I know someone that excavated cave floors in just this manner. He found some quite interesting fossil bones.
Pretty neat.
Marble (Marvel) cave in Silver Dollar City Mo is built kind of like it. An opening at the top and it widens out to a large room that was once filled with guano (bat poo).
To save on rope one man were executed by throwing him into the cavern.
Done been cleaned out and is open to the paying public.