostageconstructionactivitiesforthetunnelingwork.FourundergroundstationsareexpectedtobeexcavatedusingcutandcovertechniquesinadvanceoftheTBMarrivalateachlocation;itiscommonthatthestationsareexcavatedfirst,butisnotnecessaryandwilldependonprojectrequirements.ThealignmentterminatesattheFillmoreStation,andtheTBMswouldberetrievedfromthatlocation.Thefinal,permanentstructurestobeconstructedwithinthetemporaryexcavationsdiscussedinthisTMarenotaddressedinthisTM.

Theportalexcavationisapproximately50feethighand70feetwideattheheadwall.Thesidewallsofthetemporaryexcavationwouldbeofasimilarheightneartheheadwall,andwoulddecreaseinheighttothesouthastheexcavationbecomesshallower.TheportalwouldrampdownfromtheexistinggroundsurfacetogainenoughcovertolaunchtheTBMs;bothTBMsfortheLRTalternativewouldbelaunchedattheheadwallofthisportal.Geotechnicalconditionsindicatealluvialsoilswithintheexcavatedheightandthatgroundwatercouldpotentiallybeencounteredinthedeeperportionoftheexcavationneartheportalheadwall.Preliminarydesignconsiderationswouldbepreventingthealluviumfromsloughingintotheexcavation,andasecondaryconsiderationwouldbecontrollinggroundwaterneartheportalheadwall,ifencountered.Asoldierpileandtimberlaggingwallsupportedwithtiebacksisconsideredsuitablefromaconstructabilityandstructuraldesignstandpoint;however,otheroptionsmaybefeasible.

Therearefourundergroundstations,whichareexpectedtobeexcavatedwithcutandcovertechniques;theseincludetheAlhambraStation,HuntingtonStation,SouthPasadenaStation,andFillmoreStation.Thestationexcavationsareapproximately80to100feetdeepand80feetwide,withthelengthofeachstationexcavationvaryingfrom400feetforastandardstation,uptoover1,000feetifthereisacrossoverortailtracksadjacenttoit(theHuntingtonStationincludesanexcavationforacrossoverandtheFillmoreStationincludesanexcavationfortailtracks).Atthefourstations,thegeotechnicalconditionsindicatethattheyareexpectedtobeexcavatedwhollyinalluvialsoilsorinacombinationofalluvialsoilsandweaksedimentaryrock.TheAlhambraStationisexpectedtohavegroundwaterinthebottom20feetoftheexcavation.Allstationsareexcavatedinanurbansettinginthepublicrightofwaywithbuildingsandstructuresimmediatelyadjacenttotheexcavations.

SoldierpilesandlagginghavebeensuccessfullyusedforpastMetroprojectsundersimilarconditionsandthereforehavebeenselectedasthewalltypeatthisconceptualdesignlevel.Tiebacksand/orinternalbracingcanbeusedforlateralwallsupport.Tiebackscanbeinstalledthroughthesoldierpileitself,andinternalbracing,ifused,wouldconsistofwalersandstruts.SimilartoTM7,thisTMalsoincludesadiscussionofgroundsupportattheportal,andstation,headwallstosupportbreakinandbreakoutoftheTBMs.

2.11 TM-9: Handling and Disposal of Excavated Materials TM9describesseveralaspectsofhandlinganddisposalofexcavatedmaterialsfortheFreewayandLRTalternatives.TheFreewayandLRTboredtunnelswouldbeminedwithTBMs,andtheexcavatedmaterialgeneratedfromthetunnelingoperationswouldberemovedattheportals.Inadditiontotheboredtunnels,excavationofconstructionportals,crosspassages,andLRTstationswouldalsogeneratespoilmaterial.



ThisTMevaluatestheanticipatedproperties(includingbulkingfactors)forexcavatedmaterialsbasedonthegeologicformationsalongthetunnelalignments.Bulkingfactorsandunitweightshavebeenestimatedforeachgeologicunitexpectedtobeencounteredintheexcavation;assumedbulkingfactorsrangefrom1.3to1.6.Estimatesofapproximatequantitiesandweightsofexcavatedmaterialthatwouldbegeneratedfromthetunnel,portal,andLRTstationexcavationsforeachalternativearepresentedbasedonthepercentageoftheexcavationineachgeologicunit.Theseestimatesarepresentedastotalvolumesandweightsforeachcomponentoftheexcavationprocess.

AdiscussionoftheanticipatedexcavatedmaterialconditionsfromTBMtunnelingoperations(includingthoseresultingfromconditioningadditives)andthehandlingofexcavatedmaterialattheworkareasisalsoincludedinthisTM.


References CH2MHill(2012),StateRoute710StudyAlternativesAnalysisReport.PreparedforMetro.December.CH2MHill(2014a),SR710NorthStudyAdvancedConceptualEngineeringReportLRTAlternative.PreparedforMetro.April.CH2MHill(2014b),SR710NorthStudyDraftPreliminaryGeotechnicalReport.PreparedforMetro.August.CH2MHill(2014c),SR710NorthStudyDraftProjectReport.PreparedforMetro.August.

Appendix A TM- 1 Bored Tunnel Geometry

T E C H N I C A L M E M O R A N D U M 1 Bored Tunnel Geometry PREPARED FOR: MetroCOPY TO: CaltransPREPARED BY: JacobsAssociates/CH2MHILLDATE: August22,2014PROJECT NUMBER: 428908

1 Introduction 1.1 Project Description AspartoftheStateRoute(SR)710NorthStudy,fivealternativesarebeingevaluatedaspartofanongoingenvironmentaldocumentationprocess.TheproposedalternativesincludetheNoBuildAlternative,theTransportationSystemManagement/TransportationDemandManagement(TSM/TDM)Alternative,theBusRapidTransit(BRT)Alternative,theLightRailTransit(LRT)Alternative,andtheFreewayTunnelAlternative.TheFreewayTunnelandLRTAlternativeswillinvolvetunnelsforsignificantdistancesovertheiralignments.

TheLRTAlternativewouldincludepassengerrailoperatedalongadedicatedguideway,similartootherMetrolightraillines.TheLRTalignmentisapproximately7.5milong,with3miofaerialsegmentsand4.5miofboredtunnelsegments.TheLRTAlternativewouldbeginatanaerialstationonMednikAvenueadjacenttotheexistingEastLosAngelesCivicCenterStationontheMetroGoldLineandcontinuesnorthtoendatanundergroundstationbeneathRaymondAvenueadjacenttotheexistingFillmoreStationontheMetroGoldLine.Twodirectionaltunnelsareproposedwithtunneldiametersapproximately20feeteach.SevenstationswouldbelocatedalongtheLRTalignment;ofthese,theAlhambraStation,theHuntingtonStation,theSouthPasadenaStation,andtheFillmoreStationwouldbeundergroundstations.

ThealignmentfortheFreewayTunnelAlternativestartsattheexistingsouthernstubofSR710inAlhambra,justnorthofI10,andconnectstotheexistingnorthernstubofSR710,southoftheI210/SR134interchangeinPasadena.TheFreewayTunnelAlternativehastwodesignvariations:atwinboretunnelandasingleboretunnel.Thetwinboretunnelvariationisapproximately6.3milong,with4.2miofboredtunnel,0.7miofcutandcovertunnel,and1.4miofatgradesegments.Thetwinboretunnelvariationwouldconsistoftwosidebysidetunnels(onenorthbound,onesouthbound),eachtunnelofwhichwouldhavetwolevels.Eachtunnelwouldconsistoftwolanesoftrafficoneachlevel,travelinginonedirection,foratotaloffourlanesineachtunnel.Eachboredtunnelwouldhaveanoutsidediameterofapproximately60feet.Thesingleboretunneldesignvariationissimilarinlengthanddiameter;however,thesingleboretunnelvariationwouldconsistofonetunnelwithtwolevels.Thenorthboundtrafficwouldtraversetheupperlevel,andthesouthboundtrafficwouldtraversethelowerlevel.

1.2 Task Description and Scope Thistechnicalmemorandum(TM)presentsthebackgroundonthedevelopmentofthecrosssectionfortheboredtunnelforboththeFreewayTunnelandLRTAlternatives.Applicablecodes,standardsandassumptionsmade

BORED TUNNEL GEOMETRY

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duringtheprocessaredocumentedherein.RequirementsforcrosspassagesforthetwinborefreewaytunnelandtheLRTtunnelwillalsobediscussed.ThisTMdoesnotdocumenttheroadwaydesign,ventilation,ortunnelsystemsdesignsexceptwheresuchrequirementsaffectthediameteroftheboredtunnel.ThecrosssectionofthecutandcoverportionsofthefreewayandLRTtunnelsisnotwithinthescopeofthisTM.

1.3 Purpose ThepurposeofthisTMistodocumentpreliminarydesignevaluationsandconceptsdevelopedinsupportoftheenvironmentaldocumentationfortheSR710NorthStudy.Theseconceptsalsoserveasabasisforpreliminaryconstructioncostestimate,developedforthetunnelsections.

