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RONALD FRASER SCOTT
1929–2005
Elected in 1974
“For contributions to the theory and application of soil mechanics.”
BY PAUL C. JENNINGS AND PAMELA J. SCOTT
R ONALD FRASER SCOTT, Dotty and Dick Hayman
Professor of Engineering, Emeritus, at the California Institute
of Technology in Pasadena died on August 16, 2005, at the age
of 76. He was elected to the National Academy of Engineering
in 1974 for “contributions to the theory and application of soil
mechanics.”
An internationally recognized expert on the mechanics of
soils, Ron worked on a wide range of problems, including the
freezing and thawing of soils, the characteristics of lunar and
Martian soils, the characteristics of ocean-bottom soils, soil
liquefaction, the dynamics of landslides, and the mechanism of
earthquake-caused sand blows. He pioneered the use of
centrifuges in the United States for studying the behavior of
soil structures, such as earthen dams, under both static and
dynamic loading.
Ron was born in London, but grew up in Perth, Scotland,
where, among other things, he dug potatoes during World War
II when the men were all in the service. He earned a bachelor’s
degree in civil engineering from the University of Glasgow in
1951 and then came to the United States where he earned an
Sc.D. in civil engineering (soil mechanics) from the Massachusetts
Institute of Technology in 1955. After graduation, he worked
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252 MEMORIAL TRIBUTES
for the U.S. Army Corps of Engineers on the construction of
pavements on permafrost in Greenland and for the engineering
consulting firm of Racey, McCallum and Associates of
Toronto.
Ron met his wife, Pamela Wilkinson, a flight attendant for
American Airlines from Bedfordshire, England, on his way to
Caltech for an interview. They were married on May 28, 1959,
and subsequently had three sons, Ron and twins Craig and
Grant, and then nine grandchildren. Ron rose through the
academic ranks at Caltech to full professor in 1967 and became
Hayman Professor in 1987. In 1998, he became professor
emeritus.
Ron had a deep understanding of theoretical aspects of the
mechanics of solids, and his research was characterized by
thorough study of underlying scientific issues. He was always
motivated, however, by practical problems and was adept at
showing how his research results could be useful in engineering
practice. He also had a knack for explaining complicated
concepts in soil mechanics to the general public.
In the 1960s, Ron became involved in evaluating the
properties of lunar soil to determine if manned spacecraft could
land safely on the lunar surface. At the time, there was wide
speculation; some thought the Moon was covered with a thick
layer of fine powder that would not support a landing vehicle
or a man on the surface; others believed that the surface was
quite firm. In 1963, Ron proposed that NASA include an
experiment on soil mechanics on a Surveyor spacecraft. The
proposal was accepted, and Ron became the principal
investigator.
The experiment was first flown in 1967 on Surveyor III. The
surface sampler, as it was called, resembled a small backhoe
shovel mounted on an extensible trellis. After the successful
landing, Ron wrote that “for the next two weeks, Floyd [JPL
engineer Floyd Roberson] and I happily and sleeplessly played
with the lunar soil on the inside surface of a 650-foot diameter
crater.”
Many readers will remember the pictures of the “scoop”
digging into the lunar soil relayed from the Moon. Although it
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RONALD FRASER SCOTT
looked like a toy, the scoop was, in fact, an ingeniously designed
instrument that made significant measurements of the strength,
cohesion, and density of lunar soil. It also provided information
about the homogeneity of the soil and variations in soil
properties with depth. Because the sampler could exert pressure
when the scoop door was closed, it was possible to use it to
distinguish between rocks and clods.
From these tests, Ron concluded that the lunar soil at the site
was fine-grained, with a small amount of cohesion, an internal
angle of friction of 35 degrees—properties similar to those of
damp terrestrial sand—and that it was safe to walk on. When
Neil Armstrong stepped onto the surface of the Moon, his
famous words, “That’s one small step for a man, one giant leap
for mankind,” were followed by “I sink in about an eighth of
an inch. I’ve left a footprint on the surface,” words that
confirmed Ron’s conclusions.
This story has a postscript. In November 1969, Apollo 12
landed close to Surveyor III, and part of the mission of astronauts
Conrad and Bean was to retrieve various parts of the Surveyor
spacecraft. Although it had not been included in the plans,
Conrad also retrieved the scoop and brought it back to earth.
Upon learning this, Ron remarked, “If I had known I was going
to see it again, I would have left the scoop completely packed
with lunar soil.” A similar scoop, also designed by Ron, was
used on the Viking spacecraft in 1976 to investigate the
properties of Martian soils.
In the 1970s, Ron became convinced that centrifuges should
be used in the United States to advance knowledge of the
dynamic properties of soils and soil structures, particularly
when subjected to strong earthquake motions. Centrifuges had
been used to study soils in the Soviet Union, but with the
exception of P. B. Bucky at Columbia, who used them to study
problems related to mining, they had not been used in the
United States. A centrifuge is a valuable tool, Ron argued,
because the mechanical properties of soils depend on the
overburden pressure. For example, deeper soils, which are
under more pressure than surface soils, have higher failure
levels than the same kind of soil near the ground surface. Thus
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254 MEMORIAL TRIBUTES
to test a 1/100 scale model of an earthen dam made of the same
material as the full-scale prototype, the soil must be subjected
to an effective gravity 100 times the gravity of the Earth.
