PRESENT TRENDS IN LANDSLIDING CONTROL I. Lungu, N. Boi, A.
Stanciu, O. Donciu ABSTRACT
Theefficientmanagementofthenaturaldisasterisabaseconceptforthelongterm
developmentofallsocieties.Oncethepresentproblemsrelatedtolandslidesaredefinedas
partofthenaturaldisasterissue,newapproachesandmethodsareneededthatwill
simultaneouslyallow:theimprovementofprognosisrelatedtotheplace,timeand
characteristicsofthesenaturalphenomena,creatingscenariosconcerningtheoptimum
strategiestoadoptwhensuchadisasteristriggered,aswellastheadoptionofpost-disaster
strategies in order to reduce the damages and re-install the
normality withinthecommunity.
Thepaperpresentselementsthatdefinesuchmethodsbasedongeo-sciencesandbringto
attention a sum of experiences related to the field of landslide
management with interventions on reducing the effects on society at
large. Keywords: landslide management, natural disaster, prognosis,
post-disaster strategies. 1. PATHS TO LANDSLIDES AS DISASTERS
Societiesatlargethatexperiencedisastershavegonethroughdevelopmentprocesseswhich
havenottakenintoaccounthazardsrelatedtonaturalorsocialphenomenainaproper
manner. The increasing losses experienced by many developing
countries in the last decades reflect that the development in
itself is not leading to sustainability. Thus, some disasters, as
theonesgeneratedbylandslidesinaspecificareaareunaddressedproblemswithinthe
developmentprojectscurrentlyinpractice.Thisremarkisallthemorecorrectwhenthe
followings issues are also worth mentioning [1], [2]:
Continuousviewthatcausesforlandslidesaremostlyrelatedtonaturalhazardsthat
generatesucheventsandthus,theperceptionisthatdisastersoccurexternallyand
independently from the undergoing development process. The
preferred invisibility regarding risk and vulnerability until a
natural event brings them to attention, unlike underdevelopment
that is now addressed inamore visiblemanner at the local, regional,
national and even international level. A dangerous attitude that
nature can be controlled through engineering practices and thus
disaster may at some extent avoided. In a general perspective,
disastersare considered to reflect pre-existing conditionswithinall
componentsofsociety.Infrastructure,services,institutionsandorganizationsarethemost
vulnerable to be affected by a triggering event could be associated
with a natural phenomenon as landslide. Thus, a disaster can be
concluded to be derived from two predispositions:
thepossibilitythatthetriggeringeventtakesplace,usuallynamedahazardatthis
potential state;
anexistingvulnerabilityasthepre-dispositionofpeople,processes,infrastructure,
servicesorsystemsgenerallytobedamagedorultimatelydestroyedbytheeventorthe
incapacity of the society at large to cope with the event/disaster,
once it takes place. 2. DYNAMICS OF VULNERABILITY AND RISK TO
LANDSLIDES
Theneedtodevelopindicatorstomeasurevulnerabilitiesandrisksisamustissuefor
developingcountries which require a strategy toinvest
fundstomaximize the results to risk
reduction.ThescientificcommunityproposedinthecontextoftheInternationalStrategyforDisaster
Reduction(ISDR)andtheformerInternationalDecadeforNaturalDisasterReduction
(IDNDR), the concept of risk bythe following definition: risk is
the probabilityof harmful
consequences,orexpectedlosses(deaths,injuries,property,livelihoods,economicactivity
disruptedorenvironmentaldamage)resultingfrominteractionsbetweennaturalorhuman
induced hazards and vulnerable conditions. Vulnerability is
generally perceived as the predisposition of societies to be
affected and their incapacity to cope with disasters.
Fromadynamicpointofview,vulnerabilitychangescontinuallywithtime.Changesare
related to those factors which can increase it, reduce it or
maintain it in that present state. Bankoff, Frerks andHilhorst
(2004)concluded that vulnerability is generated through social
processes, general issues of developing countries such as class,
gender, ethnicity, poverty can lead to unequal levels or exposure
to risk.
AverypresentissueinRomaniarelatedtoriskgeneratingfactorsisthedevelopment
aggression in terms of urban development on natural slopes in
correlation with a low quality performance of utility supplies in
the area, especially water supply and sewage
networks.Intermsofriskevolution,figure1reflectsanevolutionofrisktolandslidesofsuchareas
reflecting changes in society and the rate of development at large.