ThepreliminarydesignconceptspresentedinthisTMwillbeconsideredinsubsequentenvironmentalstudies,andinmanycasesrepresentonefeasibleorlikelyoption.Otheroptionsshouldbeexplored,andtheconceptsshouldbetakentoafurtherlevelofrefinement,infuturephasesofthisstudyifeitheroftheboredtunnelalternativesiscarriedfurther.

2 Freeway Tunnel Cross Section Geometric Requirements FortheFreewayTunnelAlternative,theboredtunnelconfigurationisgovernedbyregulatoryagencyrequirementsaswellasthespacerequiredforventilation,trafficoperations,andequipment.Thetunnelconfigurationislargelydeterminedbyrequiredhorizontalandverticalfreewayclearancesandotherusesoftunnelspace,suchasforemergencyegress,ventilationducts,drainage,communications,andutilities.

Currentregulations,guidelines,andcriteriaestablishedbyCaltrans,FHWA,andotherregulatingagencies,outlinedbelow,werereviewedwhendevelopingtheboredtunneldesignandconfiguration.Itshouldberecognizedthattunnelsofthissizeandlengtharenotroutine,sothereislittleprecedenttodrawfrom.TwotunnelsthatwereconsideredasabasisforsomeoftheallowancesweretheCaldecott4thBoreTunnelandDevilsSlideTunnel,bothinnorthernCalifornia;theseareCaltransmostrecenthighwaytunnels.Additionally,theSR99Tunnel,whichiscurrentlyunderconstructioninSeattle,Washington,wasalsoreferencedasabasisforcomparison.Itisimportanttonotethatengineeringstandardsandapplicableregulationsthatdopertaintotunnelsofthissizechangewithtime;therefore,itwillbeimportanttorevisitthecriteriaastheprojectproceedsthroughtheplanning,design,andenvironmentalreviewphases.

Chapter300oftheCaltransHighwayDesignManual(HDM),GeometricCrossSection,providesguidanceondimensionsforroadwaywidth,shoulders,andotherhorizontalandverticalclearances(Caltrans,2012).Additionally,theUSDepartmentofTransportationFederalHighwayAdministrations(FHWA)TechnicalManualforDesignandConstructionofRoadTunnels(2009)wasreviewed.RequirementsfromtheAmericanswithDisabilitiesAct(ADA,2002)andNationalFireProtectionAssociation(NFPA)werealsoconsulted.

ThefollowingsectionsdocumenttherequirementsthatwereconsideredindeterminingtheconceptualcrosssectionfortheFreewayTunnelAlternative.

2.1 Project Requirements Twooptionsarebeingconsideredforthisstudyatwinboretunnelandasingleboretunnel.Inthetwinboreconfiguration,theprojectwouldhavefourlanesoftrafficineachdirection(twolanesoneachlevel),onedirectionperbore,foratotalofeightlanes.Inthesingleboreoption,therewouldbetwolanesoftrafficineitherdirection,(twolanesontheupperlevelandtwolanesonthelowerlevel)foratotaloffourlanes.2.2 Travel Lanes InaccordancewithIndex301.1oftheCaltransHDM(2012),thestandardlanewidthshouldbe12feetperlane.ThisisconsistentwiththerecommendationfromtheFHWA(2009).Atravellanewidthof12feethasbeenadoptedforthisstudy.


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2.3 Shoulders TheFHWAandCaltransguidelinesaswellasotherexistingtunnelswerereferencedindeterminingrequirementsforshoulderwidths.Section2.4.2,TravelLaneandShoulderofTheFHWATechnicalManualforDesignandConstructionofRoadTunnelsstates:

AlthoughtheGreenBookstatesthatitispreferabletocarrythefullleftandrightshoulderwidthsoftheapproachfreewaythroughthetunnel,italsorecognizesthatthecostofprovidingfullshoulderwidthsmaybeprohibitive.Reductionofshoulderwidthinroadtunnelsisusual.Incertainsituationsnarrowshouldersareprovidedononeorbothsides.Sometimesshouldersareeliminatedcompletelyandreplacedbybarriers.BasedonastudyconductedbyWorldRoadAssociation(PIARC)andpublishedareportentitled"CrossSectionGeometryinUnidirectionalRoadTunnels"2001;shoulderwidthsvaryfromcountrytocountryandtheyrangefrom0to2.75m(9ft).Theyaregenerallyintherangeof1m(3.3ft).Itissuggestedforunidirectionalroadtunnelsthattherightshoulderbeat4ft(12m)andleftshoulderatleast2ft(0.6m).

ShoulderrequirementsfromIndex309.3,TunnelClearances,oftheCaltransHDMwerealsoconsulted.Index309.3statesthefollowingfortunnels:

Tunnelconstructionissoinfrequentandcostlythatthehorizontalwidthshouldbeconsideredonanindividualbasis.ForminimumwidthstandardsforfreewaytunnelsseeIndex309.1.

AtthedirectionofMetro,whichconsidersthedirectionfromtheFHWAandtheCaltransHDMaswellasprecedentfromexistingtunnels,thedesignwidthsoftheshouldersforthisstudywillbe1and10feet.Toallowforthewidershouldertobeonthesideoftheroadwaywithaccesstoemergencyegress,the10footshouldermaybelocatedontheleftsideofthetravellanesdependingontheconfigurationofthelanes.EmergencyegressisdiscussedinfollowingsectionsofthisTM.2.4 Edge Treatment ACaltransType60Dshapedbarrierwouldbeincorporatedintothewallshapeontheouteredgesofboththeleftandrightshoulders.TheType60DshapedbarrierwouldbemadeanintegralpartoftheverticalwallswhichseparatethetraveledwayfromotherareasofthetunnelasseeninAttachmentA.ThedimensionsoftheCaltransType60DbarrierareshowninFigure1.Thebarrierextends5.75inchesfromtheverticalwallatitsbase,andthe4inchhorizontalsurfacewouldbeincludedaspartoftheverticalwalls.

FIGURE 1 Caltrans Type 60D Barrier 2.5 Roadway Cross Slope Acrossslopeof2%isbeingshownforboththeupperandlowerroadways.Theroadwaysslopeawayfromtheemergencyegressareas.


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2.6 Vertical Clearance Theverticalclearanceisdeterminedbytheclearheightabovethehighwaygradefortraffic.CaltransHDMTable309.2A,MinimumVerticalClearances,indicatesthatafreeway(newconstruction)isrequiredtohaveaminimumverticalclearanceabovethetravellanesandshouldersof16.5feet.Additionally,theverticalclearancerequiredtosignsandminorstructuresis18.5feetforanormalatgradefreeway.Forthepurposesofdevelopingthetunnelcrosssectionsforthisstudy,averticalclearanceof15.5feet,withareducedclearanceof14feet8inchesforawidthof11inchesabovetheshoulderontheupperdeck,wasusedperMetrosdirection(refertoAttachmentA).

Ifamaximumpostedvehicleheightof14feetisusedforthetunnels,thiswouldprovideaclearanceofabout1.5feetbetweenthetopofavehicleandthelowestofanyappurtenanceinstalledinthetunnelbasedontheconfigurationproposed.Outsideofthisverticalclearanceenvelope,anadditional2feet(intheverticaldirectionabovetheclearanceenvelope)havebeenprovidedforsignage,lighting,andothertunnelsystemsequipment.

2.7 Emergency Egress Asafeevacuationrouteforvehicleoccupantsisessentialinthecaseofanemergencyinsideafreewaytunnel.TheNFPAstatesthatemergencyexitsmustbeprovidedthroughoutthetunneltominimizetheexposureoftheevacuatingvehicleoccupantstoanuntenableenvironment(NFPA502,2011).Inaddition,itmustberecognizedthatsomeofthevehicleoccupantsmaybedisabled,requiringspecialprovisions.TherequirementsthatformthebasisfortheegressconceptsoftheFreewayTunnelAlternativearebasedonbothNFPA(2011)andthediscussionswiththeCityofLosAngelesfiremarshalandotherstakeholders(CH2MHILL2013),andtheyincludethefollowing:

Spacingbetweentheemergencyexitsshallnotexceed656feet.

Theegresspassagewaysshallbeseparatedfromthetunnelwithaminimumofa2hourfirerateddoor/enclosure.

Theminimumclearwidthoftheegresspassagewaymustbe3.6feet.

Theminimumheadroomintheegresspassagewaysshallbe7.5feet,withprojectionsnotlessthan6.67feetabovethefloor.

Wheretheportalsofthetunnelarebelowsurfacegrade,thesurfacegradeshallbemadeaccessiblebyastair,ramp,orelevator.

Thedesignteamhastakentheserequirementsintoconsiderationtodeveloptheconceptforemergencyegressinboththetwinboreandsingleborefreewaytunneloptions.

2.8 Area for Tunnel Systems Equipment and Ventilation Thedesignofthetunnelsectionhasbeencheckedtoensurethatthereissufficientareainthecrosssectionforfirelifesafety,ventilation,andtunnelsystemsequipment.Thereisaminimumof2feetofclearspaceabovetheclearanceenvelopeoverthetravellanesfortunnellighting,variablemessagesigns,andothernecessaryutilities.Additionally,theventilationdesignwascheckedtoensureenoughareaisprovidedfortheexhaustairductandtheroomsfortunnelequipment;Nojetfansarenecessaryintheboredsectionofthistunnel.

