NIIGATA, JAPAN; EARTHQUAKE INDUCED LIQUEFACTION

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NIIGATA, JAPAN EARTHQUAKE INDUCED LIQUEFACTION

• By Nick Sammons
• and Paul Simkin
• February 2008

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CONTENT

• WHAT IS EARTHQUAKE INDUCED LIQUEFACTION?
• WHY DOES LIQUEFACTION OCCUR?
• WHERE DOES LIQUEFACTION OCCUR?
• CASE STUDY NIIGATA, JAPAN
• ENGINEERING SOLUTIONS

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WHAT IS EARTHQUAKE INDUCED LIQUEFACTION?

• The change in soil behaviour from a solid state
  to a liquid state
• Strength and stiffness of soil are reduced
• This phenomenon is often responsible for large
  amounts of damage caused during earthquakes

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WHY DOES LIQUEFACTION OCCUR?

1. Earthquake vibrates ground
2. No time for water to be squeezed out
3. Water becomes trapped
4. Water pressure increases
5. Effective stress decreases
6. Particles act individually

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WHY DOES LIQUEFACTION OCCUR? (2)
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WHERE DOES LIQUEFACTION OCCUR?

• Saturated soils
• Most commonly occurring in
• Sand
• Low-lying areas
• Near bodies of water
• Areas susceptible to earthquakes and repetitive
  vibrations

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CASE STUDY NIIGATA, JAPAN

• 16 June 1964
• Magnitude 7.5 (Richter scale)
• 2000 houses destroyed
• 28 lives lost
• Also triggered a tsunami, completely wiping out
  the port of Niigata

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CASE STUDY NIIGATA, JAPAN (2)

• Ground failure occurred near Shinano river bank
• Apartment buildings suffered bearing capacity
  failures and tilted severely

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CASE STUDY NIIGATA, JAPAN (3)

• Liquefaction spread
• Foundations of Showa bridge moved laterally
• Simply supported spans became unseated and
  collapsed

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ENGINEERING SOLUTIONS

• Avoid
• Study liquefaction susceptibility maps
• Adapt in design
• Improve foundations
• Deeper piles
• Foundation map transfer loads to stronger soils

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ENGINEERING SOLUTIONS (2)

• Improve soil
• Dynamic consolidation
• Drainage and water table reduction
• Surcharge to increase effective stress

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REFERENCES

• Waltham, T. (2002). Foundations of Engineering
  Geology. Routledge, UK.
• http//www.abag.ca.gov/bayarea/eqmaps/liquefac/liq
  uefac.html
• http//www.ce.washington.edu/liquefaction/html/ma
  in.html
• http//nisee.berkeley.edu/bertero/html/damage_due_
  to_liquefaction.html