Figure 1. A dynamical perspective of risk to landslides towards of
time elapse for such events In the most general perspective,
factors that increase or reduce vulnerability to landslide in a
certain area can be grouped as in table 1. Tab. 1. Potential
factors that generate, increase or diminish vulnerabilities to
landslides Potential factors that can lead to generating
vulnerabilities Potentialfactorsthatcan increase vulnerabilities
Potential factors that can diminish vulnerabilities demographic
differences unequallevelof development inadequateorganization
systems cityexpansion, uncontrolled,unplanned
growthduetomigrationin urban areas development aggression
useofinappropriate technologies lackofspecificcodesfor land control
increasing population densificationofvulnerable
areasinparticulargeographic regions trends in land occupancy
cityexpansion,uncontrolled, unplanned growth previous disasters
poor landslide management moreequaldistributionof political and
economic resources urban planning diversification,multiplicationof
resources targetmarginalandmicro-economicsectorsduring
reconstructionphasesafter disasters landslidemanagement implemented
in vulnerable areas
Inthesimplestway,vulnerabilityisregardedasincapacitytominimizetheimpactsofan
eventleadingtohazardandtocopewithit.Lately,anemergingideatoconsiderregarding
intrinsicpropertiesofvulnerabilityisthenotionthatthedegreeofvulnerabilityofan
infrastructure,acommunity,asocietyorprocessshouldberelatedtothemagnitudeofthe
hazardinquestion[1].Thisideaispresentedgraphicallyinfigure2andcanbeperfectly
related to landslides. Although building codes are conservative in
terms of failure in order to
providesatisfactorysafetyagainstdisasters,landslidesaretriggeringeventswherefailureis
related to a volume of soil with buildings as overburdens in local
areas. Figure 2. Expected degree of damage versus magnitude of the
hazard in question
Preparednessisthemainsolutiontocreateresilientcommunitiestodisasters,landslides
included. Although resistance and resilience may look alike, they
are different concepts and in
landslidecontrolresilienceismoreimportantthanresistance.Resistanceisregardedtobe
relatedtoeconomical,psychologicalandphysicalhealthofsystemsofmaintenance,aswell
asthecapacityofindividualsorcommunitiestowithstandtheimpactoftheevent.Thus,
resistance is related to the capacity of the system to remain
unchanged for an interval of time
aftertheevent/landslidemanifesteditself.Afterthatintervaloftime,thesystemusually
undergoes changes as the event
happened.Resilienceisgenerallydefinedastheabilitytocopewithoradapttothehazardinquestion
viapreparednessandspontaneousadaptationsoncetheeventhasmanifesteditself.Thus,
resilience, in contrast to resistance, is the related to the
capacity of the system to recover to its state prior to the
disaster.
Consequently,vulnerabilitywouldcontinuetobedefinedasthecombinationofthedamage
potential,resilienceandresistance[2].Averyimportantissueisrelatedtothefactthat
different perceptions of vulnerabilities lead to different
approaches on how to handle them. 3.
SOLUTIONSASTREATMENTOPTIONSWITHINLANDSLIDERISK MANAGEMENT
Oncelandslideriskhasbeenanalyzedandevaluated,thetreatmentcomponentisnaturallythe
following step to deal with the landslide event. In this respect,
typical options would include: To accept the risk when risk is
confined to acceptable domain;
Toavoidtheriskwhenanewconstructionisinquestioninthepotentialareaofalandsliderisk,
abandoning the project and looking for alternative construction
sites where risk is acceptable;
Toreducethelikelihoodthatwouldrequireconsolidation/stabilizationmeasuresfigure3to
control triggering aspects [3]; after implementation, the risk
would fall within acceptable domain. To reduce consequences by
setting defensive measures of stabilization; Figure 3. Measures to
consider in slope stabilization/consolidation To introduce
monitoring and warning systems in the area of risk on a permanent
or temporary basis and can be regarded as measures to reduce
consequences as well [4]; To transfer, compensate, or share the
risk, involving insurance companies; All the above mentioned
options should be regarded via their relative costs and benefits.
Combinations
ofoptionsmayalsobeappropriatetoconsider,especiallysincelargereductionsofriskmaybe
achieved.
Asoundlandcontrolisalsolikelytoincludeanemergencyplanthatwillconsistofasequenceof
steps to follow once warning signs indicate the beginning of a new
instability phase [5]. In this case it
isrelevanttoestablishthedifferentwarninglevelsanddependingonthemtosetahierarchyfor
dealing with infrastructure and institutions that will remain in
use during the event. 4. CONCLUSIONS The landslide control is aimed
to generate land value on a safe based system from a potential
disasterrisk.Thelocal/regional/nationalauthoritiesneedcorrespondingregulationstoissue
land use decisions based on land control
guides.Emergencysituationsneedcopingcapacitiestodealwiththeeventwhenistriggered.
Development of coping capacities is the task of policy makers to
include them as investments
onthelongtermdevelopmentofthesocietyitselftodevelopresistanceandresilience
capabilities.
