What Causes Sink Holes to Form
Typical Concrete Driveways are 3-1/2 inch with wire mesh just because 2x4 forms are used....but most go for 4 inch and I go for 5 inch thick concrete. If heavy truck traffic or tractors..then even thicker.
Looks like concrete layed on plastic with no wire mesh and maybe some conduits under the concrete for electrical or something. And....some other access corridors under the concrete. Definitely would not expect heavy traffic on this floor and the tile would cover ALL pending cracks from concrete shrinkage with the plastic keeping moisture from reaching the tile above.
What a disaster
and could have happened outside as well as under some nice corvettes. But maybe some of those conduits you see are water lines that begin leaking over a long period of time. Which would be the reason why the sink hole happened where it did. A reason I do not like water lines under concrete...always go around any concrete flooring with water lines if possible for the simple reason it is easy to find and repair water leaks.