Geosynthetics February/March 2020 - 28

U.S. Bank Stadium geosynthetic reinforced stress relief wall

FIGURES 7 and 8 Fire damage: Melted geotextile and geogrid at RSS face

FIGURES 9 and 10 Fire damage remediation: Reinforced shotcrete facing with shallow
percussion-driven anchors

damaged. The authors observed the
damage within a few hours of the fire.
The polypropylene woven geotextile
face wrap and the polyester geogrid
reinforcement that wrapped around the
face had melted over a 30-foot (9.1-m)
horizontal distance and over the full
30-foot (9.1-m) height of the RSS wall.
The granular fill was starting to slowly
slough out at the face in the damaged
portion of the RSS. The Material Safety
28

Geosynthetics | February March 2020

Sheets identified that the geotextile
polypropylene fiber melts at approximately 325oF (163oC), while the polyester geogrid melts at 400 oF (204 oC).
These temperatures were apparently
exceeded near the RSS face during the
fire, since both products had melted to
some degree. Figures 7 and 8 show the
RSS fire-damaged facing.
Geogrid samples were cut out of the
fire-damaged portion of the RSS at various distances back into the fill from the
face to determine the extent back into
the RSS the geogrid reinforcement had
been compromised. The forensic ASTM
D6637 testing indicated that the geogrid
reinforcement was only damaged within
approximately 1 foot (0.9 m) of the RSS
face. Based on these test results, it was
determined that remediation would only
be required at the RSS face and that
complete excavation and reconstruction
of the RSS within the fire-damaged area
was not necessary.
The facing remediation plan selected
consisted of placing a new welded wire
mesh on the face, shotcreting the face,
and then installing a series of 3-to-5-feet
(0.9-to-1.5-m) long Gripple percussion
driven anchors within the fire-damaged
area. The anchors were installed at a
3-foot (0.9-m) triangular spacing. The
remediation measure was designed
assuming that the outer 3 feet (0.9 m)
of the geogrid and the geotextile wrap
had been compromised.
The anchors and shotcrete were
installed from a swing stage by a construction crew that was experienced
in confined space concrete work. Two
3-inch (7.6-cm) thick layers of shotcrete, reinforced with W4.0 × W4.0
welded wire mesh, was applied over the
damaged RSS face. The design required
that the percussion-driven anchors be
installed with a hammer drill after shotcrete installation. Anchor proof testing indicated that all anchors exceeded



Geosynthetics February/March 2020

Table of Contents for the Digital Edition of Geosynthetics February/March 2020

Geosynthetics February/March 2020 - Cover1
Geosynthetics February/March 2020 - Cover2
Geosynthetics February/March 2020 - 1
Geosynthetics February/March 2020 - 2
Geosynthetics February/March 2020 - 3
Geosynthetics February/March 2020 - 4
Geosynthetics February/March 2020 - 5
Geosynthetics February/March 2020 - 6
Geosynthetics February/March 2020 - 7
Geosynthetics February/March 2020 - 8
Geosynthetics February/March 2020 - 9
Geosynthetics February/March 2020 - 10
Geosynthetics February/March 2020 - 11
Geosynthetics February/March 2020 - 12
Geosynthetics February/March 2020 - 13
Geosynthetics February/March 2020 - 14
Geosynthetics February/March 2020 - 15
Geosynthetics February/March 2020 - 16
Geosynthetics February/March 2020 - 17
Geosynthetics February/March 2020 - 18
Geosynthetics February/March 2020 - 19
Geosynthetics February/March 2020 - 20
Geosynthetics February/March 2020 - 21
Geosynthetics February/March 2020 - 22
Geosynthetics February/March 2020 - 23
Geosynthetics February/March 2020 - 24
Geosynthetics February/March 2020 - 25
Geosynthetics February/March 2020 - 26
Geosynthetics February/March 2020 - 27
Geosynthetics February/March 2020 - 28
Geosynthetics February/March 2020 - 29
Geosynthetics February/March 2020 - 30
Geosynthetics February/March 2020 - 31
Geosynthetics February/March 2020 - 32
Geosynthetics February/March 2020 - 33
Geosynthetics February/March 2020 - 34
Geosynthetics February/March 2020 - 35
Geosynthetics February/March 2020 - 36
Geosynthetics February/March 2020 - 37
Geosynthetics February/March 2020 - 38
Geosynthetics February/March 2020 - 39
Geosynthetics February/March 2020 - 40
Geosynthetics February/March 2020 - 41
Geosynthetics February/March 2020 - 42
Geosynthetics February/March 2020 - 43
Geosynthetics February/March 2020 - 44
Geosynthetics February/March 2020 - 45
Geosynthetics February/March 2020 - 46
Geosynthetics February/March 2020 - 47
Geosynthetics February/March 2020 - 48
Geosynthetics February/March 2020 - 49
Geosynthetics February/March 2020 - 50
Geosynthetics February/March 2020 - 51
Geosynthetics February/March 2020 - 52
Geosynthetics February/March 2020 - Cover3
Geosynthetics February/March 2020 - Cover4
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-february-march-2024
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-december-2023-january-2024
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https://www.nxtbook.com/ata/geosynthetics/geosynthetics-april-may-2023
https://www.nxtbook.com/ata/geosynthetics/geosynthetics-february-march-2023
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https://www.nxtbook.com/ata/geosynthetics/geosynthetics-october-november-2022
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