pile loop

例句：

1. 1.The pile loops in the center of the room are for displaying books.
   房间中心的堆叠环是用来展示书籍的。
2. 2.The engineer designed a new pile loop to improve the stability of the bridge.
   工程师设计了一个新的堆叠环来提高桥梁的稳定性。
3. 3.The pile loops were used to support the weight of the building.
   堆叠环被用来支撑建筑的重量。