THE LEANING TOWER OF PISA
GEOTECHNICAL ENGINEERING
Why Geotechnical Engineering?
“Virtually every structure is supported by soil or rock.
Those that aren’t - either fly, float, or fall over.” -Richard Handy, 1995
Case Study I: Building Foundation
Soft Clay Soil
20 ft of sand and gravel
15-ft soft fill and organic silt
Firm Soil or Bedrock
Weight of building (DL + LL) = 37,000 tons
Initial estimated settlement = 1 ft
Weight of excavated soil = 29,000 tons
Estimated settlement due to the net load of
clay (37,000 – 29,000 = 8,000 tons) = 2-3 in.
75 ft
Source: Lambe & Whitman, 1969
Building 10 on M.I.T.’s Campus – Photo by Professor Zoghi, Sept. 1984
•How deep?
•Size of the footing (mat foundation)?
•Groundwater table?
•Dewatering?
•Braced excavation?
•Damage to adjacent buildings?
•Quantity and rate of the estimated settlement?
•Stress distribution?
•Design bearing capacity?
Design and Construction Issues
•Pile type?
•How deep?
•Spacing?
•Maximum allowable load?
•Pile efficiency?
•Driving/drilling?
•Optimum sequence of driving piles?
•How much variation from vertical?
•Adjacent buildings?
Alternative Foundations
Case Study II: Earth Dam
Source: Lambe & Whitman, 1969 Zoned Earth Dam
• Dimensions? (Most economical design)
• Thickness of the rock facing and gravel to keep swelling of clay core
to a tolerable amount?
• The moisture content and compaction technique (lifts, equipment,
etc) to place gravel and clay?
• Permeability and seepage characteristics of the dam?
• Consolidation and settlement characteristics of underlying soil?
• Shearing strength parameters?
• Potential leakage under and through the dam?
• Factor of safety of upstream and downstream slopes?
• Rapid draw down effect?
• Seismic activity?
Design and Construction Issues
http://www.geol.ucsb.edu/~arthur/Teton%20Dam/welcome_dam.html
TETON DAM
The Teton Dam, 44 miles northeast of Idaho Falls in
southeastern Idaho, failed abruptly on June 5, 1976. It
released nearly 300,000 acre feet of water, then flooded
farmland and towns downstream with the eventual loss
of 14 lives, directly or indirectly, and with a cost
estimated to be nearly $1 billion.
Teton Dam Failure - Flood waters advancing through Rexburg, Idaho.
Landslides
In excess of $1 billion in damages and 25 to 50 deaths each year in U.S.
Loss of Support⇒Bridge Collapse – Kobe EQ
Annual Damage in the U.S.
Geo-Environmental
• Municipal Solid Waste
� Approx. 3.6 lbs trash per
person per day
� Total trash = 216 million
tons
� Make up:
40% Cardboard
18% yard waste
9% metals
8% plastic
others
Landfills
Source: Coduto, 1999
How to Prepare?
HISTORICAL PERSPECTIVE
Geotechnical Hall of Fame:
http://www.ejge.com/People/HallFame.htm
Charles Augustin de Coulomb
• Grandfather of the Soil
Mechanics
• 1736-1806 (France)
• Friction and cohesion
concepts
• Lateral earth pressures on
retaining walls
• Structures, Hydraulics,
Mathematics, Electricity,
etc.
William John Maquorn Rankine
• 1820-1872 (Scotland)
• Thermodynamics and
soil mechanics
• Lateral earth pressure
theory
• Pioneering role as an
engineering educator
Karl von Terzaghi
• The Father of Soil Mechanics
• 1883 (Prague) – 1963 (Massachusetts)
• Coined the phrase…
• First publication in 1925
• Great many contributions
Arthur Casagrande
• 1902 – 1981
• Worked closely with Terzaghi
• Started soil mechanics at Harvard
• Received numerous awards
• Fundamental soil mechanics problems…
Ralph Brazelton Peck
• 1912 – Winnipeg, Canada
• Co-authored a textbook
with Terzaghi
• Initially a bridge
designer…
• Several decades as a
pioneering foundation
engineer and educator
• Numerous awards
Alec Westley Skempton
• 1914-2001 (UK)
• Established soil
mechanics at Imperial
College
• Soil mechanics
problems, rock
mechanics, geology,
and history of civil
engineering
Nilmar Janbu
• 1920 -
• NTNU – Norway
• Ph.D. student of Casagrande at Harvard
• Slope stability problems – Janbu Method
• Landslides in quick- clay
Laurits Bjerrum
• 1918-1973
• The First Director of
NGI (1951-1973)
• Quick clay
• Progressive failure of
slopes
• A “Giant”
Harry Bolten Seed
• 1922 – 1989
• Father of Geotechnical
Earthquake
Engineering
• UC Berkley
• Pioneering work in
Geohazards