Thedynamicshearmodulusratioanddampingratioofsandygravelareimportantparametersfortheseismicresponseanalysisofvalleygeomorphicsites,whichhaveanimportantimpactonthedeterminationofdesigngroundmotionparameters.Inthispaper,thedynamictriaxialtestofsandygravelshasbeenperformedbasedontheprojectoftheShangluoSeismicMicrozonation.Combinedwiththeotherresultsofsandygravel,therecommendedresultsofslightlydense,mediumdenseanddensesandygravelwereobtained.Bybuildingthetypicalsitemodel,theinfluenceofthedynamicshearmodulusratioandthedampingratiouncertaintyontheseismicresponseofthesiteisstudied.Theresultsshowthattheuncertaintyoftheaverageofthedynamicshearmodulusratioandthedampingratio±1timesthestandarddeviationhaslittleeffectonthepeakaccelerationofthesandygravelsite,andtherationalityofthegroupingandstatisticalresultsisexplained.Underdifferentprobabilitylevels,thechangeintheshearmodulusratioanddampingratioleadstoasignificantdifferenceinthehighfrequencyresponsespectrum.Theresponsespectrumof0.04-0.1srangesfromabout20%,butithaslittleeffectonthelongperiodspectrumofmorethan1.0s.Thestudyofdynamicshearmodulusratioanddampingratioofsandygravelhastheabilitytoimprovethereliabilityofthedesigninggroundmotionparameters.
