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24-031
Engineering a Large Eco-Friendly Reinforced Sloped MSE Wall
System to Increase the Size of a Flat, Work Area of a Mine
Carlos Andrade
Maccaferri, Inc.
An engineering endeavor involves the creation of an expan-
sive, environmentally conscious reinforced sloped MSE
wall system. The objective is to enlarge a flat mining work
area. Situated in southern Arizona, this mine is dedicated
to extracting essential resources such as Manganese, zinc,
silver, and lead, crucial for advancing clean and renewable
energy initiatives. The project necessitates the implementa-
tion of a Mechanically Stabilized Earth retention system.
This system aims to both expand the mine’s working area
and facilitate access to underground tunnels.
The expansion pad must be robust enough to endure
the substantial loads exerted by heavy mining machin-
ery. The wall’s reinforcement components are strategically
designed to counteract the challenges posed by aggressive
soil conditions with low resistivity. Furthermore, they must
be resilient against potential damage during installation.
The system’s ease of transportation is crucial due to chal-
lenging access conditions, and its design must allow for
efficient drainage.
A significant consideration is the integration of a face
system that fosters vegetation growth and seamlessly merges
with the existing flora of the area. In addition, plans include
the construction of an access road downslope from the wall.
The chosen solution involves a reinforced sloped system
with a 70-degree incline. The wall’s surface is adorned with
an erosion control mat, intended to promote the prolifera-
tion of vegetation. For added durability, the wire basket
units are equipped with galvanized wire featuring a
polymer coating. High tensile strip bonded geogrids, featur-
ing a robust polyester core, provide essential reinforcement.
The completed wall is an impressive feat, spanning
1500 feet in length and soaring to a height of 45 feet. It
stands as a testament to innovative engineering in harmony
with environmental and functional considerations.
SELECTION OF GEOSYNTHETIC
REINFORCEMENT MATERIALS
The design parameters to be considered in the design of the
MSE wall structure included a horizonal and vertical peak
ground acceleration coefficients, CONEX Box Containers
Loading capacity, and in situ backfill selection of highly
corrosive soils.
A selection of Geogrid geosynthetics manufactured
from high tenacity, multifilament polyester yarns aligned
and co-extruded with polyethylene (LLDPE) to form
Polymeric strips. The heavy LLDPE coating enable the
Geogrid product to be used as reinforcement of contami-
nated and high aggressive materials for use in environmen-
tal applications. Different strengths of geogrid were used to
accommodate height levels and loading, below is a chart of
the products used:
Product Name Tensile Strength (Ultimate)
Paragrid 65/5 65 kN/m 4454 lb/ft
Paragrid 80/8 80 5482 lb/ft
Paragrid 100/5 100 kN/m 6852 lb/ft
Paragrid 120/5 120 kN/m 8222 lb/ft
SELECTION OF DRAINAGE COMPOSITE
MATERIALS
The large expansion pad area would be subject to collect
substantial amounts of rainfall, a proper drainage system
for the wall was a key factor for the proper functioning of
the MSE wall. A Geocomposite for planar drainage system
(GCD), was selected. It is realized by thermobonding a
draining core in extruded monofilaments (GMA) with two
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