Unfortunately, shatter pieces can’t lie in a heap. They can’t be stopped that way.
I can think of one solution:
– the building layer is actually a comp, where the building is at the bottom of the comp.As you shatter the building, the pieces fall out of the comp and disappear.
– something is placed in the beach comp (over the building layer) to obscure the fact that a heap does not appear. Usually a large dust cloud or a sand dune will suffice. Stock footage might be best for the cloud, but you might be able to fake it with Particular.
Normally, this is done with 3D software or miniatures. AE isn’t very good at creating realistic simulations.
Hope that helps,
Steve