Thenationalguidestocreateriskandhazardzoningrelatedtolandslidesrepresent
instrumentsthatcompletetoacertainextentthenecessarytoolstoimplementthelandslide
control in Romania. Extensive research is focused to contribute
with new approaches related to both landslide probability
assessment as well as stabilization measures effective during and
post-event. TENDINE ACTUALE N COMBATEREA ALUNECRILOR DE TEREN
Managementul eficient al dezastrelor naturaleeste un concept care
stla baza dezvoltrii pe termen lung a oricrei societi. Odat definit
problematica actual a alunecrilor de teren ca parte component a
dezastrelor naturale, se impune identificarea unor metode care s
permit
simultan:mbuntireaprognozelorprivindlocul,momentulicaracteristicileacestor
fenomenenaturale,realizareadescenariiprivindstrategiiledeadoptatnmomentul
declanrii dezastrului, precum i adoptarea unor strategii aplicabile
dup dezastru, n vederea diminurii pagubelor i revenirii la starea
normal. Lucrareaprezint elementecare definesc acestemetode prin
prisma geo-tiinelori aduc natenieexperiene acumulate n domeniul
managementului alunecrilor de teren cu intervenii asupra reducerii
efectelor acestora asupra societii n ansamblu. REFERENCES
1.Cardona, O.C. et al,The need for rethinking the concepts of
vulnerability and risk from a
holisticperspective:Anecessaryreviewandcriticismforeffectiveriskmanagement.In:
Bankoff, G., Frerks, G., Hilhorst, D. (Eds.) Maping vulnerability,
disasters, development and people. Earthscann Publications, London,
2004
2.VillagrandeLeon,J.C.,VulnerabilityAconceptualandmethodologicalreview,
SOURCE, Publications Series of UNU-EHS, nr.4/2006
3.Stanciu,A.,Lungu,I.,FundatiiI:Fizicasimecanicapamanturilor,EdituraTehnica,
Bucuresti, 2006
4.Manea,S.,Evaluarearisculuidealunecareaversantilor,EdituraConspress,Bucuresti,
1998
5.GT019-1998,Ghidderedactareahrilorderisclaalunecareaversanilorpentru
asigurarea stabilitii construciilor. Buletinul Constructiilor.
nr.6/2000. AUTHORS INFORMATION
Assoc.prof.dr.eng.IrinaLungu([email protected]),graduateoftheTechnical
University of Iasi, Civil Engineering Faculty, her primary research
interests are soil-structure
interactionforpilefoundations,soilimprovementbysurfaceanddeepcompaction,slope
management.SheisamemberoftheInternationalSocietyforSoilMechanicsand
GeotechnicalEngineering,(ISSMGE)-1991,InternationalTunnelingAssociation(ITA)
1993,RomanianAssociationforUndergroundStructures(ART)-1993,RomanianSociety
for Geotechnics and Foundations (SRGF) 1996 board member.
Prof.univ.dr.eng. Nicolae Boti ([email protected]) is consultant
professor of geotechnical
andfoundationengineeringattheTechnicalUniversityGh.AsachiIasi,FacultyofCivil
Engineering. His interests are: behavior of structures on active
clays and collapsible soils, soil
improvementbysurfacecompaction,designmethodsforundergroundstructures.Heis
memberoftheInternationalSocietyforSoilMechanicsandGeotechnicalEngineering,
ISSMGE(1991),InternationalTunnelingAssociation(ITA)1993,RomanianAssociation
forUndergroundStructures(ART)-1993-boardmemberandformerpresident,Romanian
Society for Geotechnics and Foundations (SRGF) 1996 board member;
titular member of the Romanian Association of Scientists (AOS)
1985.
Prof.univ.dr.eng.AnghelStanciu([email protected])isprofessorofgeotechnical
engineeringandfoundationattheTechnicalUniversityGh.AsachiofIai,Civil
EngineeringFaculty.Hisprimaryresearchinterestsare:reinforcedsoilsolutionsfor
transportationinfrastructure,newapproachesinslopestabilityanalysis,designmethodsfor
undergroundstructures.HeismemberoftheInternationalSocietyforSoilMechanicsand
GeotechnicalEngineering(ISSMGE)-1991,InternationalTunnelingAssociation(ITA)
1993,RomanianAssociationforUndergroundStructures(ART)-1993-boardmember,
Romanian Society for Geotechnics and Foundations (SRGF) 1996 board
member; titular
memberoftheRomanianAssociationofScientists(AOS)-1985;fullmemberofthe
Romanian Academy of Agricultural and Forest Sciences Gh. I. Sisesti
2002.
Drd.eng.OanaDonciu([email protected])isaphDstudent,graduateoftheTechnical
UniversityGh.AsachiofIai,CivilEngineeringFaculty,herstudiesconcernreinforced
soilstructures.SheismemberoftheInternationalSocietyforSoilMechanicsand
GeotechnicalEngineering(ISSMGE),InternationalTunnelingAssociation(ITA),Romanian
SocietyforGeotechnicsandFoundations(SRGF),RomanianAssociationforUnderground
Structures (ART).
