Geosynthetics February/March 2024 - 15

Improving the performance
of geosynthetic reinforced
SRW by design
By Dov Leshchinsky, Ora Leshchinsky and Ben A. Leshchinsky
G
enerally, using current design standards (e.g., any AASHTO edition),
geosynthetic reinforced segmental retaining walls (SRW) have performed
well. However, there exists scenarios that predispose such systems to poor
performance, particularly inadequate reinforcement within the wall system
and in the unreinforced backslope at its crest. When reinforcement spacing
is large, say, every three courses of stacked blocks (approximately 0.6 m or 24
inches), such walls might deform beyond tolerance or lose facing units. These
systems are commonly built with a backslope to reach a final design elevation
economically; however, such backslopes are not reinforced and their gradient
relative to the soil strength is quite steep (i.e., the backslope might be close to a
state of shallow failure). Failure initiating within a backslope may affect upper
blocks comprising the wall, requiring avoidable maintenance.
The stability of backslopes is particularly questionable during earthquake
loading, where shaking may damage the upper portion of the wall by moving
or dislodging the upper stacked blocks. This scenario is aggravated by a common
reality in which an experienced wall contractor builds a wall first, followed
by the site developer or contractor who constructs the broken backslope
as well as much of the retained soil to very different standards. The involvement
of multiple contractors may lead to inconsistent construction practices
(e.g., compaction, use of select fill) for the wall and the soil behind and on top
of the wall, leading to problems that could be avoidable with consistent and
appropriate design.
Economically improving the performance
Two potential issues were stated in the introduction: large reinforcement
spacing and a steep broken backslope. Improving wall performance for
both aspects is, at face value, simple. That is, using closely spaced reinforcements
and building taller reinforced walls would eliminate the need for
Dov and Ora Leshchinsky founded ADAMA
Engineering, Inc. in 1989. Dov has over
47 years of experience in geotechnical
engineering, for 32 years has served as a
professor of geotechnical engineering at the
University of Delaware, and is a Professor
Emeritus in the department of civil and
environmental engineering. Ora is an
emerita registered professional engineer
(PE) in the state of Delaware and has over 50
years of experience as a practicing engineer
and as a university instructor of basic courses
in engineering.
Ben Leshchinsky, Ph.D., P.E. is the Richardson
Chair and Professor at Oregon State
University. He is currently the president of
IGS-North America.
All figures courtesy of ADAMA Engineering.
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Geosynthetics February/March 2024

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