accumulate vs bank up

accumulate

verb
  • To heap up in a mass; to pile up; to collect or bring together (either literally or figuratively) 

  • To gradually grow or increase in quantity or number. 

adj
  • Collected; accumulated. 

bank up

verb
  • To press a mound of something against something else. 

  • To make a mound to guard against something. 

How often have the words accumulate and bank up occurred in a corpus of books? (source: Google Ngram Viewer )