Geogrid For Retaining Walls
Geogrid is a vital component in all types of hardscape, including retaining walls. It increases stability and prevents shifting and settling.
As a result, it is necessary for retaining wall projects with taller walls. To determine the length, vertical spacing and number of layers needed, consult a qualified professional civil engineer with segmental retaining wall design experience.
Uniaxial
When it comes to soil reinforcement and stabilization, geogrids are the gold standard. They’re commonly used in construction projects due to their versatility and effectiveness. They’re capable of transferring loads from the backfill to the soil and helping reduce the stress on the wall, making them a vital component of any retaining wall project.
There are several different types of geogrid available for use in retaining walls, including uniaxial, biaxial, and triaxial. Uniaxial geogrids offer greater control of movement in one direction, which makes them a great choice for retaining walls. Biaxial and triaxial geogrids are both stronger in two directions, which is useful for retaining walls that will have a large amount of pressure on them.
Geogrids are made from a variety of materials, such as polypropylene (PP) and polyethylene (PE). They’re lightweight, durable, and provide excellent resistance to UV radiation, chemicals, biological degradation, and other environmental factors. They’re also easy to install, reducing labour and equipment costs.
Before you begin your retaining wall project, you should decide which type of geogrid is the best fit for your needs. It’s important to note that you should always consult your design engineer for the final wall details and recommendations. When deciding on the length of the geogrid you’ll need for your project, you should consider the height of your wall and whether or not a drainage blanket will be required.
Triaxial
While the most common use of geogrid is as reinforcement for retaining walls, it can also be used in high-pressure locations such as footings and roadways. In these applications, a geogrid for retaining walls triaxial geogrid can be laid to distribute the point load over a larger area which reduces movement and settlement of the soils under the footings or roadways.
Geogrids allow the underlying earth to interlock with the apertures on the grid, creating confinement and keeping materials in place, even during an earthquake. This can reduce the amount of material that must be placed behind the retaining wall and save on construction costs, especially for taller walls.
Uniaxial geogrids are best for retaining walls that are more than 6 ft. tall because they have a strength in one direction, which helps them resist pressure on the top of the retaining wall. They should be rolled out perpendicular to the wall in lengths that are dictated by a certified engineer based on the height of the wall, conditions of the soil and subgrade, and the load the wall is designed to support.
When laying a uniaxial geogrid, make sure it covers the entire hole and slot in each block of the VERSA-LOK system and that the geogrid overlapping is covered by soil fill to avoid slick surfaces that can cause the blocks to slip or slide. Follow the specific layout instructions in VERSA-LOK Technical Bulletin #3 for curves and corners and always consult with your final wall design (P.E. stamped plans) engineer for any needed details and recommendations.
Biaxial
Biaxial geogrids are a great choice for retaining walls because they provide both tensile and shear strength. A biaxial grid’s tensile strength is determined by the Landfill Bentonite Waterproof Blanket size of its aperture (the opening size of its net-like voids). Its shear strength is determined by the junction efficiency, which is the strength of the cross section of the ribs, called nodes.
Bidirectional tensile and shear strength of the grid help to distribute the heavy load that is transferred into the soil. This reduces differential stresses that could compromise the integrity of the retaining wall and foundation.
The tensile and shear strength of a geogrid also helps to resist the damage that can be caused by rubber-tired or tracked equipment. This helps to protect the retaining wall system from damage, and it reduces the need for reinstallation of the geogrid.
Regardless of the type of retaining wall being built, the installation and placement of VERSA-LOK geogrid must be completed in accordance with the final retaining wall design and specifications prepared by a licensed professional engineer (P.E.). This includes preparing the site by placing VERSA-LOK units, backfilling and properly compacting soil fill and drainage aggregate to the height of the first (lowest) soil-reinforcement layer specified on the P.E. stamped construction drawings.
The proper installation of a geogrid layer will depend on the specific conditions of the wall and soil. To ensure maximum benefit, the geogrid should be installed in a manner that provides proper strain compatibility with the surrounding soil to avoid excessive deformation and maintain stability. For uniaxial geogrid, this means laying it out perpendicular to the wall. For biaxial geogrid, this means overlapping the layers with at least three inches of soil fill between overlapping pieces of the grid.
Large Roll
The large roll of geogrid is ideal for commercial and residential retaining walls up to 6 ft. tall. Designed to be stronger along the roll or machine direction, it can be cut to the design length and is easy to install. It can be pinned like uniaxial or biaxial grids. It is important to check the manufacturer’s criteria for correct orientation as it may be rolled in either direction.
Uniaxial and biaxial geogrid retaining wall mesh are both highly popular with contractors, homeowners, and municipalities for their durability and effectiveness in stabilizing soil behind structural retaining walls. Each type offers unique benefits that have been tested and proven for use in the field.
To get started with a project, the site needs to be excavated and prepared in accordance with the final wall design and specifications provided by a professional engineer (P.E). Typically, this includes building a retaining wall base and backfilling with soil fill and drainage aggregate up to the first layer of the geogrid-reinforced soil.
Once the retaining wall base and backfill have been placed, it is time to start placing layers of geogrid. Each layer of grid is pinned with steel pins. It is important to always leave a minimum of six inches of reinforcing soil backfill cover over the grid. Avoid driving or turning rubber-tired equipment directly over the geogrid, as this can cause excessive damage.
