堆积 (duī jī): to pile up; to heap; accumulation

Many old books and magazines have piled up in the corner of the study; I plan to sort them out this weekend.

Because of working overtime continuously, the documents on his desk have piled up like a mountain, almost blocking even the computer screen.

Autumn has arrived, and thick fallen leaves have piled up in the yard; the children love jumping up and down on them.

If garbage keeps piling up in the hallway and is not cleared away, it will not only give off a bad smell but may also attract rats and cockroaches.

At the end of the year, work piled up more and more, and he had to work overtime until late every day to finish his tasks.