Page 15 - Geotechnical Engineering Soil and Foundation Principles and Practice

Introduction
10 Geotechnical Engineering

In 1911 a Swedish scientist, Atterberg, by observing the properties of soils being
molded in the hands, suggested two simple tests to determine upper and lower
limiting moisture contents through which a soil exhibits the properties of a plastic
solid. These tests for the ‘‘liquid limit’’ and ‘‘plastic limit,’’ respectively, now form
the basis for most engineering classification systems of soils.

1.12 MARSTON’S EXPERIMENTS

In the early 1900s at Iowa State College (now University), Anson Marston began
full-scale studies of soil loads on pipes in ditches. He later extended the studies to
include soil loads on culverts under soil embankments, which can result in a many-
fold increase in vertical pressure on the pipe. Marston’s work was extended by
Spangler to include the response of flexible culvert pipes to these kinds of loads.

Marston’s research perhaps is most notable because he introduced full-scale
experimentation, and then attempted to explain the results from theoretical
considerations. Then, perhaps most importantly, he presented the results in a
simplified form that could be readily understood and used by practicing engineers.

1.13 TERZAGHI’S CONTRIBUTIONS

As a professor at Robert College in Turkey, Karl Terzaghi investigated a variety
of soil problems and proposed the term ‘‘Erdbaumechanik’’ (soil mechanics) in
1925. For this and subsequent contributions Terzaghi is considered the ‘‘father of
modern soil mechanics.’’
Terzaghi’s innovative concepts derive in part from his educational background
in both mechanical engineering and geology. His classical and widely used theory
to explain the time-rate of consolidation of saturated soils is an adaptation of
heat flow theory of thermodynamics. Terzaghi also proposed a theory for friction
in soils that is used in mechanical engineering for friction in bearings.

An important part of Terzaghi’s work was to verify his theories experimentally.
He devised and constructed the first consolidometer, a device that now is
commonplace in soil mechanics laboratories.

Again utilizing his background in mechanical engineering, Terzaghi proposed a
widely used theory for foundation bearing capacity that is an adaptation of
Prandtl’s theory for a metal punch. He then reduced complicated mathematical
relationships to a form that is readily understood and used by engineers. The
relation between a diversified background and creativity is the topic of a book
by Arthur Koestler (1964), who defined it as a ‘‘juxtaposition of conflicting
matrices.’’

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