Wiktionary
heap up
vb. to increase over a period of time; to accumulate
WordNet
Usage examples of "heap up".
Nevermore would anybody of the Florilegium have to dig and heap up and tamp an earthern curb.
By 1980, the pro tem solution was to heap up the products and burn them: billions of dollars worth, week after week.
You been sprinklin yourself with that perfume I found in a ash heap up on the bluffs?