2.9 Internal Structure Theinternalstructurethatwouldmakeuptheroaddecksandthewallswhichseparatethetravellanesfromotherareasofthetunnels(emergencyegresswalkwaysandutilitycorridors)willalsoaddtothespacerequirementsofthetunnel.Thethicknessesoftheverticalandhorizontalmemberswhichmakeuptheinternalstructurearesomewhatdependentofthefinaldiameterofthetunnel,makingitaniterativeprocess.Atthispreliminarystageofthedesign,thefollowingthicknessallowanceswereusedasabasisforthespacerequirements:

Roadwayslabthickness:26inches

Lowerwallthickness:16inches


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Upperwallthickness:10inches

AdditionaldetailsoftheinternalstructurecanbefoundinPreliminaryDesignConceptsfortheFreewayInternalStructure(JA2014c).

3 Freeway Tunnel Cross Section 3.1 Development Process Therequirementsdiscussedintheprevioussectionwereconsideredwhendeterminingthecrosssectionofthefreewaytunnel.Theactivityoffittingtogetherthetunnelcrosssectioninthemostefficientwaypossibleisaniterativeprocessthetaskwastofitthecomponentstogetherinawaythatmettherequirementsandfitinthesmallestdiameterpossible.Thegeometrythatresultedfromthisprocesshassufficientspaceforthetunnelsystemsequipmentandventilationandthereforeacrosssectionwasestablished.RefertoAttachmentAforthecrosssectionsofboththetwinandsingleborefreewaytunneloptions.

3.2 Tunnel Diameter Thecomponentsofthefreewaytunnelfitwithinadiameterthatis52.5feet;thesearethedesignlimitsofthecrosssection(refertoAttachmentA).ToaccountfordeviationsfromlineandgradeduringTBMexcavation,atoleranceof6incheswasallowed,andthereforethesegmentalliningisshownwithaninsidediameter(ID)of53.5feet(6inchtoleranceontheradiusresultsin1foottoleranceonthediameter).

Theoutsidediameter(OD)ofthetunnelsegmentalliningisdependentontheIDandthethicknessofthesegmentallining.Thethicknessofthesegmentalliningshownatthispreliminaryphaseis30inches(JA,2014a),whichresultsinaliningODof58.5feet.

WhilethefreewaytunnelcrosssectionhasanIDandODofthesegmentalliningof53.5and58.5feet,respectively,thediameteroftheTBMusedtoexcavateatunnelofthissizewouldbelarger.TheTBMisgenerallylargerthantheODoftheliningtoaccountforthethicknessoftheTBMshield,shieldclearance/gap,andovercut.Forexample,theSR99tunnelcurrentlyunderconstructioninSeattle,Washington,theexcavateddiameterisabout18incheslargerthantheODofthelining.Conceptually,aTBMwithanexcavateddiameterofapproximately60feet(i.e.,58.5feet+18inches)couldbeusedtoexcavatethefreewaytunnels.Thisisthediameterbeingusedforthisphaseofthestudyandshouldbeoptimizedwherepossibleinfuturestages.

3.3 Tunnel Bore Spacing Thetwotunnelboresareseparatedbyapproximatelyonetunneldiameterforthemajorityofthealignment,whichisapproximately60feet.Forreasonstodowiththeroadwaydevelopment,theboresareseparatedbyapproximately70feetastheyapproachthenorthTBMlaunchportal.Thisspacingshouldberevisitedinsubsequentphasesofthedesign;ifthespacingcouldbereduced,thelengthofthecrosspassageswouldbereduced.

4 Freeway Tunnel Emergency Vehicle Cross Passages 4.1 Background Emergencyvehiclecrosspassagesarebeingrecommendtobeincludedwiththetwinborevariation;thefollowingsectiondoesnotapplytothesingleborevariation.TherearenoregulationsintheCaltransHighwayDesignManualorsetbyNationalFireProtectionAssociation(NFPA)oranyotheragencyrequiringcrosspassagesforemergencyvehicles.However,itwasdecidedinacoordinationmeetingwiththeCityofLosAngelesfiremarshalandotherstakeholdersthatemergencyvehiclecrosspassageswouldbepositionedalongthetwinborevariationataspacingofapproximately3,000feetforthisstudy.(CH2MHILL2013)Theemergencyvehiclecrosspassagescouldreducetheamountoftimeittakesfirstresponderstoarriveatthelocationofanincidentintheeventofanemergencyorunplannedeventinatunnelofthislengthdependingonthelocationoftheincidentwithrespecttotheportalsandcrosspassages.Vehicularcrosspassageswouldprovidefirstresponderswithanotheroptiontoreachanincidentinadditiontotheshouldersofthetravellanes,


TM 1 R4.DOCX 6

andalsoprovideameansforvehiclesbehindtheincidenttoexitthetunnel.Theneedforthesecrosspassageswillcontinuetobediscussedinfuturephasesofthisproject.

4.2 Geometry and Configuration Thesizeofthecrosspassagesdependsonthetypeofvehiclesexpectedtousethem.Thecrosspassagesareprimarilyintendedforemergencyresponsevehicles;however,inameetingwiththefiremarshalitwasdeterminedthatthecrosspassagesshouldbeabletoaccommodatevehiclestravelinginthetunnelintheeventofanemergency,whichincludelargertrucks(CH2MHILL2013).

Angledcrosspassageshavebeenproposedtoaccommodatetheturningradiusofalargertruck.Aniterativeprocesswasusedtodeterminethewidthoftheclearanceenvelopeandtheangleofthecrosspassagewithrespecttotheboredtunneltooptimizethedesign.Theemergencyvehiclecrosspassagesareconceptuallyshowntohaveaclearanceenvelopethatis20feetwideand14.5feethigh,angled50degreesfromtheboredtunnels(Mitry2013).Theangleofthecrosspassagesshouldberevisitedwhenbettergroundinformationisavailable,andtheoperationalneedshouldanalyzedtooptimizethesafeandeconomicconstructionofthecrosspassagesinfuturephasesofthisstudy.RefertoAttachmentAfordrawingsofthecrosspassagesincrosssection.

Astherearetwolevelsoftraffic,therewouldbeaseparatecrosspassageforeachoftheupperandlowerlevels;onecrosspassageexcavationtoaccommodatebothlevelswouldrequiretoolargeofanexcavation.RefertoFigure2foraschematicofthecrosspassageconfigurationusedinthisstudy.Infuturephasesofthisproject,ifthecrosspassagesarecarriedforward,coordinationwillbeneededtodeterminehowthecrosspassageswillworktogetherwiththeemergencyegresspassagewayswhentheyareinuse..

FIGURE 2 3D Model of Emergency Vehicle Cross Passage Configuration

5 LRT Tunnel Geometric Requirements 5.1 Bored Tunnels MetrohaspublishedstandardsandguidelinesforLRTcircular(bored)tunnels(Metro,2012).Inaddition,theNFPA130codeforpassengerrailsystems(2010)wasalsoconsultedindeterminingthecrosssectionofthesetunnels.TheMetroRailDesignCriteria(2012)specifiesthattheIDofanLRTtunnelis18.83feetandpresentsfiguresshowingclearanceenvelopes.ThedrawingsinAttachmentBshowtheconceptualLRTTunnelcrosssection.Currently,theODofthefinalliningisshowntobe20.5feetbasedonasegmentalliningthatis10inchesthick(refertoJA,2014bfordetailsonthesegmentalliningoftheLRTtunnel).TheTBMthatwouldexcavateatunnelwithafinalliningofthissizewouldbeapproximately12to14inchesgreaterindiameterthantheODofthefinallining,makingitjustover21.5feetindiameter.


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5.2 Emergency Egress Awalkwayrunningtheentirelongitudinallengthofthetunnelisnecessarytoprovidepassengersaccesstoegresslocationsintheeventofanemergency.NFPA130(2012)requiresthattheminimumunobstructedwalkwaybeatleast30incheswideand80incheshigh.TheFire/LifeSafetyCriteriaoftheMetroRailDesignCriteria(2012)notethata30inchclearwidthisacceptable,anda36inchclearwidthispreferable.TheproposedclearanceenvelopefortheLRTwalkwaymeetstheserequirements(refertoAttachmentB).

CrosspassagesareproposedalongtheboredtunnelportionoftheLRTAlternativeasemergencyexitsataspacingnottoexceed800feet,withaspacingof750feetbeingpreferred.Theclearanceenvelopeinsidethecrosspassagesis6.5feetwideand8feethigh,withaminimumheightof7feet(MetroRailDesignCriteria,2012).TheserequirementsexceedtheNFPArequirementsforcrosspassagespacingandclearanceenvelopesize.DetailsregardingtheexcavationandsupportofthesecrosspassagesareinPreliminaryDesignConceptsfortheLRTTunnelandCrossPassageLinings(JA,2014b).

