Geosynthetics August/September 2021 - 8

Q &
A
GMA TECHLINE
MODERATED BY
George R. Koerner
BLUFF REPAIR IN SEISMICALLY
ACTIVE ZONE
Q: I am doing a bluff repair on the West
Coast in a seismically active zone. Can
you direct me to where I can get some
design guidance?
A: The following references are excellent
in regard to your question.
National Concrete Masonry Association. (2009).
" Guidelines for the design and analysis of
mechanically stabilized earth (MSE) structures
subjected to earthquake loads. " Seismic Design of
Segmental Retaining Walls, TEK 15-09A.
Transportation Research Board. (2010). National
Cooperative Highway Research Program (NCHRP)
Report 611, Ch. 7: Retaining Walls, Seismic Analysis
and Design of MSE Structures, www.nap.edu.
Wartman, J., Randonel-Oviedo, E. A., and RodriquezMarek,
A. (2006). " Performance and analysis of
mechanically stabilized earth walls in the Tecomán,
Mexico earthquake. " Jour. of Performance of
Constructed Facilities, 20(3).
BRINGING GEOMEMBRANES INTO
EQUILIBRIUM WITH ATMOSPHERE
Q: Some ASTM test methods request that one
brings the specimens into equilibrium with
the atmosphere prior to the test (some of
them determine the conditions: 21±2ºC and
60±10% relative humidity). Considering that
we just produce polyethylene geomembranes,
and they are not significantly affected by
the relative humidity, do you have any
suggestions about how long the specimens
should be kept under those conditions?
A: You are correct, polyethylene
geomembranes are not affected by relative
humidity. Nor are most geosynthetics for
that matter. This is demonstrated in the
reference Baker, T., and Koerner, G. (2000).
" Recommended Atmosphere for Geotextile
Testing. " Geotechnical Fabric Report, 18(1), 16-
17. That said, temperature matters. One will
need to bring the geomembrane to 21±2ºC
prior to the test. This usually takes half an
hour in the lab and not the 40 hours prior to
the test that the method suggests. You need
to address this in your quality manual and
show support for the actions you take in your
manufacturing quality control (MQC) lab.
I can well imagine that your statistical process
control (SPC) data would be marginalized if
you had a 40-hour time lag with production.
8
Geosynthetics | August September 2021
http://www.nap.edu

Geosynthetics August/September 2021

Table of Contents for the Digital Edition of Geosynthetics August/September 2021

Geosynthetics August/September 2021 - Cover1
Geosynthetics August/September 2021 - Cover2
Geosynthetics August/September 2021 - 1
Geosynthetics August/September 2021 - 2
Geosynthetics August/September 2021 - 3
Geosynthetics August/September 2021 - 4
Geosynthetics August/September 2021 - 5
Geosynthetics August/September 2021 - 6
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Geosynthetics August/September 2021 - 8
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Geosynthetics August/September 2021 - Cover3
Geosynthetics August/September 2021 - Cover4
Geosynthetics August/September 2021 - GeoNashville Attendee Brochure 1
Geosynthetics August/September 2021 - GeoNashville Attendee Brochure 2
Geosynthetics August/September 2021 - GeoNashville Attendee Brochure 3
Geosynthetics August/September 2021 - GeoNashville Attendee Brochure 4
Geosynthetics August/September 2021 - GeoNashville Attendee Brochure 5
Geosynthetics August/September 2021 - GeoNashville Attendee Brochure 6
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