Terramesh system – Reinforced soil retaining structure
The Terramesh system is one of the systems used in the construction of reinforced soil retaining structures. Reinforced soil retaining structures are executed by combining the embankment behind the front side of the retaining structure with tensile elements such as geomesh, hexagonal mesh, traps, etc. This type of structure is stable thanks to the interaction of tensile elements and the surrounding backfilled soil. The front side of the structure serves an aesthetic purpose and prevents local erosion, but does not significantly contribute to the overall stability of the structure as a whole.
Characteristics of the Terramesh system
The Terramesh system was developed by the Italian corporation Officina Maccaferri S.p.A. The system consists of gabion baskets with extensions. The gabion baskets are made of elements built using hexagonal mesh made of galvanized plastic wire 2.70 mm in diameter. The system makes the construction of a retaining structure with a very steep frontal inclination up to 70˚ possible.
Terramesh system execution
The front and upper sides of the gabion basket are folded during production, while all the other sides are built using special pieces of mesh that are fixed to the panel. An additional special panel serves as an extension and is fixed at the factory or construction site to the front and back side of basket at every 1.0 m of total length.
System elements are produced in standard dimensions: 2.0 m wide, 3.0, 4.0, and 5.0 m long and 0.5 and 1.0 m high. If necessary, other dimensions can be produced according to project requirements.
The execution of the gabion retaining structure with extensions is initiated after the excavation is finished. The first row of galvanized wire baskets and extensions is installed in such a way that the baskets (plan dimensions 2.0 x 1.0 m) are placed on the foundation so that the longer side is parallel to the excavation slope. The crushed stone is placed into the baskets manually and using a machine, with larger pieces stacked at the bottom, while the rest is filled with evenly sized stone. At 1/3 of total gabion basket height, the front and back side faces are connected with a galvanized wire of 3.0 mm in diameter to prevent deformation under the weight of the top baskets. When the gabion basket is completely filled, before closing it, the last 5.0 cm is filled with a stone aggregate 32.0 to 64.0 mm in diameter, which is evened out and which forms the flat surface required for the next row of gabions.
After the first row of gabions is completed, the space between the gabion basket and the face of the excavation is filled and the next row is started. The backfilling is executed in layers no thicker than 30.0 cm, and each backfill is compacted at full width by suitable compaction means. In order to increase the stability of the entire retaining structure, the second row of gabions is moved 33.0-50.0 cm inwards. After placing the second row, the baskets are attached to the first row and the stone placing process is repeated.
The gabion baskets with extension installment scheme is shown below.
Terramesh system application
We made the main retaining structure design for the construction of a parking lot along the state road D66 in Plomin. The selected solution used gabion baskets with extension with the following characteristics:
– Gabion basket width: 1.0 m
– Gabion basket length: 2.0 m
– Gabion basket height: 1.0 m
– Construction: Gabion basket with extension (Terramesh system)
– Extension length of the front side of the wall: Lp = 4,0 m
– Extension length from the rear side of the wall: Lz = 3.0 m
The normal cross-section of the executed retaining structure is shown below.
Conclusion
The construction of retaining structures using Terramesh systems and other reinforced soil systems has significant advantages:
- Height of retaining structures made using reinforced soil can exceed 50.0 m.
- Possibility of filling with excavation material.
- Resistance to significant settlements and displacements (flexible structures).
- Possibility of greening the front side (aesthetically acceptable solution).
- Speed and ease of execution.
Given these advantages, we believe that this type of retaining structure will be increasingly used in the future.
Read more: Gabion wall
