Presentation at the 10th International Symposium on Landslides and Engineered Slopes entitled "Temporal prediction in landslides – understanding the Saito effect"
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Transcript
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Temporal prediction in landslides – understanding the Saito effect
David PetleyDurham University, United Kingdom
Derek PetleyWarwick University, United Kingdom
Robert AllisonSussex University, United Kingdom
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Worldwide fatal landslides - 2007
Large fatal landslides occur mainly in less developed countriesPrediction may be a key tool to reduce their impact
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The Saito Effect
• During final failure, some slopes show a hyperbolic increase in displacement rate with time
• Manifested by a linear trend in a plot of inverse displacement rate against time
• This is the Saito effect • Can be used to predict the
time of failure if (and only if) we understand the when and why it applies
Time
Dis
pla
cem
ent
ra
te
Time
Dis
pla
cem
ent
ra
te-1
Failure
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Theory one: state and rate dependent frictionFriction inversely related to strain rate
What causes the Saito effect?
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Theory two: crack growth processesBehaviour related to growth of shear surface through subcritical crack
growth
What causes the Saito effect?
Diagram from: Scavia, C. 1995. A method for the study of crack propagation in rock structures. Géotechnique, 45, 447-463.
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Movement analysis in the laboratory
Aim: to simulate movement styles with increasing pore pressures using stress path testing