Mechanically stabilised earth walls are an increasingly common method of designing Interbloc+ into high strength retaining wall. This article explains what an MSE wall is.
Mechanically Stabilised Earth Walls
A Mechanically Stabilised Earth (MSE) retaining wall is a composite structure consisting of alternating layers of compacted backfill and soil reinforcement elements, fixed to a wall facing. The stability of the wall system is derived from the interaction between the backfill and soil reinforcements, involving friction and tension.
The wall facing is relatively thin, with the primary function of preventing erosion of the structural backfill. The result is a coherent gravity structure that is flexible and can carry a variety of heavy loads.
Basic components of a MSE wall
The properties and materials of the three major components can vary, and a mechanically stabilised earth engineer must choose the most efficient combination of construction materials based on the wall’s design criteria, such as wall height and service life.
Facing elements are modular precast concrete blocks. Soil reinforcements are typically geosynthetic, in the form of a short piece of mesh cast into the block during manufacturing. This is then connected to a longer piece of mesh installed during installation. All soil reinforcement options have unique characteristics for pullout and tensile capacity, corrosion, and durability.
Benefits of MSE Walls
- Flexibility to accommodate high differential settlement and several feet of total settlement
- Bearing pressure is distributed over a wide foundation area
- Extreme wall heights can be achieved
- Extreme loads can be carried (bridge abutment footings, cranes)
- High resistance to seismic ground movement and other dynamic forces
- Free-draining, due to granular backfill and open panel joints
- Form liners can customize the aesthetics
- Very versatile. Special design can allow for nearly any geometry
- Rapid, predictable, and repetitive construction
- Superior finished wall alignment
- Mechanical connection of soil reinforcements to facing units
Example of combined MSE and Vertical Reinforced Wall
From time to time a combined MSE and Vertical Reinforcement design approach will be taken. This approach allows the design to leverage the benefits of each system.
'Geomat' Blocks
To facilitate a MSE wall, special blocks need to be manufactured where a short piece (to be determined by the design engineer) of geosynthetic ‘fabric’ is cast into the block. This is connected to a longer piece during installation. These Interbloc and Stonebloc blocks are known as GEOMAT blocks.
Typically TENSAR RE580 is specified for use in Geomat blocks. This particular product has the strength and durability required for most Envirocon MSE structures. TENSAR is supplied by Geofrabrics. Click here for the specific product webpage.