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
Cassas Landslide, Italy - Volume 20 - 30 million m3
- Lenght appx. 1.8 Km- Average slope 50 to 55 %- Slide depth appx. 60 m
Meanwhile the monitoring continued...and in Fall 2000 we witnessed what we had calculated!
Cassas LandslideRainfall 1998-2002
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.
¥ • 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.
