Environmental Engineering Reference
In-Depth Information
vation or landfill type, and to guarantee then the
necessary angles for the streets and for the access
ramps, according to the legal regulations;
- elimination of spaces between the buildings,
thus achieving to have the same construction
in a smaller area, reducing the extension of the
retaining structures;
- Rotation of alignments of some streets and
adjoining blocks, to a parallel direction of the
one of the soil level curves, resulting in economi-
cal and well-integrated solutions, using to small
height retaining structures, with particular inci-
dence on n3 and n4 blocks ( Fig. 5 ) .
3.2 General descriptionof the retaining
structures
When designing the solutions for the different
retaining structures in all blocks, it has been con-
siderated, besides all aspects already focused, all
the conditionings, such as, geological and geo-
technical, topographic, economical and execution
issues (cenorgeo 2004), which led to the need
of using different solutions, namely gravity and
semi-gravity cyclopean concrete walls, reinforced
concrete walls, or nailed walls and soil nailing
slopes.
Therefore, in the cases where the landfills to
execute, in order to create the buildings or streets
platforms, had, for a significant extension, an
height higher than 4,5 m, it was chosen to execute
retaining structures of gravity cyclopean concrete
walls type or of semi-gravity walls type. in landfills
which had an height under 5,5 m the choice was to
execute reinforced “T” shaped concrete walls.
all these walls are founded made directly on the
compact tuffs. in order to take advantage of the soil
resistance, whenever possible, the semi-gravity type
walls was adopted with a lower section in cyclo-
pean concrete, with the concrete poured directly
onto the soil, and an upper section, corresponding
to the landfill height, with a cantilever of rein-
forced concrete ( Fig. 6 ).
Retaining structures with U-shaped section were
also designed in order to include the cases where
there was the need to guarantee the vertical inter-
val between three platforms at different levels and
reduced distance, making the execution of two par-
allels walls impossible. Therefore, the defined sec-
tions correspond, in general terms, to two parallel
reinforced concrete cantilevers based on a common
foundation element, in reinforced or cyclopean con-
crete ( Fig. 7 ) .
in cases of compact tuffs excavation where,
due to geometric or architectural reasons, it was
necessary to ensure a vertical excavation between
two platforms and the referring massif was located
under the level of the upper platform, it was
decided to execute nailed walls with the higher sec-
tion in “l”-shape, also in reinforced concrete, cor-
responding to the height where it was not possible
to pour the concrete directly against the excavation
face. The purpose of these walls was, in a way, to
cover and abut the excavation to execute, and, in
another way to guarantee an identical finish to the
one of the adjoining structures.
considering the importance of the excavation
slopes to execute, essentially the ones located in the
limit of the different blocks, characterized by its
height and gradient, either the future buildings con-
struction on the platforms to support and the spe-
cific characteristics of those formations, the chosen
option was a soil nailing slopes solution, with shot-
crete and nails, which, besides allowing an adequate
coating to abut and avoid the soil progressive dis-
aggregation, is also a light retaining structure, flex-
ible and economic, well integrated and that takes
the maximum advantage of the resistance from the
formations that will be excavated.
since most of the soil nailing slopes to execute
were very exposed, it was given a special concern
minimizing their visual impact thus assuring the
best landscape integration. Therefore, a color
addictive was added in the sprayed concrete sec-
ond layer, which final color was set in the execution
phase, for the linings' adequate framing with the
surrounding area.
4
Technical assisTance DURinG
eXecUTion Phase
Giving continuity to the work concerning the pre-
liminary and final design, and due to this work
specificity, it was considered relevant to assure the
follow-up and technical assistance to the execution
of the numerous retaining structures, proceeding this
way to the structures' adaptation and optimization.
Figure 5. View of the slope upper area, located in the
limit of the n4 block.
 
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