ENV-3A1Y: Natural Hazards: 2006 - 7

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ENV-3A1Y Natural Hazards 2006 - 7

• Landslide Hazards
• N.K. Tovey
• ?.?.????

14,607 days ago today Exactly 40 years ago next
Saturday
Landslide on Main Highway at km 365 west of Sao
Paulo August 2002
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ENV-3A1Y Natural Hazards 2006 - 7

• Lecture 1 Wednesday Week 42
• Introduction
• Landslides as a Hazard and their consequences
• background to why they occur
• Lecture 2 Thursday Week 4 12 13 EF 1.01
• Types of Landslide
• Lecture 3 Thursday Week 4 14 - 15
• Landslide Warning systems
• Lecture 4 Wednesday Week 5 09 10 EF 1.01
• Landslide and Slope Management
• Field Excursion Thursday Week 5 12 17
• Bring Field Clothing and a packed lunch

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ENV-3A1Y Natural Hazards 2006 - 7

• Aims of the course
• An introduction to Landslide Hazard Management
• Factor of Safety
• the causes
• Why they occur
• Can we predict them
• the consequences
• The types of landslide
• Landslide Warning
• Development of the Hong Kong System and what was
  learnt
• Strategic Planning for the future
• Slope management

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ENV-3A1Y Natural Hazards 2006 - 7

• Landslides as a Hazard
• Grossly Under Represented as a Hazard
• Often treated as a secondary issue
• e.g Rain Storm Disasters of 18th June 1972 in
  Hong Kong
• 2 major landslides each killing over 60 people
• No one was killed by drowning/flooding

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ENV-3A1Y Natural Hazards 2006 - 7

• Landslides associated with
• Heavy Rain (Tropical Cyclones)
• 500 landslides affected man in Hong Kong 28th
  May to 2nd June 1982.
• As a result of NKTs actions Yuen Mo village
  ceased to exist.
• Earthquakes
• Cause liquefaction and rise of pore pressures
• Volcanic Eruptions

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ENV-3A1Y Natural Hazards 2006 - 7

• 14607 days ago today at 0915
• N K Tovey a second year PhD student was
  listening to a lecture by Andrew Schofield.
• Theme of lecture was Landslide Hazards
• At 0915 he turned his attention to a landslide
  disaster which had occurred a few year earlier in
  Belgium.
• A colliery tip collapsed killing around 20 people
  in the village.
• At precisely the time he was speaking about
  the disaster
• gtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgtgt

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ENV-3A1Y Natural Hazards 2006 - 7

• Aberfan 21st October 1966
• Tip 7 collapsed, engulfed Pantglas School and
  parts of the village killing 144 mostly children

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ENV-3A1Y Natural Hazards 2006 - 7

• Geotechnics the discipline needed for detailed
  analysis
• "the application of the laws of mechanics and
  hydraulics to the mechanical problems relating to
  soils and rocks"
• Factor of Safety (Fs)

Forces resisting landslide movement arising from
the inherent strength of the soil.
Fs
Forces trying to cause failure (i.e. the
mobilizing forces).
Fs gt 1 stable
But is it?
Fs 1 just stable
But is it?
Fs lt 1 unstable
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berms
Heave at toe

• Landslide in man made Cut Slope at km 365 west of
  Sao Paolo - August 2002

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berms
Steep scar to rotational failure
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Geochemistry
Landslide