Gabions

The gabion cage has been around for roughly 125 years. Its essentially a cage made of wire holding large rocks to make a barrier. More specifically, galvanized wire that is PVC coated to protect against the elements and add longevity. They come in a variety of shapes and sizes but the most commonly used are 2x1x1 meter or 4x1x1 meter. Meaning four meters long, by one meter high and one meter deep. Their wire is double twisted to insure the wire is tight and will hold the cage together. They require a small footprint to install and are ideal for extreme erosion projects or when flexibility is required. They are mainly installed during the winter months as it allows us the ability to sink the bottom layer into the ground to help prevent undermining and guarantee a solid foundation.

image used from www.markham.com.pg

 

They are shipped flat and are transported easily to a job site. They are built on site. Below-right: A worker is shown assembling a 4x1x1 meter gabion. They are assembled using a stainless steel clip similar to a staple. Shown bottom right is the "gun" used to clip them together.

Here we see gabion's built and ready for use.

The "gun" used to clip the cages together to make them strong and tight.

The major benefits is that they are free draining. This means they allow water and ground runoff to permeate (seep) through them. Used in conjunction with geo-cloth or filter cloth they can effectively stop soil and land mass from being pulled through the cage by flowing water. Unlike concrete or solid vertical structures (steel sheets), gabion's actually allow wave action to penetrate the basket (gabion cage). In doing so the forces of the wave are dissipated through the width of the cage opposed to undermining like on impenetrable structures. What this means is that the waves energy is dissipated, as a result the material moved by the wave (sand) is deposited and in some cases a beach can be created.

Above: An example of gabion's buried below expected water level to help protect undermining and increase stability of the upper layers. We can also see the top layer connected and ready to be filled.

 

 

Above: Several meters of gabion's installed against eroding bank. You can see two levels of gabion's emerging from the water. Below water line there is a third layer roughly 3 feet below water level. This why they need to be installed in the winter months.

For more examples of our gabion installations please visit our Images page.

Several other erosion techniques exist. Please visit our Other Erosion Protection page to learn about them.

   

Last updated : Tuesday, January 17, 2012

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