Trenches are one of the most common types of excavation found on a construction site, can be of varying sizes and depths, and are designed to accommodate varying installations. As with all construction processes, the safety of those working on the site, and those operating inside a trench, is paramount. In order to combat the inherent risks of working in and around trench, and allow works to continue unimpeded, most contractors will choose to use trench boxes. In this article, we’re going to look at what these are, and why construction operatives may choose to use a mini box.
What Processes Require a Trench Box?
Modern construction necessitates numerous underground utilities and laid infrastructure. Most buildings are likely to have gas and water lines, power supplies, phone lines, potentially separate fibre broadband lines and more. All of these need to be laid carefully underground, as they could pose a safety or security risk. They’re also likely to be unsightly, and keeping them out of view is often an aesthetic decision as much as it is a necessity.
A trench is therefore the excavation method most sites will use in order to lay this infrastructure. They vary in depths, widths and lengths, but in most instances will require shoring (supporting) so that they can be used effectively and safely.
A straight-walled trench is not the only option open to construction workers who need to lay subterranean infrastructure. They can be excavated with shallow, sloping walls that cannot cave-in, but this naturally requires significant additional space. It is therefore preferable in most cases to excavate a trench and support it with shoring equipment.
What are the Risks?
As trenches are by their very nature temporary excavations, they do not have solid walls that are intended to hold firm of their own accord. This does of course mean that cave-ins and wall collapses are a possibility, and depending on the type of substrate, they could be very likely. In the most serious instances, cave-ins can pose a significant safety risk to site operatives, ranging from minor injuries to entrapment. On the other hand, they can simply be an inconvenience and impediment to works. The other risk of trenches is that they pose a falling hazard - even to those not working in the trench, and in certain cases, even members of the public.
How does a Mini Box Work?
Mini boxes are a straightforward method of shoring trenches. In most cases, they comprise two robust metal panels, with struts spanning between them. The pressure exerted by the struts pushes on the panels in opposing directions, holding the walls of the trench securely. Mini boxes are often used in conjunction with other shoring and excavation safety equipment, such as handrails, ladders and fencing. The boxes themselves ensure the structural integrity of the trench, and attached add-ons such as railings ensure pedestrian safety above.
How Does a Mini Box Differ from a Standard Trench Box?
As their name suggests, mini boxes are smaller versions of a standard-size trench box. They are designed to be used in spaces where the trench isn’t particularly large, and where speed and ease of installation are a priority. Depending on the pressure exerted on the panels, they’re often suitable for trenches up to a depth of approximately 4 metres, and can be used in multiples to cover a larger area. While suitable for a wide range of applications, and useful because of their ease of install, mini boxes are not recommended for heavier waterlogged ground.