- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 15 Apr 2018
A trench is is an excavation, the length of which greatly exceeds its depth. Shallow trenches are usually considered to be less than 6 m deep and deep trenches greater than 6 m. Trenches are commonly required to allow services, pipelines or foundations to be laid.
Over short periods of time, for relatively shallow depths most soil types will stand almost vertically without difficulty. However, trenches other than those which are relatively shallow may require support.
A trench box is a temporary retaining structure which allows the sides of the trench to be cut vertically or near-vertically. Trench boxes are suitable for low-risk situations in stable, dry ground, often when other solutions, e.g. piling, would be inappropriate.
Trench boxes are typically made from steel or aluminium and are two-sided, supporting both sides of an excavation, separated by spreaders. They require at least two separating struts per panel for stability.
Trench boxes can be placed in pre-excavated trenches or installed using a ‘dig and push’ technique. This involves pushing them into the ground as the excavation proceeds with an excavator removing soil from between the panels, while ensuring that the sides of the trench are supported at all times. The trench width must be sufficient to accommodate what is being laid in the trench, the width of the excavator bucket, and the thickness of the box panels.
 Find out more
 Related articles on Designing Buildings Wiki
Featured articles and news
Dynamo packages data ready for Revit.
How does EVA rate a project's progress?
How can it benefit the built environment?
The benefits of early contractor involvement.
Why it is so important for health and wellbeing.
A highly effective method of managing supply chains.
How it can benefit construction.
Free guide to commissioning for site managers published by NHBC and BSRIA.
Resolving quickly to minimise delay and costs.
Tackling domestic abuse.
Disallowed costs vs. defined costs. Which is which?