pile up, cram in

(つむ) To pile up things (luggage, cargo, crap) or, to accumulate. Almost always used like this:積み上げる.
げる(つみあげる) Pile up.
ねる(かさねる) To overlap (usually said of flat things). Also, mostly it is used in the figurative sense:problems or responsibilities are growing out of control, you can’t do it all at once!
める(つめる) To pack in, stuff in, cram.