When a large amphibious assault vehicle rolls up on a beach, it's bound to displace a fair amount of sand.

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Back in the 1970s, the U.S. military set about solving a long-standing problem in combat operations: the movement of the ground beneath heavy equipment. When tanks and supply trucks move around on unstable dirt and sand, especially on coastlines, displacement and erosion occur, which means even less stable ground to travel on.

The solution came in the form of a lightweight structure that held together loose sand, dirt or gravel so the ground stayed put. The trick was in the structure's honeycomb shape.

It's called cellular confinement, or geocells, and it's not just for the military. Products like EnviroGrid, one version of the geocell approach, have widespread civilian applications. Geocell technology holds together all sorts of ground structures, from flat land to 45-degree slopes and from arid ground to highly vegetated soil. It has applications in landscaping, civil engineering and environmental protection. You may have walked or driven on geocells without even knowing it.

In this article, we'll find out what cellular confinement does, how it's used and why it's better than some of the more common and traditional geological-stabilization techniques.

Most of us don't think much about geological stability, but it's a big issue in engineering and outdoor design. How do you build up a mound of dirt to make a hill on a golf course without it washing away in the first rain storm? How do you build a driveway on a base of mushy red clay? And how do you make sure the sloped sides of a highway don't wash out after 20 years of high winds?

You somehow secure all of these structures so they can bear weight and withstand the elements. Typically, this is done using concrete walls, or by layering geotextile fabric with compacted aggregate (like dirt and rocks), or building a raised bridge to bypass the problem entirely. EnviroGrid is an approach to accomplish the same end while working a bit more closely with the natural environment.