The Gravity of Cave Ins

How many pushups can you do?

When discussing why soils cave in during the introduction period of an excavation safety class, it’s interesting to see the response when I ask “how many pushups can you do?”.

The answers always vary, but the follow up question gets us to the point. “Why can’t you do a million pushups?”

The answer of course is gravity.

Because of gravity there is a limit to the number of pushups someone can do.

Because of gravity soils will cave in.

Because of gravity we need to have a protective system when the excavation is five feet or deeper.

Because of gravity we need to have a protective system when its less than five feet deep and the soil that caves in can hit someone.

In an ideal universe, the soil walls would stay vertical as long as we would wish. However, due to gravitational forces in this universe, all soil walls will collapse. Therefore, any vertical excavation sides must be dealt with to keep the soil from hitting someone.

We can slope the sides to prevent a cave-in.

We can shore the sides to prevent a cave-in.

We can use a shield system to protect from cave-ins.

But we need to do something because soil that caves in causes serious injuries and even death. That is the gravity of the situation.

It’s just that simple.?