In 1975, Ron convened a workshop at Caltech to bring the
potential value of this method to the attention of U.S. researchers.
The conference introduced the first research in the United States
using centrifuges, and they are now widely used and
acknowledged to be extremely valuable for studying soil
mechanics. In his introduction to the workshop, Ron’s famously
dry sense of humor was on display in an illustrated history of
the uses of centrifuges in science and engineering, chiefly in
medicine. At the time, centrifuges were used for the treatment
of the mentally ill, and a spinning platform had been patented
for using centrifugal force to facilitate childbirth.
For Ron’s first centrifuge research, he adapted a small
centrifuge he had obtained from NASA for research on soil
mechanics. Installed on the roof of a Caltech building, the
machine had a 40-inch radius and could accommodate models
whose largest dimensions were approximately one foot. In a
series of experiments in the late 1970s and early 1980s, Ron and
his coworkers—students, postdoctoral fellows, and engineers
from industry—performed experiments on the performance of
piles for offshore drilling structures, the behavior of anchors
for the support of guyed offshore towers, dynamic pressures
on retaining walls during earthquakes, the mechanics of fault
rupture in rock and alluvium, and the earthquake behavior of
foundations and footings.
These experiments were not easy to perform. The modeling
requirements meant that time in the model had to run much
faster than time in the prototype. For example, a 20 to 30 second
earthquake accelerogram had to be compressed into 2 or 3
seconds of model excitation, and it had to be applied by a small
shaker in a high-g environment in a bucket spinning many times
a second within a closed cage. Data, typically strains and
pressures, were extracted electronically through sliding contacts
at the central shaft, and time-dependent displacements were
recovered through the use of mirrors and high-speed
photography.
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The results were very important in advancing the state of
soil mechanics. Because large earthen structures could not be
subjected to failure-level stresses, the results of the centrifuge
tests provided the best available experimental confirmation of
engineering calculations and design methods.
Another of Ron’s interests was landslides and dam failures.
He was a consultant on the Baldwin Hills Dam failure in Los
Angeles in 1963, and he studied the disastrous Bluebird Canyon
landslide in Laguna Beach in 1978. By studying a small landslide
in Los Angeles, which moved slow enough to be analyzed, he
was able to make measurements of the motion on the slide plane
and document the observed pulse-like character of the
sliding.
Ron received many awards for his contributions to the
advancement of soil mechanics, among them the Huber
Research Prize, the Norman Medal, and the Thomas A.
Middlebrook Award from the American Society of Civil
Engineers (ASCE) and the Newcomb Cleveland Award from
the American Association for the Advancement of Science. He
was the ASCE Terzaghi Lecturer in 1983 and the British
Geotechnical Society Rankine Lecturer in 1987. He was also a
Guggenheim Fellow and a Churchill Fellow at Cambridge
University, England. In 1995 he received an Honorary Doctorate
of Engineering from his alma mater, the University of Glasgow.
Ron was the author of four books, over 250 papers, and holds
four United States patents.
He leaves behind his wife Pamela J. Scott, his sons Grant
Fraser Scott, Craig Alistair Scott, Roderick Jonathan Scott, and
nine grandchildren.
BY PAMELA J. SCOTT
SUBMITTED BY THE NAE HOME SECRETARY
Ron was a kind, thoughtful and loving husband and father
to our three sons. Although he was extremely busy with his
work at Caltech and his involvement with the space program
in the 1960s, he always made time to spend with his three
small boys.
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256 MEMORIAL TRIBUTES
Ron was a very keen and competent golfer. He taught the
boys golf at an early age, and Grant especially enjoyed playing
with his father, with the junior PGA and on his high school
team. I also took up the sport although I preferred tennis. We
made a pact shortly after our marriage that I would learn to
play golf if he would take tennis lessons. Consequently,
throughout the years when the boys were home, we would all
play tennis and golf together.
Ron was proud of their athletic prowess and would
enthusiastically watch their high school games: Grant tennis,
soccer, and golf, and Craig and Rod soccer, swimming, and
water polo. Craig and Rod were Eagle Scouts with the honor
of carrying the banner in the 1979 Rose Bowl Parade when
Jimmy Stewart was the Grand Marshal. We all loved to hike
and we spent many happy hours in the local mountains and
national parks and also hiked and camped in Europe and
Hawaii.
We all love to read and it was Ron who instilled a love of
books and reading in our lives. To quote Grant’s remarks at the
memorial gathering, “My father cultivated a love of literature
and was an omnivorous reader . . . he loved words especially
puns where there was slippage in the slope of language, perhaps
a kind of liquefaction where two letters supporting a dam of
meaning gave way or there was semantic friction or failure. He
liked to see words collapse into other words and watch as a
seismic shift altered the landscape of a sentence.”
Ron was not only a husband and father but our best friend,
always approachable with advice, guidance, and a marvelous
sense of humor.
Acknowledgment
Paul C. Jennings wishes to acknowledge that some of the
information and quotations in this tribute are taken from articles
in Engineering & Science, published by the California Institute
of Technology.
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