EXH0384021697

Easierfor me to writeitout,..] thinkthiscaptureseverything(I w_llnotincludethisin myfilesfor 3R inthe eventI haveforgottena steporsomething).,. Subgradeimprovementgovernedbyliquefaction.Ourreanalysisof triggerliquefactionshoweda reduced numberof sampleswouldliquefyusingthelower PGAvaluefromthe PSHA/ProShakeanalysis.The reducednumberof liquefiablesamplesresultedina lowerpost-liquefactionundrainedresidualshear strength(PLURSS). However,theextentof liquefactionin theNSAdidnotchangesignificantly(despite thereducednumberof liquefy}rigsamples).Thus, ourreanalyslsshoweda 120 footwidesubgrade Improvementzonewasneeded(thisgaveusa 1.2 factor-of-safetyforthe liquefactioncase). We decided atthe timethatthenest towidensubgradeimprovementswas predominantlydueto thechangein residualshearstrength,w_thsomecontributionfrom the changeto1.8H:1Vandclayto phi30. Afterour callwithBobMaruska,we wentbackand tooka closerlookat theeffectsof the claygoingto 30 dog, (wethoughtthismayhavecontributedenoughthatgoingbackto 32 dog.wasan acceptablewayto avoidwidentngsubgradeimprovementsperMaruska).We foundthishadnoreadeffecton FS. Takinga closerlookatsubgradeImprovementwidths,we determinedthat110was-areasonablerecommendation givena F$ of1.2 for120 ft anda 1.2for 100 ft, so wesentthe faxto HNTBshowingbothoptionsand leavingitto theirdecislorL Fortheareasouthof156thin NSA,we showeda 120 ft widesubgradeimprovementzoneinthefirstlax toHNTBbasedon theresultsof theliquefactioncase usingPLURSSfrom theseismicreanalysis,We thentooka closerlookatthe soilconditionsandliquefiableblowcountsandfoundthe compositestrength approachwasappropriateforthisarea basedondepthstratificationof liquefiableblowcounts. Forarea northof westwall,we initiallybasedourrecommendationof NO subgradeimprovementson our. compositeshearstrengthanalysis.Basedonboardcomments,welookedat PLURSSand relookedat extentof liquefactionfromCPT inputanddefineda discretezone. Foundthatsubgradeimprovements wereneeded.Locationof liquefiableso_andconstructabilityissuesledusto extendwestwallsubgrade improvementsnorththroughinterpretedextentof liquefaction.Tested a 100footwidesubgrade improvementzoneandJiquefactioncase>>1.1, steadystaterainwas1.45 andpseudostaticcase1,07, (_q_-_cD Nosubgradeimprovementsneededfrom_to 205+00for liquefactioncasebecausewe are comfortablewithcompositeshearstrength_.pproach. In general,pseudo-staticcasehasFS near 1.0 or 1.1 for toecJmularsurfacWs.Where subgrade Improvementsare locatedFS aregenerallynear 1.1. Areas wherenosubgradeimpr.are locatedFSsare near1.0. AR 021697 EXH0384021697

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PSCAA Advisory Council Meeting Agenda
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Call to order – Roll Call – Quorum Established – Land Acknowledgement We would like to acknowledge that our Agency operates in four present-day counties, which are the traditional lands of the Coast Salish people, past and present. This acknowledgement does not take the place of authentic relationships with indigenous communities in our jurisdiction and [...]