5.3 Bored Tunnel Separation TheseparationoftheLRTtunnelsvariesfromapproximately14to21feetalongthealignment.Thetwoboresareseparatedbyapproximatelyonetunneldiameterforthemajorityofthealignment,whichmakesthedistancebetweenthecenterlinesofeachtunnelboreapproximately42feet.Theseparationisreducedneartothefourundergroundstationswheretheborestaperintothestations(whichisdictatedbytheplatformwidth);thedistancebetweenthecenterlinesoftheboresattheselocationsisapproximately34.5feet.Inaddition,theboredtunnelstapertogetheratthenorthportal,wherethetunnelstransitionfromboredtunneltocutandcovertunnel.


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6 References ADAAccessibilityGuidelines(2002),basedonAmericanswithDisabilitiesActof1990.http://www.accessboard.gov/guidelinesandstandards/buildingsandsites/abouttheadastandards/background/adaag.

CaliforniaDepartmentofTransportation(Caltrans),2012.HighwayDesignManual(HDM).http://www.dot.ca.gov/hq/oppd/hdm/hdmtoc.htm.

CH2MHILL.2013.MinutesfromCoordinationMeetingwithFireMarshal.May21.

FederalHighwayAdministration(FHWA),2009.TechnicalManualforDesignandConstructionofRoadTunnelsCivilElements(FHWANHI10034),U.S.DepartmentofTransportation,March2009.

JacobsAssociates(JA).2014a.PreliminaryDesignConceptsfortheFreewayTunnelandCrossPassageLinings.PreparedforMetro..

JacobsAssociates(JA).2014b.PreliminaryDesignConceptsfortheLRTTunnelandCrossPassageLinings.PreparedforMetro..

JacobsAssociates(JA).2014c.PreliminaryDesignConceptsfortheFreewayInternalStructure.PreparedforMetro..

LosAngelesMetropolitanTransportationAuthority,MetroRailDesignCriteria.RevisedOctober16,2012.

Mitry,Ryan.2013.VehicleCrossPassages.[email]MessagetoTorsiello,Michael.SentJune6.

NationalFireProtectionAssociation(NFPA),2010.NFPA130:StandardforFixedGuidewayTransitandPassengerRailSystems,2010Edition.

NationalFireProtectionAssociation(NFPA),2011.NFPA502:StandardforRoadTunnels,Bridges,andOtherLimitedAccessHighways,2011Edition.

NationalFireProtectionAssociation(NFPA),2009.NFPA101:LifeSafetyCode,2009Edition.

7 Revision Log Revision0 January23,2014 InternalReview

Revision1 February6,2014 InternalReview

Revision2 February18,2014 Metro/CaltransReview

Revision3 June3,2014 Metro/CaltransReview

Revision4 August22,2014 IncorporationintoTunnelEvaluationReport

Attachment A Freeway Tunnel Drawings

Attachment B LRT Tunnel Drawings

Appendix B TM- 2 Tunnel Ground Characterization

TM 2 R3.DOCX

T E C H N I C A L M E M O R A N D U M 2

Tunnel Ground Characterization PREPARED FOR: MetroCOPY TO: CaltransPREPARED BY: JacobsAssociates/CH2MHILLDATE: August22,2014PROJECT NUMBER: 428908

1. Introduction 1.1 Project Description AspartoftheStateRoute(SR)710NorthStudy,fivealternativesarebeingevaluatedaspartofanongoingenvironmentaldocumentationprocess.TheproposedalternativesincludetheNoBuildAlternative,theTransportationSystemManagement/TransportationDemandManagement(TSM/TDM)Alternative,theBusRapidTransit(BRT)Alternative,theLightRailTransit(LRT)Alternative,andtheFreewayTunnelAlternative.TheFreewayTunnelandLRTAlternativeswillinvolvetunnelsforsignificantdistancesovertheiralignments.

TheLRTAlternativewouldincludepassengerrailoperatedalongadedicatedguideway,similartootherMetrolightraillines.TheLRTalignmentisapproximately7.5milong,with3miofaerialsegmentsand4.5miofboredtunnelsegments.TheLRTAlternativewouldbeginatanaerialstationonMednikAvenueadjacenttotheexistingEastLosAngelesCivicCenterStationontheMetroGoldLineandcontinuesnorthtoendatanundergroundstationbeneathRaymondAvenueadjacenttotheexistingFillmoreStationontheMetroGoldLine.Twodirectionaltunnelsareproposedwithtunneldiametersapproximately20feeteach.SevenstationswouldbelocatedalongtheLRTalignment;ofthese,theAlhambraStation,theHuntingtonStation,theSouthPasadenaStation,andtheFillmoreStationwouldbeundergroundstations.

ThealignmentfortheFreewayTunnelAlternativestartsattheexistingsouthernstubofSR710inAlhambra,justnorthofI10,andconnectstotheexistingnorthernstubofSR710,southoftheI210/SR134interchangeinPasadena.TheFreewayTunnelAlternativehastwodesignvariations:atwinboretunnelandasingleboretunnel.Thetwinboretunnelvariationisapproximately6.3milong,with4.2miofboredtunnel,0.7miofcutandcovertunnel,and1.4miofatgradesegments.Thetwinboretunnelvariationwouldconsistoftwosidebysidetunnels(onenorthbound,onesouthbound),eachtunnelofwhichwouldhavetwolevels.Eachtunnelwouldconsistoftwolanesoftrafficoneachlevel,travelinginonedirection,foratotaloffourlanesineachtunnel.Eachboredtunnelwouldhaveanoutsidediameterofapproximately60feet.Thesingleboretunneldesignvariationissimilarinlengthanddiameter;however,thesingleboretunnelvariationwouldconsistofonetunnelwithtwolevels.Thenorthboundtrafficwouldtraversetheupperlevel,andthesouthboundtrafficwouldtraversethelowerlevel.

1.2 Task Description and Scope Thistechnicalmemorandum(TM)presentsapreliminaryassessmentofthegroundconditionsalongtheboredportionoftheproposedalignmentofthefreewayandLRTtunnels,aswellasthecrosspassagesassociatedwith

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thesetunnels.ThefindingsofthisTMhavebeenusedinthedevelopmentofthepreliminarydesignevaluationsfortheboredtunnelandcrosspassageexcavationandsupport.

ThisTMdescribestheresultsofevaluationsperformedtocharacterizegroundconditionsforthetunnelalternatives,includingthedeterminationoftunnelreaches(TRs),andidentificationofgroundclasses(GCs).Groundcharacterizationinvolvesevaluatingavailablegeologicdata,assessingsoil/rockmassproperties,identifyingdistinctRockMassTypes(RMTs),estimatinganticipatedgroundbehaviorsalongtheproposedtunnelalignments,anddevelopinggeotechnicalparametersforpreliminarydesignevaluations.DeterminationofTRsinvolvesdividingeachofthetunnelalignmentsintoanumberofreachesofsimilarconditionsbasedontheanticipatedgroundconditionsandpotentialgroundbehavior.RMTsaredeterminedbasedonthelithology,fracturefrequencyandcondition,weathering,andstrengthoftherockformations.TheidentificationofgroundclassesinvolvesgroupingtheRMTsintoseveralGCsbasedonsimilargroundbehaviorsanticipatedduringtunnelexcavation.Itisassumedthattherunningtunnelsforeachalternativeareexcavatedwithpressurizedfacetunnelboringmachines(TBMs).ExcavationandinitialsupportofthecrosspassagesareanticipatedtobeconstructedusingtheSequentialExcavationMethod(SEM).

1.3 Purpose ThepurposeofthisTMistodocumentpreliminarydesignevaluationsandconceptsdevelopedinsupportoftheenvironmentaldocumentationfortheSR710NorthStudy.Theseconceptsalsoserveasabasisforpreliminaryconstructioncostestimate,developedforthetunnelsections.

ThepreliminarydesignconceptspresentedinthisTMwillbeconsideredinsubsequentenvironmentalstudies,andinmanycasesrepresentonefeasibleorlikelyoption.Otheroptionsshouldbeexplored,andtheconceptsshouldbetakentoafurtherlevelofrefinement,infuturephasesofthisstudyifeitheroftheboredtunnelalternativesiscarriedfurther.

2 Geologic Conditions TheprojectareaencompassesportionsoftheSanGabrielValley,thesouthernSanRafaelHills,theElysianHills,andtheRepettoHills(CH2MHILL,2014).TheRepettoHillsandSanRafaelHillsinthewesternpartoftheprojectareaarecharacterizedbysmallandmediumsizedroundedhillsandinterveningvalleys.TheSanGabrielValley,whichencompassestheeasternpartoftheprojectarea,isessentiallyaflat,gentlysouthslopingsurface.AmajorgeomorphicfeatureisArroyoSeco,whichisasteepwalled,flatflooredravineabout600to1,000feetwideand50feetdeep.TheprojectareaisprincipallyunderlainbyQuaternaryagealluvium,Tertiaryagesedimentaryrocks,andMesozoicagecrystallineigneousandmetamorphicrocks.Thesedimentaryrocksintheprojectareaconsistofclaystone,siltstone,mudstone,sandstone,conglomerate,andbreccia.

