Sources of Geotechnical Risk

1. SOURCES OF
GEOTECHNICAL RISK
A talk by Dr Fred Baynes, President of IAEG
Point 1: Cost or time over-runs occur on ~20 to 50% of
projects.
Point 2: Project staff are probably a greater source of
risk than the ground conditions
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2. A “dry dock” under construction
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3. A foundation
“problem”
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4. Landslides affecting housing
and infrastructure
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5. Teton Dam - 5 June 1976 - about 4 hours after leak
appeared - 11 people were killed
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6. West Driefontein Mine – December 1962 – a 3 story
crusher disappeared – 29 lives lost
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7. ABERFAN
• Debris flow of colliery
spoil
• 3rd slide on 21
October 1966
• 140,000 yd3 hit a
primary school
• 144 killed including
116 kids under 10
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8. OUR PERFORMANCE?
• Geo-engineering risks:
–Cost or time over-run ~20 to 50% of
projects
–Physical failure ~ 1 to 2% for civil, ~
up to 20% for mining projects
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9. Geotechnical Risk
“the risk to building and
construction work created
by the site ground
conditions (Clayton 2001)”
Risk = Hazard x Consequence
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10. Is the risk created by
the site ground
conditions or by the
work practices
permitted by people?
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11. Different sources of risk within the organization
PROJECT MANAGEMENT
PROJECT RISKS
GEOTECHNICAL RISKS
TECHNICAL CONTRACTUAL
GEOLOGICAL ANALYTICAL PROPERTIES
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12. Type of Geotechnical Risk Hazard
Poor management of
Project management
entire geo-engineering process
Poor management of site investigation and
Contractual
contract documentation
Analytical Unreasonable analytical model chosen
Unreasonable design
Properties
values chosen
Technical Unforeseeable geological details
Geological Inherently hazardous ground conditions
Unforeseen ground
conditions
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13. Unforeseen vs unforeseeable – karst cavities
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14. “Unforeseen”
vs
“contractually unforeseen”
Remember that Saint Thomas
More described lawyers as “a
sort of people whose
profession it is to disguise
matters”
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15. Green - people are the source Pink – the ground is the source
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16. Geotechnical Risk
“the risk to building and construction work
created by the site ground conditions
(Clayton 2001)”
but probably more often created by the
project staff not understanding the ground
conditions!
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17. People are the main source of geotechnical
risk – what kind are on your project?
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18. Geotechnical risk management techniques
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19. CONCLUSIONS
• Cost or time over-run ~20 to 50%
• Physical failure ~ 1 to 2% for civil, ~ up to
20% for mining projects
• Risks can be systematically considered
• Project staff are probably a greater source of risk
than ground conditions
• Established techniques exist and a team of
engineering geologists & geotechnical engineers
can contribute
• Challenge is to manage all the sources of risk
• Training and education is a key requirement
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