DFI Magazine November/December 2020 - 106

additional characterization of groundwater
conditions and soil layers. Using CPT to
estimate soil properties, parameters and
behavior is more reliable and reproducible
than estimating those from SPT.
Electrical geophysical methods: Electrical
Resistivity (ER) can identify stratigraphic
boundaries and anomalies within
subsurface profiles over large areas
relatively quickly. ER is particularly useful
at distinguishing materials having
dissimilar conductivity, making it useful in
identifying clay, voids and water-bearing
layers. Other electrical methods such as
induced polarization (IP) and self-potential
(SP) are particularly useful in identifying
variations due to mineralogy, groundwater
conditions and groundwater flow. Thus,
the use of electrical methods, in
conjunction with CPTu, can greatly
improve site groundwater characterization
efforts needed to reduce the related claims,
change orders and overruns identified in
the National Cooperative Highway Research
Program (NCHRP) Synthesis 484
(Transportation Research Board, 2016).
Seismic geophysical methods: Seismic
methods provide direct measurements of
very small strain soil properties, which are
useful for understanding load-displacement
behavior, seismic hazard susceptibility and
seismic soil-substructure interaction
modelling. These methods also indicate
stratigraphic changes, boundaries and
anomalies within subsurface profiles over
large areas.
When used in conjunction with pointspecific in situ test data at various depths,
stratigraphy changes between pointspecific in situ testing locations can be
more accurately inferred, and confirmed,
as necessary. That confirmation involves
additional strategically placed in situ tests,
resulting in greater certainty of subsurface
models and the degree of variability. Like
electrical methods, these methods are
comparatively noninvasive and can be
conducted with equipment that is much
smaller than typical soil boring rigs for
areas where access is challenging.
Optical and Acoustic Televiewers:
Televiewers provide high-resolution,
spatially oriented and GIS-referenced core

106 * DEEP FOUNDATIONS * NOV/DEC 2020

hole images that have replaced difficult
oriented-coring in rock. Televiewer images
offer a superior means to visualize and
identify discontinuities based on complete
radial camera and/or ultrasonic imaging of
borehole sidewalls. Televiewers are
especially useful when the condition and
orientation of rock discontinuities are critical
to design, construction and performance,
and when quality core samples are difficult
to obtain from drilling operations.
Measurement While Drilling (MWD):
M W D p ro v i d e s a c o n t i n u o u s a n d
quantitative drilling record during the
drilling process. Measured parameters
include effective downthrust on the drill bit,
rotational speed, drilling fluid pressure,
torque, penetration depth and drill speed.
Relationships between multiple measured
drilling parameters have been established
and are useful in identifying strata changes,
material variations and anomalies, particularly within soil and rock too hard for CPT.
Recent work from Florida DOT and the
University of Florida shows that correlations
between drilling resistance and engineering
parameters can be effectively established.
MWD is standardized for geotechnical
practice in Europe (ISO 22476-15). MWD
practices are already common in the U.S. for
monitoring and quality control in ground
improvement applications and for augercast piling installation.
In addition to these highlighted
technologies, the A-GaME embraces the
idea of quantifying variation, by statistical
means, to better assess site variability. The
FHWA's Geotechnical Circular No. 5 on
Geotechnical Site Characterization introduces how the statistics from measurements and derived parameters can be
applied to the selection of engineering
properties within reliability-based design
(2017). This might sound onerous, but
there is now a new tool to make this process
much more automated than would have
been possible previously: the XML protocol
DIGGS.
DIGGS - www.geoinstitute.org/
special-projects/diggs - an acronym for
Digital Interchange for Geotechnical and
Geoenvironmental Specialists, is a real
game changer that will revolutionize our

industry. As discussed in a May/June
feature in Deep Foundations magazine,
DIGGS is a standardized digital data
transfer schema. The schema uses XML
grammar to encode geospatial information,
which profoundly improves workflow
efficiencies and deliverables for project
development, delivery, contracting and
acceptance. That is, DIGGS makes the dataexchange steps nearly seamless between
data-acquisition, data sharing, automated
programming, visualization, interpretation
and analysis, reporting, design, bidpackage preparation, construction and
performance monitoring. The use of
DIGGS in geotechnical practice was
standardized in July as AASHTO PP 102.
One commonality among all of the
A-GaME technologies is that they are
digitally acquired, making manual entry
unnecessary. After acquiring and processing
the raw data, processes can now be
efficiently automated by using the common
language that DIGGS offers practitioners.
Now, processes involving presentation,
reporting and visualization can be made
easy through effective programming, like
the DIGGS-ready web application for
interactive data visualization and interpretation recently developed by the
Louisiana Department of Transportation
and Development (LADOTD). Assessment
of site spatial variability can be clearly
conveyed with technologies like augmented
reality and 3D/4D (temporal) visualization.
New, and game-changing, tools like these
are improving the efficiency and effectiveness of communication of subsurface
site conditions among technical and
nontechnical stakeholders.
Greater use of newer field techniques is
only the start. As these systems become
more broadly implemented, additional
benefits will follow, ranging from improved
measurements to statistically derived riskbased design improvements and more
efficient information processing, visualization and use. These benefits can be realized
for today's projects as well as tomorrow's.
Instead of basing our decisions on a limited
playbook, it's time to bring our A-GaME.

http://www.geoinstitute.org/special-projects/diggs

DFI Magazine November/December 2020

Table of Contents for the Digital Edition of DFI Magazine November/December 2020