2.1 Sources of Geologic Data ThePreliminaryGeotechnicalReportfortheSR710NorthStudy(CH2MHILL,2014)wasreviewedandusedforthedevelopmentofthistechnicalmemorandum.Someadditionalinformationfrompreviousstudies(CH2MHILL,2010)werealsousedasareference.

2.2 Primary Geologic Units ThegeologicunitsalongtheproposedalignmentsfortheFreewayTunnelandLRTAlternativesareshowninFigure1andFigure2,respectively.Thesegeologicunits/formationsincludebothsoftgroundandrockformationsconsistingofartificialfill,alluvium,FernandoFormation,PuenteFormation,TopangaFormation,andbasementcomplexrocks(WilsonQuartzDiorite).TermsanddefinitionsusedtodescribethecharacteristicsoftherockformationsarepresentedinTables1through5.

ArtificialFill.Alongthetunnelalignments,artificialfillrangingapproximatelyfrom0to40feetthickoverliesthealluviumatthesouthernendofthealignments.TheboredtunnelsoftheFreewayTunnelandLRTAlternativesarelocatedgenerallybelowthefill.Thefillconsistsofheterogeneousmixturesofgravel,sand,silt,andclay,withvariableamountsofdebris.StandardPenetrationTest(SPT)Nvaluesare8and11basedontwotestsfromBoringRC13005.BlowcountsperfootusingStandardCaliforniasamplerare15and26basedontwotestsfromthesameboring.Table6summarizesthelaboratorytestresultsofundrainedshearstrengthandtheplasticityand


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liquidityindicesforthefinegrainedsoilsofthefill.Basedontheresultsofthetriaxialtests,theconsistencyofthefinegrainedsoilsisstifftohard.

Alluvium.Thealluviumdepositsconsistofinterbeddedlensesand/ordiscontinuouslayersoffinegrainedsoils(clayandsilt)andcoarsegrainedmaterials(sandandgravel)thatincludeawiderangeofsoiltypes.Forexample,alluvialsoilsretrievedfromtheboringsincludeGP,GW,SP,SW,SM,SWSM,SMSC,ML,MH,CLML,CL,andCH,asclassifiedbasedonUnifiedSoilClassificationSystem(USCS).Hardtoveryhardcobblesizerockclastsarecommonlocallywithinthealluvium,andsomehardtoveryhardbouldersmaybescatteredlocallythroughouttheunit.Table6summarizesthelaboratorytestresultsofundrainedshearstrength,plasticityindex,andliquidlimitforthefinegrainedsoilsofthealluviumdeposits.Triaxialtestsindicateundrainedshearstrengthintherangeof1.2to6.7ksfforthefinegrainedsoils.HistogramssummarizingtheSPTNvaluesofthealluviumwithinthetunnelzone(i.e.,betweenonetunneldiameterabovethetunnelcrownandonetunneldiameterbelowthetunnelinvert)areshowninFigure3.TheSPTNvaluesrangefrom0to50blowsfor1/2inchfortheFreewayTunnelAlternative,andfrom9to200blowsfor11inchesfortheLRTAlternative.Theseresultsgenerallyindicatethefinegrainedsoilsarestifftohard,andthecoarsegrainedsoilsareveryloosetoverydense.Someoftheboringlogsnotedrockfragments,gravels,and/orcobblesfortheSPTrefusals.LaboratorytestresultsforgrainsizedistributionareshowninFigure4forthealluviumtobeencounteredalongboththeFreewayandLRTalternativealignments.

FernandoFormation.AlongtheFreewayTunnelandLRTAlternatives,thePlioceneageFernandoFormationconsistsprimarilyofweak,massive,marineclaystone,andsiltstone.Scattered,hardconcretionsandverythintothinhardlayers,occurwithintheFernandoFormationSiltstoneMember.Figure5showscorephotographsofthemoderatelytoslightlyweatheredFernandoFormationtakenfromtheexplorationprogram.Averageshearwavevelocitymeasuredinthisformationrangesfrom880to2,800feetpersecond.ResultsoflaboratorytestingaresummarizedinTable7fortheFernandoFormation.TheFernandoFormationexhibitsanunconfinedcompressivestrength(UCS)intherangeofapproximately50to500psi.TheRQDvaluesrangesfrom0to100.Therockmassisgenerallyslightlytoveryslightlyfractured(i.e.,fracturespacingbetween1and10feet).LaboratorytestresultsforgrainsizedistributionoftheFernandoFormationareshowninFigure6.

PuenteFormation.ThemarinerocksofthelateMiocenePuenteFormationexpectedtobeencounteredalongthetunnelalignmentsconsistspredominantlyofthesiltstoneunit.Thisunitisathinlybeddedtolaminatedsiltstoneswithmediumtothickinterbedstolaminationsoffinegrainedsandstone.Therocksgenerallyareweakwithlocallystronglycementedinterbedsandconcretions.Theobservedcementedzonesandconcretionsweregenerallystrongandcanbehardtoveryhard.Figure7showscorephotographsofthemoderatelytoslightlyweatheredPuenteFormationtakenfromtheexplorationprogram.Averageshearwavevelocitymeasuredinthisformationrangesfrom900to3,360feetpersecond.ResultsoflaboratorytestingaresummarizedinTable7forthePuenteFormation.ThePuenteFormationexhibitsanunconfinedcompressivestrength(UCS)intherangeofapproximately40to500psi.TheRQDvaluesrangesfrom0to100.Therockmassisgenerallyintenselyfracturedtoveryslightlyfractured(i.e.,fracturespacingbetween1inchand10feet).LaboratorytestresultsforgrainsizedistributionareshowninFigure8forthesiltstonememberofthePuenteFormation.

TopangaFormation.ThemiddleMioceneageTopangaFormationincludesawidevarietyofrocktypesrangingfromcoarsegrainedrockssuchasbreccia,conglomerate,andsandstonetofinegrainedsandstoneandsiltstonewithminorclaystone.TheformationconsistspredominantlyofthesiltstoneunitsouthoftheRaymondfault.Thisunitconsistsofthinlybeddedtolaminatedandfissilesiltstonesandshales,withfinetocoarsegrainedsandstoneinterbeds.Localized,stronglycementedlayersand/orconcretionswereencounteredthroughtheformation.Thecementedzones,layersandconcretionsaregenerallystrongandcanbehardtoveryhard.Figure9showsphotosofthecoresofmoderatelytoslightlyweatheredTopangaFormationfromtheexplorationprogram.Averageshearwavevelocitymeasuredinthisformationrangesfrom1,170to5,400feetpersecond.ResultsoflaboratorytestingaresummarizedinTable7fortheTopangaFormation.TheTopangaFormationexhibitsanunconfinedcompressivestrength(UCS)intherangeofapproximately10to5,000psi.TheRQDvaluesrangesfrom7to100.Therockmassisgenerallyintenselyfracturedtoveryslightlyfractured(i.e.,fracturespacingbetween1inchand10feet).LaboratorytestresultsforgrainsizedistributionareshowninFigure10forthesiltstoneandconglomeratemembersoftheTopangaFormation.


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BasementComplexRocks.BasementComplexRocksintheprojectareaincludeseveraltypesofigneousandmetamorphicrockssuchas:diorite,monzonite,quartzdiorite,quartzmonzonite,andgneissicdiorite.Therockmineralogyisprimarilyplagioclasefeldsparswithquartz,hornblende,andbiotite.Figure11showsexamplesofBasementComplexRocksinamoderatelytoslightlyweatheredstate.Averageshearwavevelocitymeasuredinthisformationrangesfrom1,450to6,700feetpersecond.ResultsoflaboratorytestingaresummarizedinTable7.TheBasementComplexRocksexhibitsanunconfinedcompressivestrength(UCS)intherangeofapproximately35to1,600psi.TheRQDvaluesrangesfrom0to76.Therockmassisgenerallyintenselyfracturedtoveryslightlyfractured(i.e.,fracturespacingbetween1inchand10feet).

Histogramssummarizingthelaboratoryresultsofunconfinedcompressivestrength(UCS)andpointloadindex(PLI)testsforthevariousrockformationsareshowninFigures12and13,respectively.ItshouldbenotedtherearelimitednumbersofUCSandPLItests.SignificantlymoreUCSandPLItests,aswellasothertestsingeneral,arerequiredtoobtainarepresentativedistributionofrockstrengthandothergeotechnicalparametersforeachoftherockformations.

HistogramssummarizingtheRockQualityDesignation(RQD)valuesoftherockswithinthetunnelzoneareshowninFigures14and15forthefreewayandLRTtunnels,respectively.Itshouldbenotedthatthesehistogramswerepreparedbasedonthelimitednumberofboringsandtestsavailablealongthetunnelalignmentswithinthetunnelzone;therefore,thedistributionsshowninthesehistogramsmaychangeasadditionaldatabecomesavailable.ItisalsonotedthatRQDvaluesfromtheboringsarebasedonintactcorepiecesobtainedbetweennaturaldiscontinuities.However,duetotherelativelyweaknatureoftherockformations,asignificantportionofthecoresincludedintheRQDcalculationdonotnecessarilymeetthesoundcoredefinitionprovidedinthestandardtestmethodforRQD(ASTMD6032),soitcouldbeunconservativetousetheseRQDvaluestoevaluatetheoverallrockmassquality.ThisneedstobetakenintoconsiderationwhenreviewingtheRQDhistograms.FurthergeotechnicalinvestigationsinthefuturephasesofthisstudyarenecessarytobetterunderstandthecorrelationbetweentheRQDvaluesandtheanticipatedrockmassquality.

