While it's natural to perceive the ground as a solid piece of earth, in reality, it can be quite unstable, especially under certain conditions. Before land deemed unstable can be used, it must be stabilized. Here is a look at this issue and how it is fixed.
When Do Civil Engineers Decide A Soil Must Be Stabilized?
Every major structural building project requires a team of professional engineers to oversee the project. Projects such as interstate highways, roadways, bridges, pipelines, subterranean sewer systems, and tunnels are massive construction undertakings that permanently change the landscape. Changes to the physical and environmental world required to build the infrastructure — the "building blocks" of an organized society — must be monitored and considered.
For example, a sewer system must be built in such a way it doesn't compromise the groundwater drinking supply or a nearby waterway, such as a river. For a tunnel or interstate highway to be built, the soil may need to be stabilized in some areas. This is because the ground is constantly shifting.
Why Does Soil Become Unstable?
The soil relies heavily on ground cover such as grass and trees to keep it in place. The roots of the vegetation keep it anchored and prevents soil erosion. When large areas are logged or are burned from forest fires, the soil becomes unstable.
In areas located around known faults, such as California, the earth moving sometimes results in earthquakes, but even in areas not known to have massive faults, massive rocks, and slabs of earth are still shifting deep within the earth's crust. Tunneling into the earth can exacerbate this. Before new infrastructure can be built, the engineers decide if the soil must be stabilized.
How Is Soil Stabilization Done?
A civil engineer who specializes in soils does an evaluation of the type of soil and its characteristics in the building area. Some soils are more compact, have drainage issues, or have more pore space, which can affect its ability to bear the weight of the project or cause it to settle, thus, the soil may need to be shored up.
To stabilize soil, grout is injected into the air pockets or other voids in soil. This was traditionally done with Portland cement, but other substances that are considered more environmentally-friendly are being increasingly used. When the cement, clay, or other chemical polymers are used, the soil becomes a solid mass. While this project is frequently done prior to a construction project, it may also be done after if structures are show signs of shifting and sinking.
For more information, contact a company like T. Luckey Sons, Inc.