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Geotechnical News December 2011
CGS NEWS
W. D. Liam Finn’s 2011 Legget Medal
Award Acceptance Speech
Mr. President, Geotechnical Colleagues
and Friends!
I am deeply honoured to have been
selected by the Canadian Geotechnical
Society (CGS) to receive their most
prestigious award, the R.F. Legget
Medal and I am very grateful to the so-
ciety for their consideration. My thanks
are also due to the selection commit-
tee and my nominees for thinking that
I might be a worthy candidate for con-
sideration.
This is a very happy occasion for me
and it is enhanced by the presence of
my wife, Tomris, whose affection, care
and understanding have been main-
stays of my professional and private
life. I just learned at this meeting that
my nominees were all my geotechnical
colleagues at the University of British
Columbia. I was deeply touched by
that. The appreciation of one’s peers
is deeply satisfying to a professional
engineer. Finally I must thank Adrian
Wightman of BGC Engineering, Van-
couver, for his introduction, especially
for how he presented it. By the end of
his presentation I began to like the guy
he was talking about. As a lifelong ana-
lyst, I know very well how idealization
improves a model!!
The CGS asked me to give a his-
torical overview of geotechnical engi-
neering and say a few words about the
future. Let me assure you that I do not
intend to deliver a historical lecture
between the main course of this lunch
and the dessert. But I will make a few
observations about my own more re-
stricted field, Geotechnical Earthquake
Engineering.
I was fortunate to be a visiting pro-
fessor at Berkeley in 1964 when the
Alaska and Niigata earthquakes oc-
curred. The damage caused by lique-
faction was a dominant characteristic
of each earthquake. Professor Seed and
his graduate students (now Professor
Emeritus I. M. Idriss of UC Davis and
the late Professor Ken Lee of UCLA)
were studying these events and seeking
ways to evaluate liquefaction potential
and analyze the seismic response of
the ground. I quickly realized the op-
portunities of working in a field about
which little was known and switched
my research efforts from applications
of plasticity theory in Soil Mechanics
to what was then called Soil Dynam-
ics and later matured into Geotechni-
cal Earthquake Engineering (GEE). I
returned to UBC in 1966 and managed
to get NSERC to fund a soil dynamics
laboratory including the first geotech-
nical shake table to have full control
over the input motions. The table incor-
porated an MTS controller and MTS
devoted an issue of their trade maga-
zine to the UBC installation. Geotech-
nical earthquake engineering was on its
way in Canada.
In 1966 two papers appeared that
advanced the role of dynamic analysis:
a paper by Anil Chopra of Berkeley
on dams and a paper on slopes by me.
Both papers showed the power of finite
elements in the analysis of earth struc-
tures. My paper led to an invitation to
visit the Soviet Union in 1967 to assist
in the dynamic analysis of the analysis
of the largest rock fill dam in the world
planned for Soviet Georgia.
In the years up to 1973, the Berkeley
group laid the foundations of geotech-
nical earthquake engineering and raised
the capability of practicing engineers
to do dynamic analysis of earth struc-
tures by the development of the pro-
grams SHAKE, QUAD4 and FLUSH.
These programs were all based on the
brilliant insight of equivalent linear
analysis. On the laboratory front great
progress was made in understanding
the parameters that controlled liquefac-
tion potential but a gradual shift was
underway towards evaluating lique-
faction potential using in-situ testing
because of the difficulty of retrieving
representative samples of sand. This
initial period of development culmi-
nated in the analysis of the failure of
the Lower San Fernando Dam under
shaking from the 1971 San Fernando
earthquake. The analysis of this dam
exposed some limitations in the exist-
ing total stress methods of analysis and
set the stage for the development of ef-
fective stress dynamic analysis.
In 1975 the Martin-Finn–Seed (M-
F-S) porewater pressure generation
model was developed that made effec-
tive stress dynamic analysis possible.
This model was incorporated in the
UBC programs DESRA 1-D (1975)
and Tara-2D (1980). Later versions of
these programs are still in use today
and the M-F-S model is also available
in FLAC. By 1988 the attitude towards
treating liquefaction was changing
from removing the liquefaction threat
to dams by expensive ground improve-
ment to controlling the consequences
to ensure an acceptable performance
level. It was first applied to the reme-
diation of Sardis Dam in Mississippi
where performance criterion was to
limit crest settlement to 1.7m. To allow
the large displacement analysis of the
untreated dam in order to understand
the potential failure mechanism, TARA
was modified to a Lagrangian formula-
tion – the basis also of the FLAC pro-
gram. This was the advent of formal
performance based design in Geotech-
nical Earthquake Engineering.
FLAC has had a powerful influence
on engineering practice by facilitating
W.D. Liam Finn