2.3 Geologic Structure AccordingtothePreliminaryGeotechnicalReport(CH2MHILL,2014),thegeologicstrataalongthetunnelalignmentsisdeformedintoseriesoffoldsandfaults.ThesefoldsandfaultsarearesultofongoingregionaltectonicforceswhicharepresentintheSR710NorthStudyAreaandtheLosAngelesBasin.SouthoftheRaymondfault,thesestructuresgenerallytrendsoutheasterlythroughtheRepettoHillsandcontinuebelowtheflatlyingQuaternaryalluviumoftheSanGabrielValleyinthevicinityofthetunnels.ThesefoldsincludetheElysianParkAnticlineandtheSouthPasadenaAnticline.FrequentchangesinbeddingorientationduetofoldingandfaultingareexpectedatthedepthsoftheFreewayandLRTtunnels.ManyofthefaultsmappedintheSR710NorthStudyAreaareinactiveandintraformationalfeatures(meaningthefaultsoffsetrocksofthesamegeologicformation).However,someoftheseinactivefaultsjuxtaposerocksofdifferentformationsaswell.Ineithercase,thewidthofthesefaultsalongthetunnelalignmentsisexpectedtovarywidely,includingnarrowtowidezonesofhighlyfracturedrockand/orclayeygouge.

SeveralfaultsareshownonthegeologicprofilesinFigure1andFigure2.AccordingtothePreliminaryGeotechnicalReport(CH2MHILL,2014),Raymondfaultisidentifiedasanactivefault,andtheSanRafaelandEagleRockfaultsareidentifiedaspotentiallyactivefaults.TheotherfaultsshowninFigures1and2areconsideredinactivefaults.Onlyafewoftheboringsactuallypenetratedthroughthefaultzones;therefore,limitedinformationisavailableonthegeotechnicalconditions,andexactwidthsandlocationsofthefaultzones.However,thehorizontalzoneofuncertaintyforthelocationofeachactiveandpotentiallyfaulthasbeenestimatedinthepreliminaryfaultinvestigationconductedfortheSR710NorthStudy(CH2MHILL,2014).Acombinedzoneofuncertaintyofabout240feetisestimatedforthethreeRaymondfaultstrandsanticipatedatthefreewayandLRTtunneldepths.Thetunnelscouldintersectadditionalfaultstrandsforanadditional200feetnorthofthemainfaultzone,butitisunlikelythatthezoneofactivefaultingwouldextendthatfarnorth.TheSanRafaelfaultzoneoccursonthenorthsideofRaymondHillandseparatesbasementcomplexrocksfromtheTopangaFormation.Thefaultzoneismappedashavingamainstrandandtwopotentialsecondarystrands.Thehorizontalzoneofuncertaintyforeachofthefaultstrandsrangesfrom75to120feetand100to260feetatthefreewayandLRTtunneldepths,respectively.TheEagleRockfaultislocatedapproximately2,000feetsouthofthe


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SanRafaelfault.ThefaultwouldnotcrosstheLRTtunnelalignmentbasedoninterpretationdiscussedinthePreliminaryGeotechnicalReport(CH2MHILL,2014).Ahorizontalzoneofuncertaintyapproximately85feetwideisestimatedfortheEagleRockfaultatFreewaytunneldepth.Additionalgeotechnicalinvestigationswouldberequiredtofurtherrefinethelocationsandwidthsofthefaultzones.RefertotheFaultRuptureEvaluationandpreliminaryfaultinvestigationfortheSR710NorthStudy(AppendicesEandGinCH2MHILL,2014)foradditionaldetailsandestimatesofearthquakemagnitude,andfaultrupturedisplacementandwidth.

2.4 Groundwater and Rock Mass Permeability TheestimatedgroundwaterlevelsalongthefreewayandLRTtunnelsareshowninFigure1andFigure2,respectively.Thedepthtogroundwaterrangesfromlessthan10feettoapproximately175feetbelowgroundsurfacealongthefreewaytunnelalignment,resultingingroundwaterlevelsuptoapproximately150feetabovetheFreewaytunnelcrown.FortheLRTalignment,thedepthtogroundwaterrangesfromlessthan10feettoapproximately160feetbelowgroundsurface,resultingingroundwaterlevelsuptoapproximately70feetabovethetunnelcrown.ThereappearstobeasignigicantdifferenceingroundwaterlevelsoneithersideoftheRaymondFault,sugguestingitmaybeagroundwaterbarrier.

TheunconsolidatedalluvialsedimentsoftheSanGabrielValleyandtheRaymondBasinsconstituteimportantgroundwaterbasinsinSouthernCalifornia.Thegroundwaterbasinsmainlyincludethesandandgraveldepositsandhavebeenactivelyexploitedbylocalcommunitiesforthelastfewdecadesasasourceofgroundwater.Thesedeepaquifersareoverlainlocallybyperchedgroundwaterbodies.Basedonthemapofgroundwaterbasinsintheprojectarea(CH2MHILL,2014),boththefreewayandLRTtunnelalignmentstraversethroughthegroundwaterbasinswheretunnelexcavationsareexpectedtoencounteralluvialsoilsbelowthegroundwatertable.

Thesedimentaryandbasementcomplexrockmassescontainwater;however,forthepurposesofwatersupply,theseunitsaregenerallyconsideredtobenonwaterbearing.Theestimatedrangesofpermeabilityforeachbedrockunit,basedonresultsoftheavailablepackertestdata,aresummarizedinTable8.

Forthetunnelreachesbelowthegroundwatertable,groundwaterisexpectedtohaveasignificantimpactoninflows,tunnelstability,andgroundmovementsduringconstruction.Theselectedtunnelexcavationandsupportmethodsneedtoaddressandmitigatethepotentialimpact.RefertoTunnelExcavationMethodsTM(JA,2014)forhowthegroundwaterrelatedissuescanbeaddressedduringconstruction.

2.5 Potentially Gassy Conditions AccordingtothePreliminaryGeotechnicalReport(CH2MHILL,2014)thereisalowtomoderatepotentialofencounteringnaturallyoccurringoiland/orgas,mostlikelywithinthatPuenteFormation,alongthesubterraneanportionsoftheFreewayTunnelandLRTAlternatives.Naturallyoccurringoiland/orgascouldalsobefoundwithinanyofthegeologicformationswithinthestudyarea.Nooilwellsarelocatedintheimmediatevicinityofthetunneledalternatives;therearenearbyoilwells,butthenumberanddensityofthewellsaresuchthattheyarenotexpectedtohaveaneffectontunneledalternatives(CH2MHILL,2014).

3 Characterization of Geologic Units Thecharacterizationofgeologicunitsinvolvestwotasks:identifyingandcharacterizingsoildeposits(SDs)androckmasstypes(RMTs)withsimilarmechanicalcharacteristics,andestimatingparametersassociatedwitheachSDandRMTfortunneldesignevaluation.TheinformationderivedfromthecharacterizationofgeologicunitsisusedinSection4ofthisTMforidentifyinggroundbehaviorsassociatedwitheachSDandRMT.GroundclassesarethendefinedbasedontheanticipatedgroundbehaviorsassociatedwitheachSDandRMT.Forcrosspassagedesignpurposes,theinformationofanticipatedgroundclasseswillbeusedforselectionofexcavationandsupportmethods.

ThecharacterizationofgeologicunitsisbasedonanevaluationoftheavailablegeotechnicaldataasdescribedinSection2.1.TheidentificationofSDsandRMTsdependsonthegeologiccharacteristicsandrelevantgeotechnicalparametersalongthetunnelalignment,asobservedintheboreholesandotherinvestigations.SDsarecharacterizedbasedonsoilclassificationintermsofthegrainsizedistributionandAtterberglimits,aswellasengineeringpropertiesincludingrelativedensityorconsistency,andundrainedshearstrength.Incharacterizing


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theRMTs,theGeologicalStrengthIndex(GSI)system(HoekandBrown,1974)andthemodifiedTerzaghisrockmassclassificationsystem(ProctorandWhite,1968;Deere,etal.,1969)areemployedtoclassifytherockmassconditionsforeachoftheRMTsdefined.Incharacterizingtherocks,thesesystemstakeintoaccountoftherocksstructuralconditionssuchasdiscontinuityspacingandblockiness,andfortheGSIsystem,surfaceconditionsofthediscontinuitiesincludingroughnessandweatheringconditionarealsoconsidered.Astherockformationsencounteredareprimarilystratifiedandtendtoformslabsratherthanblocks.Theirbehaviorisexpectedtobecontrolledlargelybythebeddingplaneweaknessandpartings.TheterminologyusedinthismemosuchasblockyorseamywhenreferringtothemodifiedTerzaghisrockmassclassificationsystemshouldbeassociatedwiththerockstructuresofbothslabsandblocks.

