Participating the seminar, from Freyssinet was Mr. Dimitri Plantier – Southeast Asian Regional Director of Reinforced Earth (a subsidiary company of Freyssinet Group) and his colleagues. For the host there were Mr. Nguyen Huu Chinh – Deputy General Director and leaders, engineers from relevant departments.
Mr. Nguyen Huu Chinh – Deputy General Director of EVNPECC1 addressed at the seminar
Opening the seminar, Mr. Nguyen Huu Chinh said presently the technology of Mechanically Stabillized Earth (MSE) wall has been applied and developed widely in the construction sector. EVNPECC1 keeps the leading firm in application of latest worldwide technologies in supporting, maintenance and new design at all power projects that the company is in charged. With the ambitions of sharing expertise and experience to design engineers in solving retaining wall design problem, he would like to welcome experts from Freyssinet group to participate in the seminar.
After that, Mr. Dimitri Plantier introduced briefly on Freyssinet Group. This is multi-nationed leading group in the soil, structure, and nuclear. In 2010, Reinforced Earth Viet Nam (RECO) was founded in Vietnam bringing technical solutions for the design of retaining walls, crossing and protection works.
Mr. Dimitri Plantier , Southeast Asian Regional Director of RECO introduced on Freyssinet Group
And then it was the introduction of MSE from Freyssinet. The technology is based on the creation of a composite material working on the principle of the friction between tightly-compacted granular materials with reinforced anchors. The soil reinforcement materials could be metal (high-strength acierate anchor) or composite fibre (composite polyester typed anchor).
The structure of MSE comprises of 3 major components:
- Concrete panels or wire mesh;
- Soil reinforcements or composite fibre;
- Backfill with standard gradation.
The concrete retaining walls are established from precasted concrete panels which are different from each other in terms of geometry, thickness, dimension as well as the application field.
MSE construction technology has revolutioned in the civil engineering and has been applied in a lot of works such as: erosion protection at river banks, coastal, inland roads (retaining walls for embankment roads, bridge abutments, vertical slopes, anti-noisy embankment roads), railways, tunnels and works in industry, civil engineering or military. Many structures are highly resistant to crashes, explosions, etc. This technology has also been widely used in hydraulic structures with advantages like high durability against conditions such as floods, tidal variations, storms, floods and other impacts.
Benefits of reinforced earth walls:
- High durability.
- Save cost, simple and fast construction.
- Friendly with the environment.
- Flexible with all types of topography.
- Cross the height span which the traditional reinforced concrete wall fails to satisfy.
- The slope for dykes can be vertical up to 90 degrees, and the height for this is up to 45-50m.
- Safety ensure.
- High aesthetic
Freyssinet Group introduced on Mechanically Stabilized Earth walls
Also at the seminar, Mr. Dimitri Plantier introduced the reinforced earth wall combining with Terralink. The Terralink technique allows the construction of reinforced earth walls in front of any existing structures, slopes or existing natual gravel, rock environments where there is a narrow construction space between them by effectively connecting the two structures together. It is an excellent solution where the site constraints, preventing construction in using other types of retaining walls.
There are two methods of connecting the reinforced earth wall to the existing structure or slope to form a shored retaining wall, either a direct connection, or a frictional link which incorporates soil reinforcement attached to the existing structure or slope which then overlap with the reinforcement from new structure, the overlaps between reinforcement layers ensure frictional connection on both sides of the structure.
Mr. Dimitri Plantier presented the construction sequences as well as shared projects using Terralink anchors, from which showed its advantages:
- Flexibility in design
- Reduces footprint at the base of the structure
- Reduced excavation works
- Reduced backfill
- Speed of construction
- Avoiding the need to demolish existing structures
- Minimal disruption to traffic flow
Introduction of reinforced earth wall combining with Terralink
The Reinforced earth wall under water is also a subject to be discussed there. The Reinforced earth technique has been extensively used for 40 years to build structures such as: highways and railways along rivers, lakes and waterways. Wide selection of the soil reinforced materials associated with Reinforced earth wall system allows this technique to be applied for all types of water conditions, freshwater, brackish water or saline water.
Experts from Freyssinet introduced on reinforced earth walls in water environment
Precast tunnel Techspan was also presented at the seminar.TechSpan is a three pin, two piece precast concrete arch system that enables the designer to create the most structurally efficient custom made shape to suit any particular clearance or loading condition. Funicular curves have infinite variations, but in each one the bending moment and tensile stresses at any point are theoretically zero for any given set of load conditions. Techspan arch design follows this same mathematical approach to create a custom made structurally efficient profile to suit each unique set of geometry and loading conditions.
Techspan is always designed to use the most economical concrete and reinforcement to minimize the amount of materials needed for production and transportation. Besides, this technology also helps reduce carbon emissions and transportation costs, and increases installation speed, durability and design life.
One of the main advantages of Techspan is the ease and rapid speed of construction. Once the initial four units are in place, only one crane is needed from thereon as each arch unit is supported by the arch unit previously placed. A concrete crown beam is then installed at the top of the arch structure, effectively locking the structure together as a robust concrete tunnel.
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Delegates at the seminar
Apart from the above mentioned presentation, some solutions for landslide were emphasized at the seminar. The Group has been involved in several projects in the world such as rehabilitation for the road D918 in France which was landslided in 2018 with its 250m2 reinforced earth walls, 3m backfill slope above; protection of Seydhisfjördhur village in Island from avalanche with 20m high reinforced earth barrier.
The seminar took place very excitingly with lots of Q&A coming from the guests and representatives of the parties to discuss the reinforced earth wall technology.
Discussion between guests and experts of Freyssinet Group
Closing the seminar, Mr. Nguyen Huu Chinh, on behalf of EVNPECC1 expressed his thankfulness to Freyssinet Group for its presentation, sharing experience and technology to the Company. He also thanked to delegates and guests for their attendance and contribution to the seminar’s success. He said after the seminar, hopefully the two enterprises could keep contact, exchange, share and establish long-term cooperation in the future.