Evaluation of approaches to calculate debris-flow parameters碎屑流物质参数确定

流石流,碎屑流,参数

EngineeringGeology102(2008)152–163

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EngineeringGeology

journalhomepage:http://doc.xuehai.net/locate/enggeo

Evaluationofapproachestocalculatedebris- owparametersforhazardassessment

MarcelHürlimanna, ,DieterRickenmannb,c,VicenteMedinad,AllenBatemand

a

DepartmentofGeotechnicalEngineeringandGeosciences,TechnicalUniversityofCatalonia,JordiGirona1-3,08034Barcelona,SpainSwissFederalResearchInstituteWSL,MountainHydrologyandTorrents,Zürcherstrasse111,8903Birmensdorf,Switzerlandc

UniversityofNaturalResourcesandAppliedLifeSciences,DepartmentCivilEngineeringandNaturalHazards,InstituteofMountainRiskEngineering,PeterJordan-Strasse82,1190Vienna,Austriad

SedimentTransportResearchGroup,DepartmentofEngineeringHydraulic,MarineandEnvironmentalEngineering,TechnicalUniversityofCatalonia,JordiGirona1-3,08034Barcelona,Spain

b

articleinfoabstract

Manydifferentrunoutpredictionmethodscanbeappliedtoestimatethemobilityoffuturedebris owsduringhazardassessment.Thepresentarticlereviewstheempirical,analytical,simple owroutingandnumericaltechniques.Allthesetechniqueswereappliedtoback-calculateadebris ow,whichoccurredin1982atLaGuinguetacatchment,intheEasternPyrenees.Asensitivityanalysisofinputparameterswascarriedout,whilespecialattentionwaspaidtothein uenceofrheologicalparameters.WeusedtheVoellmy uidrheologyforouranalyticalandnumericalmodelling,sincethis owresistancelawcoincidedbestwith eldobservations.Thesimulationresultsindicatedthatthe“basal”frictioncoef cientsratheraffecttherunoutdistance,whilethe“turbulence”termsmainlyin uence owvelocity.Acomparisonofthevelocitycomputedonthefanshowedthattheanalyticalmodelcalculatedvaluessimilartothenumericalones.ThevaluesofourrheologicalparameterscalibratedatLaGuinguetaagreewithdataback-calculatedforotherdebris ows.Empiricalrelationshipsrepresentanothermethodtoestimatetotalrunoutdistance.Theresultscon rmedthattheycontainanimportantuncertaintyandtheyarestrictlyvalidonlyfortheconditions,whichwerethebasisfortheirdevelopment.Withregardstothesimple owroutingalgorithm,thismethodscouldsatisfactorilysimulatethetotalareaaffectedbythe1982debris ow,butitwasnotabletodirectlycalculatetotalrunoutdistanceandvelocity.Finally,asuggestiononhowdifferentrunoutpredictionmethodscanbeappliedtogeneratedebris- owhazardmapsispresented.Takingintoaccountthede nitionofhazardandintensity,thebestchoicewouldbetodividetheresultinghazardmapsintotwotypes:“ nalhazardmaps”and“preliminaryhazardmaps”.Onlytheuseofnumericalmodelsprovided nalhazardmaps,becausetheycouldincorporatedifferenteventmagnitudesandtheysuppliedoutput-valuesforintensitycalculation.Incontrast,empiricalrelationshipsand owroutingalgorithms,oracombinationofboth,couldbeappliedtocreatepreliminaryhazardmaps.Thepresentstudyonlyfocussedonrunoutpredictionmethods.Othernecessarytaskstocompletethehazardassessmentcanbelookedupinthe“Guidelinesforlandslidesusceptibility,hazardandriskzoning”includedinthisSpecialIssue.

©2008ElsevierB.V.Allrightsreserved.

Articlehistory:

Accepted4March2008

Availableonline19July2008Keywords:Debris owRunout

HazardassessmentPyrenees

1.Introduction

Besidestheprobabilityofoccurrenceandmagnitudeofafuturedebris ow,thedeterminationofitsdynamicsisoneofthemostimportanttasksduringhazardassessment(Jakob,2005;JTC1,2008-thisissue).Thetotalrunoutdistance,theareaaffectedbytheeventandtheenergyalongthe owpatharenecessaryinformationforhazardmappingandshouldbeideallydeterminedbyadynamicmethod.Theselectionoftheadequatemethodduringrunoutanalysis,however,isadif culttask.

Themethodsavailableforrunoutanalysiscanbedividedintodifferentclasses,suchasempirical,analytical,simple owroutingand

Correspondingauthor.Tel.:+34934017377;fax:+34934017251.E-mailaddress:marcel.hurlimann@upc.edu(M.

Hürlimann).0013-7952/$–seefrontmatter©2008ElsevierB.V.Allrightsreserved.doi:

10.1016/j.enggeo.2008.03.012

numericalones(Daietal.,2002;Hungretal.,2005;Rickenmann,2005a).Moreover,thesetechniquescanbeclassi edconcerningthedimensionofthecalculation.Hereinwemakeuseofthehydraulicde nitionandthetermone-dimensional(1D)forcalculationsalongapreviouslyselectedtopographicpro le.Incontrast,two-dimensional(2D)methodsdeterminedebris- owdynamicsoveranareatypicallyrepresentedbyadigitalelevationmodel(DEM).Thus,1Dmethodsmustbeextrapolatedintotwodimensionstoobtainahazardmap,while2Dtechniquescanbeusedtodirectlycreateahazardmap.

Thepresentpublicationcomplementsthearticleentitled“Guide-linesforlandslidesusceptibility,hazardandriskzoning”(JTC1,2008-thisissue).Ourreviewandevaluationofdifferentdebris- owrunoutandintensitycalculationmethodsonlydealswithonesingletaskduringhazardassessment.Themainobjectivewouldbethentohelptheexpertsinchargeofarunoutanalysistoselecttheappropriate

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