pile (something) up
phrasal verb with pile verb uk/paɪl/ us/paɪl/
(FORM A PILE)
成为一堆;把…堆积起来
to form a pile, or to put a lot of things into a pile
(INCREASE)
B2 （使）（不好的事物）增加，（使）累积
(of something bad) to increase
Unpaid bills began to pile up alarmingly. 未支付的账单越积越多，数目惊人。
They piled up such a huge debt that they soon went bankrupt. 他们债台高筑，很快就破产了。