TM 5-818-8/AFJMAN 32-1030
CHAPTER 7
REINFORCED SOIL WALLS
7-1. Geotextile-Reinforced Soil Walls
c. The construction of geotextile-reinforced walls
in cut regions requires a wider excavation than
Soil, especially granular, is relatively strong under
conventional retaining walls.
compressive stresses. When reinforced, significant
d. Excavation behind the geotextile-reinforced
tensile stresses can be carried by the reinforce-
wall is restricted.
ment, resulting in a composite structure which
possesses wider margins of strength. This extra
7-4. Uses
strength means that steeper slopes can be built.
Geotextiles have been utilized in the construction
Geotextile-reinforced walls can be substantially
of reinforced soil walls since the early 1970's.
more economical to construct than conventional
Geotextile sheets are used to wrap compacted soil
walls. However, since geotextile application to
in layers producing a stable composite structure.
walls is relatively new, long term effects such as
Geotextile-reinforced soil walls somewhat resemble
creep, aging, and durability are not known based
the popular sandbag walls which have been used
on actual experience. Therefore, a short life, seri-
for some decades. However, geotextile- reinforced
ous consequences of failure, or high repair or
walls can be constructed to significant height
replacement costs could offset a lower first cost.
because of the geotextile's higher strength and a
Serious consideration should be given before utili-
simple mechanized construction procedure.
z a t i o n in critical structures. Applications of
geotextile-reinforced walls range from construction
7-2. Advantages of Geotextile-Reinforced
of temporary road embankments to permanent
Walls
structures remedying slide problems and widening,
Some advantages of geotextile-reinforced walls
highways effectively. Such walls can be con-
over conventional concrete walls are the following:
structed as noise barriers or even as abutments for
a. They are economical.
secondary bridges. Because of their flexibility,
b. Construction usually is easy and rapid. It
these walls can be constructed in areas where poor
does not require skilled labor or specialized equip-
foundation material exists or areas susceptible to
ment. Many of the components are prefabricated
earthquake activity.
allowing relatively quick construction.
c. Regardless of the height or length of the wall,
7-5. General Considerations
support of the structure is not required during
a. The wall face may be vertical or inclined.
construction as for conventional retaining walls.
This can be because of structural reasons (internal
d. They are relatively flexible and can tolerate
stability), ease of construction, or architectural
large lateral deformations and large differential
purposes. All geotextiles are equally spaced so that
vertical settlements. The flexibility of geotextile-
construction is simplified. All geotextile sheets,
reinforced walls allows the use of a lower factor of
except perhaps for the lowest one, usually extend
safety for bearing capacity design than for conven-
to the same vertical plane.
tional more rigid structures.
e. They are potentially better suited for earth-
quite rapidly. At the end of construction, a protec-
quake loading because of the flexibility and inher-
tive coating should be applied to the exposed face
ent energy absorption capacity of the coherent
of the wall. An application of 0.25 gallon per
earth mass.
square yard of CSS-1 emulsified asphalt or spray-
7-3. Disadvantages of Geotextile-Reinforced
ing with a low viscosity water-cement mixture is
Walls
recommended. This cement mixture bonds well
and provides satisfactory protection even for
Some disadvantages of geotextile-reinforced walls
smooth geotextiles. To protect the face of the wall
over conventional concrete walls are the following:
from vandalism, a 3-inch layer of gunnite can be
a. Some decrease in geotextile strength may
applied. This can be done by projecting concrete
occur because of possible damage during construc-
over a reinforcing mesh manufactured from No. 12
tion.
wires, spaced 2 inches in each direction, supported
b. Some decrease in geotextile strength may
by No. 3 rebars inserted between geotextile layers
occur with time at constant load and soil tempera-
to a depth of 3 feet.
ture.
7-l
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