ItisalsonotedthattherockmassqualityassessmentsandgroundcharacterizationcanalsobecarriedoutusingtheRockMassRating(RMR)(Bieniawski,1989)andQ(Bartonetal.,1974)rockmassclassificationsystems.Thesesystemsmaybeemployedinthefuturephasesofthisstudytoenhancetheunderstandingofrockmasscharacteristicsandassociatedgroundbehaviorduringthetunnelexcavations.

3.1 Soil Deposits Thealluvium,whichoverliesthebedrock,rangesfromapproximately0to280feetinthicknessalongtheFreewayTunnelalignment.BasedonFigure1,approximately20percentand10percentofthelengthofthetunnelexcavationisexpectedtoencounteralluvialsoilsandmixedfaceconditions(i.e.,alluvialsoilsoverbedrock),respectively.

Thealluviumrangesfromapproximately0to300feetinfeetthicknessalongtheLRTalignment.BasedonFigure2,approximately45percentand25percentofthelengthofthetunnelexcavationisexpectedtoencounteralluvialsoildepositsandmixedfaceconditions,respectively.

Thealluvialsoilsgenerallyincreaseinstrengthwithdepth.TheconsistencyofthefinegrainedsoilencounteredintheboringswithintheFreewayandLRTtunnelzonestypicallyrangedfromstifftohard;whiletherelativedensityofthecoarsegrainedmaterialsencounteredrangedfromveryloosetoverydense,butaretypicallydensetoverydense.Althoughadetailedstudyofthecharacteristicsoftheboulderswithinthealluviumhasnotbeenperformedspecificallyforthisprojectatthecurrentdesignstage,informationfrompastlocaltunnelingprojectsprovideanindicationonthesizeandstrengthofbouldersthatmaybeencounteredduringtunneling.Themaximumdimension(i.e.,size)ofstrongtoextremelystrongboulders(seeTable1)isprobablyabout3to5feetbasedondescriptionsingeotechnicalbaselinereports(GBRs)fromlocaltunnelingprojectsthatincludetheRegionalConnectorTransitCorridor(TheConnectorPartnership,2012),EastsideLRT(EastsideLRTPartners,2002),andNortheastInterceptorSewer(NEIS)projects(LADPW,2001).Onavolumebasis,theamountofcobblesandbouldersbaselinedinthesepastreportsrangesfromsignificantlylessthanonepercenttoafewpercentofmaterialsthatmakeupthealluvium.Thecharacteristicsofthecobblesandbouldersshouldbeevaluatedfurtherinfuturedesignphasesasadditionaldatabecomesavailable.

Basedonthegeotechnicalinformationreviewed,lowerbound(LB)andmeanengineeringpropertiesofthealluviumrecommendedfortunneldesignaresummarizedinTable9.

3.2 Rock Formations AsdiscussedinSection2,fourrockformationsareexpectedtobeencounteredalongthetunnelalignments.Duetolargevariationsinrockmassquality,eachoftherockformationsexhibitsquitedifferentcharacteristics,whichmayresultinsignificantlydifferentgroundbehaviorsduringtunnelexcavation.Thesedifferentgroundbehaviorsusuallyrequiredifferentexcavationandsupportmeasurestostabilizetherockmass,providesafeconditions,andachieveacceptablelongtermperformanceduringtunneloperations.Theobjectivesofthegroundcharacterizationprocessaretoidentifyandgrouptogetherrockmassconditionswithsimilarcharacteristicsandexpectedbehaviors.Thisfacilitatesbothdesignandconstructionsosimilarexcavationandsupportmeasurescanbedevelopedtohandletherangeofanticipatedgroundconditionsassociatedwitheachgroup.

Incharacterizingtherockmass,eachofthefourrockformationswascharacterizedandsubdivided,whenpertinent,intoRMTsonthebasisofrockmassqualityintermsofdiscontinuityspacingandcondition,strength,andweathering.EngineeringpropertiesincludingstrengthanddeformationmoduliwerethendevelopedforeachoftheRMTsforevaluationofanticipatedgroundbehavioranddesignoftunnelexcavationandsupportmethods.


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PotentialgroundbehaviorassociatedwiththetunnelexcavationineachRMTwasevaluatedusingapplicablegeomechanicalpropertiesandgroundandexcavationconditionssuchasinsitustresses,groundwaterconditions,excavationdimensions/orientationsandsequence,andinitialsupportmeasures.Itshouldalsobenotedwhilethesiltstone/claystonemembersoftheFernando,PuenteandTopangaformationsareindicatedaspotentiallyexpansive(CH2MHILL,2014),thetunnelalignmentswithintheseformationsaregenerallyanticipatedtobebelowthegroundwaterlevelsuchthatthegroundmaynotexhibitsignificantswellingbehaviorduringtunnelexcavation.Additionally,basedonpastlocaltunnelexperienceincludingNEIS,thePuenteFormationwasnotclassifiedasswellinggroundforthepurposeofbehaviorduringtunnelexcavation.Additionaltestingfromfuturegeotechnicalinvestigationsshouldbeperformedtoverifyiftheformationhasanyswellingpotentialandhowitmayaffecttunnelexcavation.Asummaryoftherockmasstypesandtheirassociatedkeycharacteristicsispresentedbelow.

3.2.1RockMassTypes.Rockmasstypes(RMTs)representrockmassconditionswithsimilarlithology,physicalcharacteristics,and/ormechanicalproperties.RMTsarethebasisforthedefinitionofrockmasscharacteristicsforfieldidentificationduringconstruction.Theyalsoprovidethebasisfordevelopingestimatesofmaterialspropertiesforpreliminarydesignevaluations,aswellasforidentifyinggroundclassesalongthetunnelalignmentfordeterminationofexcavationandsupportrequirements.

Thedefinitionsintermsofintactrockstrength,fractureandbeddingspacing,rockweathering,andslakedurabilityareprovidedinTables1to5,respectively.

FernandoFormation(RMTTf)

FernandoFormationisafairlyuniform,weakrockformationanditcanbedescribedbyasingleRMT,definedhereinasRMTTf.Therockmassismassive,slightlytoveryslightlyfractured,moderatelytoslightlyweathered,andextremelyweaktoveryweak.ThisformationisconsideredtobeonorderbetweenhardsoilandveryweakrockandischaracterizedhereinasMassive,ModeratelyJointedtoVeryBlockyandSeamyintermsofthemodifiedTerzaghisrockmassclassifications(Deereetal.,1969).

Intermsoftheoverstressratio(definedastheratioofrockstrengthtoinsitustress),theFernandoFormationatthedepthoftheFreewayTunnelAlternativehasavaluerangingfrom0.3to1.6,indicatingthattherockhasMinortoSmallsqueezingpotential(Hoek,2000).

PuenteFormation(RMTsTp1andTp2)

Fortunneldesignpurposes,thePuenteFormationischaracterizedbytwoRMTs,Tp1andTp2.Tp1rockmassisverythicklybeddedtomassive,slightlytoveryslightlyfractured,moderatelyweatheredtofresh,andweaktostrong.TheGSIforTp1isestimatedtorangefrom45to55.RMTTp2isverythinlytomoderatelybedded,moderatelytointenselyfractured,moderatelyweathered,andextremelyweaktoveryweak.TheGSIforTp2isestimatedtorangefrom35to45.Stronglycementedlayersand/orconcretionsareexpectedtobelocallywithinTp1andTp2.IntermsofthemodifiedTerzaghisrockmassclassifications,RMTTp1ischaracterizedhereinasMassive,ModeratelyJointedtoModeratelyBlockyandSeamy,andRMTTp2ischaracterizedhereinasVeryBlockyandSeamy.IntermsoftheGSIsystemRMTTp1andRMTTp2arecharacterizedhereinasMassivetoBlockyandVeryBlockytoBlockyandSeamy,respectively.

TopangaFormation(RMTsTt1andTt2)

Fortunneldesignpurposes,theTopangaFormationischaracterizedbytwoRMTs,Tt1andTt2.Tt1rockmassisthinlytothicklybedded,slightlytoveryslightlyfractured,moderatelyweatheredtofresh,andweaktomediumstrong.TheGSIforTt1isestimatedtorangefrom50to60.Tt2rockmassisthinlytomoderatelybedded,moderatelytointenselyfractured,moderatelyweathered,andextremelyweaktoveryweak.TheGSIforTt2isestimatedtorangefrom40to50.Stronglycementedlayersand/orconcretionsareexpectedtobelocallywithinTt1andTt2.IntermsofthemodifiedTerzaghisrockmassclassifications,RMTTt1ischaracterizedhereinasMassive,ModeratelyJointedtoModeratelyBlockyandSeamy,andRMTTt2ischaracterizedhereinasVeryBlockyandSeamy.IntermsoftheGSIsystem,RMTTt1andRMTTt2arecharacterizedhereinasMassivetoBlockyandVeryBlocktoBlockyandSeamy,respectively.


