Trench support
Contents |
[edit] Introduction
A trench is defined as an excavation when its length greatly exceeds its depth. Shallow trenches are usually considered to be less than 6 m deep and deep trenches greater than 6 m. Depending on the dimensions of a trench, excavation can either be carried out by hand or using a mechanical digger. Trenches are commonly required to allow services, pipelines or foundations to be laid.
Water ingress into the trench is often a major issue and ground water table locations and soil strata should be investigated before any extensive excavation takes place.
Over short periods of time for relatively shallow depths most soil types will stand almost vertically without any problems. However, trenches other than those which are relatively shallow may require a trench support scheme.
[edit] Timber supports
Historically, trenching involved using timber to support horizontal and vertical soil loads and this technique is still used today. Timber trenching is generally used for low risk, narrow trenches, shafts or headings. The timber solutions require good workmanship and are reasonably labour-intensive, however they are versatile and the equipment required is easy to handle and transport.
[edit] Trench boxes
Trench boxes are suitable for low-risk situations in stable, dry ground and can be placed in pre-excavated trenches or installed using the ‘dig and push’ technique. The system requires at least two struts at each panel for stability which must be considered when access is required for construction work or piping.
For more information, see Trench box.
[edit] Trench sheets
Trench sheets are the most adaptable of the systems available, and are most commonly used to retain poorer soil. They can support deeper trenches with larger surcharges and provide a continuous support. They require multiple levels of strut support and the slenderness of the sheets can often limit the depth of the trench as they are installed by light machinery and could buckle under large vertical loads.
[edit] Related articles on Designing Buildings
- Backfilling.
- CDM.
- Crane supports.
- Demolition.
- Excavation.
- Facade retention.
- Falsework.
- Formwork.
- Health and Safety.
- Scaffolding.
- Shoring.
- Strut.
- Temporary works.
- Trench box.
- Trenching equipment.
- Tunnelling.
[edit] External references
- BS5975:2008 + A1: 2001 Code of Practice for Temporary Works Procedures and the Permissible Stress Design of Falsework (BSI 2011).
Featured articles and news
C20 Society; Buildings at Risk List 2025
10 more buildings published with updates on the past decade of buildings featured.
Boiler Upgrade Scheme and certifications consultation
Summary of government consultation, closing 11 June 2025.
Deputy editor of AT, Tim Fraser, discusses the newly formed society with its current chair, Chris Halligan MCIAT.
Barratt Lo-E passivhaus standard homes planned enmasse
With an initial 728 Lo-E homes across two sites and many more planned for the future.
Government urged to uphold Warm Homes commitment
ECA and industry bodies write to Government concerning its 13.2 billion Warm Homes manifesto commitment.
From project managers to rising stars, sustainability pioneers and more.
Places of Worship in Britain and Ireland, 1929-1990. Book review.
The emancipation of women in art.
Call for independent National Grenfell oversight mechanism
MHCLG share findings of Building Safety Inquiry in letter to Secretary of State and Minister for Building Safety.
The Architectural Technology Awards
AT Awards now open for this the sixth decade of CIAT.
50th Golden anniversary ECA Edmundson awards
Deadline for submissions Friday 30 May 2025.
The benefits of precast, off-site foundation systems
Top ten benefits of this notable innovation.
Encouraging individuals to take action saving water at home, work, and in their communities.
Takes a community to support mental health and wellbeing
The why of becoming a Mental Health Instructor explained.
Mental health awareness week 13-18 May
The theme is communities, they can provide a sense of belonging, safety, support in hard times, and a sense purpose.
Mental health support on the rise but workers still struggling
CIOB Understanding Mental Health in the Built Environment 2025 shows.
Design and construction material libraries
Material, sample, product or detail libraries a key component of any architectural design practice.