A risk evaluation approach for an active rock slide: the Gascons coastal rock slide, Québec

Jacques Locat, Catherine Cloutier, Michel Jaboyedoff

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Transportation Geotechnique

ABSTRACT: he Chemtown of Chrecent histSince 200conditions geological frequency-uncertaintyapproacherate of mov

RÉSUMÉ: Le cheminChandler. 1998, le gsupérieurs2009 afin dacquises, fréquence-il est possmitigation.déplaceme 1 INTR The railroacquired insupport froof an efforthe GaspéDaniel-Ga1) is knowThe Gascosedimentaalternatingless frequ1980). Mol™Anse-à-PMass caused byplanar andinstability more or lefailure (semore detarailroad wwere appaabove thExtensomeevaluatiothe GascLocat & Cathire d™étude sué Laval, Québaboyedoff or Research oCT min de fer de lahandler. It hastory, at least o09, the site hawith the inteand hydrogeo-probability any, it is possibes. One of the vements in an n de fer de la GLe volume du glissement a cs à celles mesude suivre les pnous avons dé-probabilité et sible de parven L™un des facents d™un glisseRODUCTION ad between Mn 2007 by locaom Provincial art to support theé Peninsula. A scons (mile 30wn to present vaons site is locary rocks of Sg beds of limeuently sandstoost of the rockPierre-Loiselle Fmovements oy coastal erosid toppling failuto the upper pess along the e Cloutier et aails). It is interwas completed arent on a 1933he railroad eter data obtaon approcons coaserine Cloutierur les risques bec, Qc, Canaon Terrestrial Ea Gaspésie is s a volume of 4one collapse evas been instrunt to develop ological modelsnd expert judgble to come upmost limiting faactive slide. Gaspésie traveglissement esconnu un effonurées actuellemressions d™eauéveloppé une asur le jugemennir à une analyscteurs limitatifsement actif. Matapedia andal municipalitieand Federal goe socio-economportion of the 0.5 of the Chaarious signs ofcated along a cSilurian age coestone, shale, one (Bourquekslide is takinFormation. bserved in thion which locaures that evenpart of the slobedding planal. 2010 and Lresting to pointin 1911 and 3 aerial photog(Locat and ained in 1993-ach for astal rock r naturels (LERada Environment passing throug410 000 m3 anvent took placemented in ordwarning criters, we developegement approap with a meaactors is our laerse un glissemst d™environ 410ndrement majement. Dans le bu, les déplacemapproche semi-nt d™expert. Cese sensée afins de l™analysed Gaspé has es with the finaovernments asmic developmerailroad, near andler division,f mass movemcoastline formeonsisting mainconglomerate,e and Lachag place withinhis sector are ally triggers smntually transfeope which is fae still as a wLord et al. 201t out here thalittle or no fissgraphs of the sCouture 191994 for the Pan active slide, QuRN), Départe(CRET), Univgh a very slownd is moving ae involving smder to monitor ria. Base on ted a semi-quanaches. This waningful analysack of tools enament de terrain0 000 m3 et il seur d™une partibut de dévelopments et les con-quantitative pot article montren de supporter est le manqbeen ancial s part ent of Port-, Fig. ents. ed in nly of and mbre n the first maller r the ailing wedge 0 for at the sures ector 995). Petit-Massblockto 0.4abouThat 1998InoperaIt hasCanaFroesOppik(Sartoprojemonitout amanaThmain accelpapestrateat thisprelimregaraccelrock uébec ment de géolversity of Lauw moving coasat an overall amaller volumes pore pressurethis type of dantitative approawork will illustrsis supporting abling the adeqn actif, mais trèse déplace à ue de la falaisepper des critèrenditions météoour évaluer le e que malgré dla gestion du rue d™outils afisif (Fig. 2) indick facing the oce4 mm/d which it to fail in the part of the slo. n order to ination, the Gascs been designeada such as se 2009), Aknkofer et al. 2ori et al. 2003ct involves twtoring system ea risk evaluatioagement. he Gascons schallenge isleration could tr will address egy for the Gass point that actminary and invrding the hazleration of thelogie et de géusanne, Lausatal rockslide lonnual rate of abut with tempoes, displacemeata and on ouach for risk evarate that eventhe evaluationquate predictioès lent, qui se une vitesse moe qui a été pres d™alerte, le srologiques. À prisque. Elle sedes sources d™irisque et l™évaln de prédire cated that the mean near the raindicated that tnear future (Loope did failed crease the scons project (2ed using experiTurtle Mountanes rockslide i2009), and ro3, Rouiller et awo main objeenabling warnion that could plide is a very s to assess take place. In the developmscons slide. It tual risk evaluavolved large uzard compone sliding massénie géologiquanne, Switzerocated 25 km babout 15 mm. orary faster moents, and enviur understandialuation based n with some n of potential on of the evolusitue 25 km à oyenne de 15 mrécédé par dessite a été instrupartir des conne base sur les aincertitudes imuation des mél™évolution desmovements of aailroad were atthis part of the ocat and Coutufour years latsafety of the 2009-2013) wasiences at varioain slide (Mon Norway (Blickslides in Sal. 2004). Theectives: (1) dng criteria, andprovide the basslow moving if and whenthis context, thment of a risk eis important toation values aruncertainties pent and the s into a collapue, rland before the During its ovements. ironmental ing of the on both a significant mitigation tion of the l™ouest de mm/an. En s vitesses umenté en aissances approches mportantes, éthodes de s taux de a 10-20 m about 0.3 slope was ure 1995). ter in July railroad™s s initiated. us sites in oreno and ikra 2008, witzerland e Gascons develop a d (2) carry sis for risk slide. The n a rapid he present evaluation o underline re still very particularly potential pse event.

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