Sinkholes in Florida
Sinkholes are perhaps some of the strangest occurrences on the planet, and they happen worldwide. They can either be natural or man-made, but the end result is the same: a gaping hole in the ground that causes damage to the land and surrounding structures. In southern states of the U.S, sinkholes are relatively common occurrences because the type of topsoil and underlying limestone formation are generally weaker than in other parts of the country. Particularly in Florida, sinkholes are a natural and common geological hazard across the state.
How Do Sinkholes Happen?
Both man-made and naturally occurring sinkholes happen because underground water erodes the structure of the land. The ground beneath our roadways and landscapes is comprised of soil, tiny rocks, and large bedrock deposits. In some areas of the world, this underlying limestone is already somewhat weak because it is not tightly packed together. Water can seep in to the ground and eat away at the underlying bedrock, causing cracks to open. As these cracks widen, the soil and rocks above begin to fall in and further exacerbate the problem. If the topsoil is not compacted well, it falls in to the cracks at an alarming pace. As this happens, the underlying structural integrity of the bedrock is significantly weakened and eventually gives way, causing a collapse and the opening of a sinkhole.
Why Are Sinkholes Common in Florida?
Sinkholes are more common in Florida than in any other state in the country. Why is this? It is because of the natural rock that is Florida’s underlying limestone. In northern states, bedrock is mostly made of hard granite, which is why sinkholes are less common. Florida’s bedrock is mostly limestone, which is porous type of rock that readily absorbs water. Pair this porous stone with loose sandy or clay-like topsoil and you have the formula for a sinkhole problem. The loose topsoil does nothing to protect the underlying limestone, which then drinks up all water that comes into contact with it. The water becomes acidic on contact and washes away large portions of the rock. Any cracks and fissures this creates allow topsoil to sink in, making depressions in the land above.
How Are Sinkholes and Repaired?
Sinkhole repair requires a lot of work and demands accurate assessments and repair plans immediately following the event. The clean up is a collaborative process that requires a team of experienced structural engineers, planners, construction workers, disaster workers, and many others. Some surrounding structures may need to be demolished if they’re irreparable. Underground sewer and drainage lines need to be cut, capped, and secured.
Once the area is safe, repairs can begin. Foundation-damaging occurrences like sinkholes almost always require compaction grouting and possibly underpinning. These methods require an experienced design team of geotechnical engineers along with structural engineers to get the job done.