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BasementComplexRocks(RMTsWqd1andWqd2)

Fortunneldesignpurposes,theBasementComplexRocksarecharacterizedbytwoRMTs,Wqd1andWqd2.Wqd1rockmassisofslightlytoveryslightlyfractured,moderatelyweatheredtofresh,andweaktomediumstrong.TheGSIforWqd1isestimatedtorangefrom50to60.Wqd2rockmassismoderatelytointenselyfractured,moderatelyweathered,andextremelyweaktoveryweak.TheGSIforWqd2isestimatedtorangefrom30to45.IntermsofthemodifiedTerzaghisrockmassclassifications,RMTWqd1ischaracterizedhereinasMassive,ModeratelyJointedtoModeratelyBlockyandSeamy,andRMTWqd2ischaracterizedhereinasVeryBlockyandSeamytoCompletelyCrushed.IntermsoftheGSIsystemRMTWqd1andRMTWqd2arecharacterizedhereinasMassivetoBlockyandVeryBlockytoDisintegrated,respectively.

3.2.2RockMassParameters.Overallrockmassparametersarecontrolledbythepropertiesoftheintactrockpieces,thepresenceofdiscontinuities(i.e.bedding,jointsandshears)andthefreedomofthesepiecestoslideandrotateunderdifferentstressconditions(Hoeketal.,1995).Inadditiontotheeffectduetodiscontinuitieswithintherockmass,behaviorsofrelativelyweakrocks,suchasthoseoftheFernando,PuenteandTopangaFormationsarecontrolledbythelowstrengthoftherockmaterials.Rockmasspropertiesalsodependonscale;thevolumeofrockwithinonediameterofthetunnelexcavationwilllargelycontrolthebehaviorofthetunnelopening(Marinosetal.,2005).ParametersintermsofstrengthandstiffnesspropertiesassociatedwitheachoftheRMTsareestimatedanddiscussedbelow.Theseparameterswillbeusedforthepreliminarytunneldesignevaluationandanalysisandmaybereassessedandupdatedinthefuturephasesoftheproject.

Strengthproperties

SinceitisnotpossibletotesttherockmasswithrepresentativegeologicfeaturesatthescaleorsizeofthetunnelforthevariousRMTs,rockmassstrengthisestimatedusingacombinationofgeologiccharacterization,laboratorytesting,andempiricalmethods.Geologiccharacterizationisbasedonobservationofcores,corelogs,andcorephotographs.Testresultsusedintheassessmentofrockmassstrengthparametersincludeuniaxialandtriaxialcompressiontestsandfieldpointloadtests.Figures13and14showhistogramsoftheUCSandPointLoadIndex(PLI)values,respectively,forthevariousrockformations.

TheGeologicalStrengthIndex(GSI)system(Hoeketal.,2002),whichempiricallycombinesqualitativeengineeringgeologyassessmentsandlaboratorytestresults,wasusedtoestimaterockmassstrengthforthePuenteFormation,TopangaFormation,andBasementComplexRocks.Thesysteminvolvesthefollowingparameters:GSIratings;UCSofintactrock;HoekBrownparameter,mi(HoekandBrown,1997);anddisturbancefactor,D.TherockmassstrengthfortheFernandoFormationwasestimatedbasedonlaboratorytestresultsandexperiencesfromlocalrelevantprojects,suchastheNortheastInterceptorSewer(NEIS)Project.

EvaluationoftheGSIclassificationparameterswasperformedoncoreintervalsofabout20to60feet,whichrepresenttherangeoftunnelexcavationsizesforboredrunningtunnelsandcrosspassagesforbothFreewaytunnelandLRTalternatives.Rockmasscharacteristicsatthisscaleareexpectedtocontroloveralltunnelbehaviorandcorrespondingsupportrequirements.GSIratingsarebasedonqualitativeidentificationoftheappropriaterockmassstructureanddiscontinuitystrengthfromGSIchart(seeFigure16).EvaluationsofmiandDwerebasedonrecommendedvaluesbyHoeketal.(1995)andHoekandDiederichs(2006),respectively.Adisturbancefactor(D)ofzerowasassignedgloballyfortheevaluationofrockmassstrengthsincetheexcavationinduceddisturbanceislikelytobeminimaliftheboredrunningtunnelsareexcavatedusingaTBM,whilecrosspassageswouldbeexcavatedusingaroadheaderorexcavator.MeanandlowerboundvaluesoftheHoekBrownenvelopeparameters(GSI,UCS,mi)wereestimatedforeachoftheRMTs.Table10summarizesthepreliminaryrockmassstrengthestimatedforeachoftheRMTs.Correspondingequivalentstrengthpropertiesshowninthetable,includingcohesionandfrictionalangleforMohrCoulombyieldcriterion,wereestimatedbasedontheanticipatedrangeofconfiningstresslevelsatthedepth(averageabout50and150feet)oftunnelexcavations.TheapproachemployedforthisestimationispresentedinHoek(2007).

Deformationmodulus

Rockmassdeformabilityisalsoascaledependentproperty.Similartothestrengthproperties,thedeformationmodulusalsoneedstobedeterminedatthescaleofthetunnel.Themostcommonmeasureofrockmassdeformabilityisthedeformationmodulus.Thedeformationmodulusistheunloading/reloadingmodulusofa


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virginloadcurvemeasuredinthefieldduringapressuremetertestorbackcalculatedfromgroundmovementsresultingfromanexcavation.Theunloading/reloadingdeformationmodulusrepresentstheresponseofrockmassfollowingthetunnelexcavationandsupportinstallation(anunloadingandreloadingprocess).Therefore,thismodulusisrecommendedfortunneldesignevaluation.

Estimatesofthedeformationmodulusinahighlyfracturedrockmasscanhavesignificantvariations(HoekandDiederichs,2006),buttheprobablerangeofthedeformationmodulusofarockmasscanbeestimated(RafaelandGoodman,1979).Forthisstudy,severalapproacheswereusedincombinationtoestimatetherangeofdeformability.Themethodsusedinclude:

Empiricalequations

Availabledownholeseismicvelocitydata

Fieldtestingresultsfrompressuremetertests

Theintactrockmodulusfromlaboratorytests

EmpiricalequationsusedtoestimatetherockmassmodulusarebasedonfieldmeasurementsofdeformationandincludetherelationshipsproposedbyHoeketal.(2002)andHoekandDiederichs(2006).Whereavailable,resultsfromdownholeshearwavevelocitymeasurementswereusedtoestimatethestaticrockmassmodulus.Thestaticrockmassmoduluswasestimatedfromtheshearwavevelocityusingaratiobetweenthestaticmodulusanddynamicmodulusof5forhighlyfracturedrock(RafaelandGoodman,1979).Whereavailable,fieldtestingresultsfrompressuremetertestingwerealsousedtoestimatethedeformationmodulus.Theintactrockmodulusfromlaboratorytestsistypicallyconsideredanupperboundlimitwhichthedeformationmodulusoftherockmassshouldnotexceed.Table10summarizesthemeanandlowerboundmoduliofdeformationandPoissonsratioforeachRMT.Thesepreliminaryparametersarebasedontheevaluationsofavailablegeotechnicaldatausingthemethodslistedaboveandexperiencewithsimilarrock.Table11providesacomparisonofestimateddeformationmodulifromdifferentapproachesforeachoftheRMTs.

3.3 In Situ Stresses Theratiosofinsituhorizontalstresstoverticalstress(K0)inbedrockhavebeenestimatedbasedontheresultsofanumberofpressuremeterteststhathavebeencompletedfortheproject.TheinsituhorizontalstressesareassumedtobetheinitiallateralstressesindicatedinthepressuremetertestreportscontainedinthePreliminaryGeotechnicalReport(CH2MHILL,2014).Theeffectivehorizontalstresswascalculatedbysubtractingtheestimatedhydrostaticpressuresbasedonthewaterlevelindicatedontheboringlogs.K0valuewasthenestimatedbasedonthecalculatedeffectivehorizontalstressandtheeffectiveverticalstressatthedepthofthepressuremetertest.

BasedonthecalculatedK0valuefrompressuremetertestsandpastexperiencesfromlocalprojectsincludingtheRegionalConnectorTransitCorridorproject,theK0valuesforsedimentaryrockformationsareestimatedtorangefromapproximately0.5to1.35attunneldepths.TheK0valueforthebasementcomplexrocksisestimatedtobeabout0.5basedonlimitednumberofpressuremetertests.ItshouldbenotedthatestimationoftheK0valuesinvolvedsignificantuncertaintiessuchasthedegreeofdisturbancestotheboreholewallscausedbydrilling,amountofstressreliefinthegroundpriortopressuremetertesting,andtheaccuracyofthemodelusedtocalculatetheinitiallateralstressbasedonpressuremetertestingdata.

Tables9and10providetherecommendedK0valuesforthepurposesofpreliminarydesignevaluationforthesoilunitsandthevariousrockformations,respectively.Thesevaluesarefortypicalgroundconditions.Infaultzones,insitustressescouldbequitedifferentbecauseofthepasttectonicmovementsandvaryinggroundconditionsovershortdistanc

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SR 710 Tunnel Evaluation Report.pdf