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Jean-Louis Briaud – Texas A&M University
Washington
Monument
Case History
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Jean-Louis Briaud – Texas A&M University
CREDITS
• Hugh Lacy, Mueser Rutledge, New York
• Briaud J.-L., Smith B., Rhee K.-Y., Lacy H., Nicks J.,
2009. “The Washington Monument Case History”,
International Journal of Geoengineering Case Histories,
http://casehistories.geoengineer.org, Vol.1, Issue 3,
p.170-188.
Efforts have been made to give credit for illustrations and text obtained from other sources. If you find credit missing on this document, please contact us so we can address the issue.
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Jean-Louis Briaud – Texas A&M University
HISTORY
• George Washington, 1st President of USA
• Constructed in three phases:
• 1848: 1st phase = construction begins
• 1858: construction stops = no more money
• 1879: 2nd phase = underpinning
• 1880: 3rd phase = completion of the shaft
• 1884: construction completed
• Settlement measured since 2nd phase in 1879
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Jean-Louis Briaud – Texas A&M University
CONSTRUCTION
• Began in 1848 with architect
Robert Mills
• Original foundation consisted of a
stair stepped pyramid made of
blue gneiss blocks
• Shaft made of marble blocks
• Construction was halted in 1858
with the shaft at a height of 55.5
m due to lack of funds
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Jean-Louis Briaud – Texas A&M University
• Construction resumed in 1879, after
the Civil War with Lt. Col. Casey of the
US Army Corps of Engineers
• Casey considered the original
foundation inadequate and decided to
underpin it.
• Increased foundation area
• Founded on stiffer soil
• The Monument was completed in 1884
CONSTRUCTION
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Jean-Louis Briaud – Texas A&M University
DIMENSIONS
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Jean-Louis Briaud – Texas A&M University
LOAD vs TIME
First Phase of Construction
Underpinning
Final Phase of Construction
0
100
200
300
400
500
600
700
1845 1850 1855 1860 1865 1870 1875 1880 1885 1890
Time (years)
Lo
ad
(M
N)
0
100
200
300
400
500
600
700
1997 2007
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Jean-Louis Briaud – Texas A&M University
WEIGHT AND PRESSURE
• Weight of original foundation: 70 MN (Pressure =
118 kPa)
• Weight at end of Phase 1: 305 MN (Pressure =
513 kPa)
• Weight of new foundation: 153.8 MN
• Final weight of Washington Monument: 607.7 MN
(Pressure = 465 kPa)
• San Jacinto Monument: 313 MN
• Tower of Pisa: 142 MN
• Eiffel Tower: 94 MN
• Earth terrace: 86.4 kPa
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Jean-Louis Briaud – Texas A&M University
PRESSURE vs. TIME
First Phase of Construction
Un
derp
inn
ing
Fin
al
Ph
ase o
f
Co
nstr
ucti
on
0
100
200
300
400
500
600
1845 1850 1855 1860 1865 1870 1875 1880 1885 1890
Time (years)
Pressu
re (
kP
a)
Completely Distributed Total Pressure
Underpinning-Only Total Pressure
0
100
200
300
400
500
600
1997 2007
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Jean-Louis Briaud – Texas A&M University
51 SOIL BORINGS - DEEPEST 38 m
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Jean-Louis Briaud – Texas A&M University
SOIL STRATIGRAPHY
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Jean-Louis Briaud – Texas A&M University
SOIL PROPERTIES
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Jean-Louis Briaud – Texas A&M University
SOIL PROPERTIES
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Jean-Louis Briaud – Texas A&M University
SOIL PROPERTIES
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Jean-Louis Briaud – Texas A&M University
SOIL PROPERTIES
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Jean-Louis Briaud – Texas A&M University
BEARING CAPACITY
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Jean-Louis Briaud – Texas A&M University
• Actual Pressure under old foundation = 513 kPa
• Ultimate pressure Pu under old foundation (Clay)
• Su = 72 kPa (from N=12 bpf, Kulhawy and Mayne, 1990), D = 2.34
m (at time of maximum loading), Nc = 6.2 (square foundation)
• Then Pu = 491 kPa
• Ultimate pressure Pu under old foundation (Sand) (Briaud and Gibbens, 1999):
• Blow count (N) = 12 bpf, Then Pu = 900 kPa
• FS = 0.96 – 1.75
P N S Du c u
75u
blowsP kPa N
ft
BEARING CAPACITY
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Jean-Louis Briaud – Texas A&M University
STRESS INCREASE WITH
DEPTH BY 3D FEM (ABAQUS)Old foundation
(After Phase 1)
Underpinned foundation
(Before & after Phase 3)
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Jean-Louis Briaud – Texas A&M University
CONSOLIDATION CURVE
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Jean-Louis Briaud – Texas A&M University
RECONSTITUTED SETTLEMENT
Time in Years
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Jean-Louis Briaud – Texas A&M University
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