dynamic terrain

I have a question for my new project. I would like to create a mining game where i can mine everything from the world and dump it back into the world. i looked already in the voxel plugin but i cant see something what i want to make.

I want to have a map with different materials and if i dig something away i dont want a tunnel or mineshaft. The material from the top should move down.

Is there some plugin to make this happens? i dont know if my explanation was very good so i put a link from captain of industries in to check what i mean. Captain of Industry Mining and Dumping #5 - YouTube

Would be nice if anyone can give me a tip where to find some informations