Today, we go below the surface. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.
Last Friday, coming back from
lunch, I noticed my civil-engineering colleague
Mike O'Neill walking fifty feet ahead of me. I
thought about hailing him, judged the distance to
be a tad awkward, and let it go. After all, we ran
into one another all the time.
Thirty-three hours later, Mike died of a heart
attack, and the opportunity was gone for good. I'll
try to keep that in mind the next time I fail to
greet a friend.
Watching him last week, one would have very little
sense that this was the great world expert on
building foundations. But things are not always
what they seem.
Mike fully recognized just how much the soil below
our buildings changes when it assumes the burden of
the structure above. Bury a deep piling in soil
whose properties you think you know, and that soil
is altered. A piling or foundation pier is invasive
in unexpected ways, because soil is perplexing
stuff. It's terribly variable -- never entirely
mineral. It generally has significant water mixed
in with it and even a certain amount of gas -- air
or products of organic decay. There is no recipe
for soil.
To support a piling, soil exerts a drag (or
shear) force upon it, and it is deformed
in the process. Think about walking on a wet sandy
beach. You've stepped on wet sand and seen it
dry out around your
footprint. That's because its volume increases
when you stress it. Water flows into the empty
space and the surface dries out.
Similar unexpected things happen when you set any
foundation in soil. The volume of the soil can
either increase or decrease. The result is that
pilings affect one another. Four foundation piers
can often give less than four times as much support
as a single pier. And the pattern of the pilings is
crucial.
These are the things that Mike O'Neill knew as much
about as any person living. He perceived the reach
of the problem fairly early in his long career, and
he constructed a mode of study that went all the
way from pencil-and-paper theory to full-scale
testing. And here lies another odd wrinkle in
Mike's story.
Many engineering problems can be solved with
intelligent modeling. We'd never have built jet
planes without scaled-down wind tunnel studies, but
soil introduces too many variables. So Mike became
one of the few engineering theorists I know who's
also famous for full-size testing of anything as
large as a building pier.
So buildings stand, today and tomorrow, while
foundations are set on slippery soil. And Mike
O'Neill built from the foundation of his own good
will. I'd offer that as a metaphor, but metaphors
weren't his style. He liked solidity and left the
fuzzy stuff to others.
That's why I was caught off guard as I walked by
his office this morning. Before it was a rising
heap of colleagues' flowers and cards. Never mind
metaphors, just let me add my own figurative rose
to that wonderfully telling heap.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
See, e.g., M. W. O'Neill, Side Resistance in Piles
and Drilled Shafts, Journal of Geotechnical and
Geoenvironmental Engineering, ASCE, Vol. 127,
No.1, January 2001, pp. 3-16. My thanks to Michael W.
O'Neill's civil engineering colleagues at UH, C.
Vipulanandan, Dennis Clifford, and Todd Helwig, for
their counsel.
For more on soil, see Episode
1601, on Dirt.
For more on the world underground, see Episode 850, Underground.
Michael W. O'Neill, 1940-2003.
The Engines of Our Ingenuity is
Copyright © 1988-2003 by John H.
Lienhard.
