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The repaired sloped blends into the natural surroundings of the area
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| PRODUCTS: |
TENAX TT mono-oriented geogrids |
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Location:
Boscaccia, Sondrio, Italy
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Owner:
Office of Public Works Lombardy Region |
Project:
Dr. Ing. Del Simone, Dr. Azzola
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Engineer:
PAC SpA, Capo di Ponte (BS) |
Problem
In July of 1987, following heavy rainfall and exceptionally
large quantities of melting snow, the Adda river disastrously
overflowed leading to both floods and the bursting of river
banks.
The rain and floods also led to numerous landslides
through the Valtellina valley. One such landslide occurred
in Boscaccia, in the municipality of Sondalo, in the province
of Sondrio.
The landslide in question involved gravely sandy
soil which formed part of an alluvial cone; the total volume
of the landslip was approximately 1.1 million cubic meters
and the total height of the slope was approximately 50 meters.
The problem involved both the stabilisation of the slope and
the protection against erosion at the base of the slope: both
of these tasks to be carried out taking into account the great
scenic and tourist value of the area.
Solution
The erosion protection at the base of the slope was achieved
through the construction of a reef of large boulders extending
160 meters, and a reinforcing wall allowing the passage of
water.
In addition to the drainage trenches, the slope was
stabilised by constructing 5 large terraces, each measuring
4 metres in height, 12.5 metres in depth and 130 metres in
length, which were reinforced with TENAX TT 400 geogrid. |
Landslide caused by heavy rain and flooding of the river
The failed slope is repaired with TENAX geogrids
Establishment of grass growth
Conclusions
The construction of earth terraces reinforced with TENAX TT400
geogrids allowed:
- The construction of a 25 m high geogrid reinforced structure
for stabilising the slope providing an overall slope safety
factor of 1.9.
- The greatest simplicity in setting up the structure by
re-using and improving the soil located on the site. During
the project a team of 4 workers installed 33,000 m2 of geogrids in 60 days.
- The creation of a 1:1 gradient terraced slope which is
completely stable and grassed, achieving the maximum protection
of the area's scenic attraction.
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Geosynthetics 
