Trench Boxes are shoring devices used in trenches allowing workers to complete their work safely and are typically made of aluminum or steel. Trench Boxes are made of 2 plates which will line the trench walls during construction and are held in place by ‘spreaders’ in between them.
When installing pipe in a trench with trench box shoring, a common rule of thumb for amount of space needed from the edge of the trench box to the edge of the pipe bell is 8-12″ minimum. Trench boxes are engineered to be able to withstand a significant amount of pressure. As work in one area of a trench is completed, the trench box can be pulled into the new position by way of chains, cables, and hooks with the previously shored location being backfilled quickly.
Trench boxes can vary from small to extremely large and heavy. Some larger trench boxes can only be moved with large excavators. When used in deep, wet, and unstable soil trenches, trench boxes may become stuck and nearly impossible to remove with standard excavators. It is not unheard of for a trench box to be essentially lost underground when it has sunk in wet soils and cannot be pulled out. In these cases it may simply need to be left in place and backfilled. Transportation for large trench boxes is typically done on a flatbed semi trailer due to their size and weight.