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Foundation Digging

Foundation Digging

Digging foundations is one of the oldest types of work with both construction and excavating. Prior to World War 2, foundations were dug by hand. As workers dug the foundations deeper, the sides needed to be shored or supported, to keep the walls of the foundation from caving in.

Following the World War, several innovations were made in backhoes, and foundation hand digging seemed to gradually fade away as hydraulically actuated backhoes were developed, which make it possible to rapidly dig very deep foundations. Resulting from the innovations with backhoes, and because there were no workers inside digging the foundations, the walls no longer needed to be shored.

All types of foundations have what’s known as a stand up time. This time is the amount of time that elapses from the time the ditch is dug until the time the foundation walls start to collapse. The stand up time is dependant on many factors, which include the type of soil, water content, foundation depth, weather conditions, and whether or not the soil has been disturbed .

The stand up time can be as short as zero seconds or as long as several months, as they are very
difficult to predict. Before the foundation can be dug,someone must take soil samples as way of estimating the stand up time. Keep in mind that the soil conditions can be dramatically different only a few feet from where the sample of the soil was taken.

After the foundation digging or the trech has been dug, workers will go down into the foundation, and perform whatever work is needed, such as raising the foundation wall, laying pipe or installing telephone lines, welding pipe, or installing valves. If the foundation walls aren’t supported, there is the possibility of the walls collapsing and trapping the workers in
the foundation. Throughout history, there have been 100 – 300 people killed in the U.S. each year due to foundations collapsing

The public has become very aware that industrial progress will often have negative side effects as
well. The place of engineers protecting the public from these types of side effects is a very controversial issue. The use of trench / foundation boxes on the site, will help to ease this debate.

The trench box, also called a foundation shield, may be placed in the foundation to prevent failures from Injuring workers. The box consists of two large plates, normally made from steel, which are parallel to the walls of the foundation, and horizontal cross members which will hold the two plates apart.

The lower edge of the trench box rests at the bottom of the trench, with the top edge of the box extending above the top of the foundation. The workers will stay between the plates of the box, so that if the foundation does collapse, the dirt will be stopped by the outside of the box.
As the work progresses, the foundation box is pulled along in the foundation with a backhoe or other machine.

When a project calls for a large excavation such as  foundation  digging for a tall building, the
Supporting structure for the excavated walls will be specified in the plans. The big problem with not using trench or foundation boxes occurs in cities, when water or sewer lines are being installed or repaired. The engineer doesn’t specify for the trench box in the plans, but instead leaves it up to the contractor.

Anytime you are going to have  foundation digging or working in trenches, you should always use common sense and take your time. Trenches can be very deadly, especially if trench boxes aren’t used. To be on the safe side, you should always use a trench box if you need to be in the foundation. If you don’t need to be in the foundation – do the smart thing and let the machines do all of the work.

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