DFI Magazine November/December 2020 - 105

GUEST

EDITORIAL

Game (Advanced Geotechnical Methods) " On "
There is a challenge, and it's time that we,
within the foundation industry for
highways and other infrastructure, bring
our best effort to bear on it. Geotechnical
site characterization is a fundamental
starting point of nearly every infrastructure
project on, or in, the earth. Yet, for
something so important, geotechnical
professionals frequently spend an
incredibly small amount of effort obtaining
information on subsurface conditions.
Historically, it has been common that the
scope of our subsurface investigation work
- the information on which we base our
decisions - consists of sampling, sensing
or testing less than 0.1% of the materials
influencing our project space. No doubt,
we use our knowledge and experience to
inform our judgements, and there are
many cases where expectations of
conditions from such limited data prove
satisfactory. But there are enough times
when conditions are not entirely as
expected that this results in delays and cost
escalations. These moments are in no one's
legitimate interest, and it makes you think:
What's the real cost of these uncertainties?
And what's the cost of removing the large
majority of these unknowns?

It is a numbers game,
involving risk and reward; yet,
we frequently rely on our
routines and past practices
instead of considering different
strategies. In 2019, the Federal
Highway Administration
(FHWA) partnered with industry
to launch an effort that was intended partly
to remind ourselves that not all subsurface
investigations should solely or primarily
involve driving a split-spoon sampler with
a hammer. We have a very well-stocked
toolbox of subsurface investigation tools at
our disposal. The key is using the right
tools to do the job effectively. Effectively, in
this case, means understanding project
requirements and risks; thinking through
the necessary and valuable subsurface
information for successful planning,
design, construction and performance;
understanding the advantages and
limitations of specific exploration methods;
and optimizing the scope of subsurface
investigations to maximize the return on
investment. This FHWA effort is known as
Advanced Geotechnical Methods in
Exploration, or A-GaME for short.

Benjamin S. Rivers, P. E., senior
geotechnical engineer, Federal
Highway Administration

Relying so heavily on standard
penetration testing (SPT) in site
characterization practice, as many do, is
like a sport's team having one play in its
playbook. While A-GaME does not limit the
technologies used for site characterization,
the primary focus is on promoting five
technologies for routine and mainstream
practices. Many of these are wellestablished, yet underutilized, and all of
them are proven. These technologies are:
Cone penetration testing (CPT): CPT
provides continuous, directly measured,
digitally acquired soil resistance
measurements with depth, often at advance
rates 3 to 10 times faster than conventional
drilling, testing and sampling techniques.
Small strata changes are easily discernable
because measurements are acquired at a
comparatively high sample rate. Variants of
the CPT such as the CPTu and SCPTu
provide pore water pressure and shear
wave measurements as well. This allows for

LADOTD web application display of statistical data and layer stratification using DIGGS (credit: Jesse Rauser, LADOTD)

DEEP FOUNDATIONS * NOV/DEC 2020 * 105

DFI Magazine November/December 2020

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