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The Cassas Landslide and its impacts on an international & Olympic transportation corridor: studies, monitoring, solution and crisis plans Second World Landslide Forum Ð 3-7 October 2011, Rome Franco Oboni, Claudio Angelino, Bartolomeo Visconti
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Cassass presentation WLF2 Rome

Jun 05, 2015

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This example, that we presented at the WLF2 Conference in Rome, constitutes a complete and fully developed which included the following phases:
probabilistic behaviour forecast,
behaviour monitoring (which luckily allowed to actually “see happen” what we had predicted a few years earlier),
Risk Based Decision Making (RBDM), and finally
implementation of mitigative and crisis management plan.

Interestingly, in a curious turn of events, while doing some reconnaissance work on the landslide, two of us almost lost our lives in a helicopter crash. Risk managers are unfortunately not immune to risks...and somehow it was a good lesson for us to be in the “victim role” that day.
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Page 1: Cassass presentation WLF2 Rome

The Cassas Landslide and its impacts on an international& Olympic transportation corridor: studies, monitoring,solution and crisis plans

Second World Landslide Forum Ð 3-7 October2011, Rome

Franco Oboni, Claudio Angelino, Bartolomeo Visconti

Page 2: Cassass presentation WLF2 Rome

Cassas Landslide, Italy - Volume 20 - 30 million m3

- Lenght appx. 1.8 Km- Average slope 50 to 55 %- Slide depth appx. 60 m

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Meanwhile the monitoring continued...and in Fall 2000 we witnessed what we had calculated!

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Cassas LandslideRainfall 1998-2002

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The selected drainage tunnel proved to be a difficult engineeringtask due to mountain environment and geotechnical challenges.The finished tunnel has performed satisfactorily for 5 years now,draining more than 1300 m 3/mo of water from the slide body withpositive effects in terms of overall stability.

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¥ • Probabilistic geotechnical analyses have been successfully coupled withmonitoring data.

• Following calibration and observation good understanding of the parametersinfluencing and dictating the behavior of the slope was achieved.

• The study also aimed at finding a correlation between antecedent rain, net ofevapo-transpiration, and the slope response, in terms of movements.

• Rains over a period of 300 days were found to display the strongest correlationwith inclinometers data.

• The strong correlation made it possible to propose a relationship between netantecedent rain and the velocity in a given point.

• As a result of the quantitative risk assessment (QRA), a drainage tunnel wasdesigned and constructed to mitigate potential reactivations due to water tableheave in case of long rainy seasons.

• The finished tunnel has drained more than 1300m 3 per month of water during 5years from the slide body with positive effects in terms of overall stability.