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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

Cassass presentation WLF2 Rome

Jun 05, 2015



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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  • 1. Second World Landslide Forum 3-7 October2011, RomeThe Cassas Landslide and its impacts on an international& Olympic transportation corridor: studies, monitoring,solution and crisis plansFranco Oboni, Claudio Angelino, Bartolomeo Visconti

2. Cassas Landslide, Italy- Volume 20 - 30 million m3- Lenght appx. 1.8 Km- Average slope 50 to 55 %- Slide depth appx. 60 m 3. Meanwhile the monitoring continued...and in Fall2000 we witnessed what we had calculated! 4. Cassas LandslideRainfall 1998-2002 5. 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. 6. 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.