There's a lot of work piled up on my desk.

瞧我桌上堆了一堆的事。

pile up，就相当于accumulate，即，堆积。
例句：
The clouds are piling up. 云愈积愈密。
One car made a sudden stop and the car behind it piled up.
一辆汽车突然刹车, 与后面跟着的那辆汽车相撞。