Reinforced Earth
Reinforced Earth and Freyssisol, ideal for building land-based or submerged retaining structures, are widely used throughout the world: walls, bridge abutments, storage facilities, protective barriers, etc.
Principle
The principle is simple, thanks to the substantial developed frictional force between soil particles and reinforcements when they come into contact, the combination of suitably distributed reinforcements and loose backfill produces Reinforced Earth, a composite material with numerous benefits such as:
- High resistance to static and dynamic forces,
- Structures are flexible and therefore adapt well to deformations below ground,
- Installation is quick and simple, which offers substantial savings, in time and cost.
The reinforcements typically galvanized steel or synthetic notched sheets, are placed in horizontal layers which are approximately 80cm vertically apart.
The skin is made of prefabricated concrete panels separated by joints that provide the flexibility that is the key to the use of Reinforced Earth.
These panels are connected to the reinforcements and placed in staggering pattern. The staggering pattern ensures the continuity of the facing in the event of substantial settlement below ground and facilitates the erection of prefabricated panels.
The prefabricated concrete panels can sometimes be substituted by welded wire mesh panels.
Installation
The quick and easy assembly of Reinforced Earth structures can be considerably contributed to the fact that there is no need for any type of scaffolding or form work.. Each panel is placed between other already installed panels
The proper alignment of the facing is ensured by:
- wooden wedges installed on the outside of the facing between horizontal edges, which are removed later as the filling operation progresses,
- traditional clamps installed at the top of the panels.
In addition to the traditional earth-moving machinery equipments required to place the backfill, a light crane is required to move the panels, with weight ranging between 0.8 and 1.2 tonnes for standard panels with a thickness of 14 cm.
The backfill put in place as the installation of the panels progresses, in layers of a 35 to 40 cm thick, which corresponds to half the distance between two reinforcement layers.
The succeeding assembly operations are detailed briefly below. When carrying out assembly work or to obtain further and more detailed information, please refer to the detailed assembly instructions.
Unloading and storing the elements
The panels are transported and stored on a flat surface, with wood wedges (dunnage), placed between them to prevent any damage to the tie strip (connection insert embedded in prefabricated panels). The metalic reinforcements are delivered in maximum loads of 3 tonnes. The synthetic reinfor-cements are delivered in rolls of 100 m.
Installation of the panels, reinforcements and joints
The first row of panels is installed on an unrein-forced smooth finish concrete pad that is well-leveled to ensure a correct right positioning. This first row of panels is directly supported on the ground to prevent them from moving during the backfilling process.
The upper row panels are installed as the backfilling operation progresses. The plumpness is ensured by temporary wedges and clamps. Elastomer blocks are installed when the panels are placed (2 per panel), in between horizontal joints. The vertical and horizontal joints are then covered with bonded strips before the filling process takes place.
The reinforcement layers are spaced 70 to 80 cm apart, which corresponds to double the maximum thickness of the backfill layers. They are installed on the roughly leveled ground and bolted to the panels.
