Construction projects involving excavation and trenching are probably the most hazardous workplace activities. An excavation is described as any man-made cut, cavity, trench, or depression that is formed by earth removal. The word “trench” is specific to underground excavations which are deeper than it is wide, being no wider than 15 feet. The fatality rate for all types of excavation job is 112% higher than that of general industry (U.S. Occupational Safety and Health Administration). Given this higher level of danger, it’s critical that safety precautions and controls be utilized constantly and that extreme caution and patience be exercised when doing work in and around pits and excavations.
The 2 basic strategies for protecting workers against cave-ins are sloping and temporary protective structures. Sloping involves cutting back the trench wall at an angle which is inclined from the work area of the excavation. The appropriate angle in the slope depends on the soil conditions at the site of excavation. Temporary protective structures are created to provide protection from cave-ins, collapse, sliding or rolling materials. Examples of temporary protective structures include shoring, trench boxes, pre-fabricated systems, hydraulic systems, and engineering systems.
Shoring is a system that supports the edges or walls and normally requires the use of aluminum, steel, or wood panels which can be backed up by screws or hydraulic jacks. Shoring should be done in conjunction with the growth of the excavation. If you have any delay between digging and shoring, no workers should enter in the unprotected trench. Trench Boxes are often found in open areas which are far from utilities, roadways, and foundations. Trench boxes may be used to protect workers in the event of cave-ins, but they are not a replacement for shoring. In the event the trench or excavation walls are created from rock, rock bolts or wire mesh could be used to offer additional support.
trench jacks are strong steel tubular like instruments that include a 4 part system; A male section, female section, a winding collar and a small stout pin. The Hydraulic Shoring Jacks essentially effort is from the female section accepting the male, allowing the 2 sections to be fully adjustable to some suitable height. The sections have holes in them so that the stout pin could be inserted to ensure they are fixed at the chosen height. The props can then further be adjusted by turning the winding collar.
Each and every end from the female and male sections will be a steel plate which is usually about 150 mm x 150 mm. The plate can there be to help the trench jacks locate a suitable effect on the ground as well as the force to get supported.
There are a number of methods to make use of trench jacks but probably the most common methods are by utilizing them in conjunction with either timber needles or strongboys. Needles in construction are short stout timber beams, as well as an acrow prop could be placed towards each end, where load being supported is in the middle. Strongboys certainly are a more modern method where exvcgw 1 prop is necessary to fix towards the strongboy, which in turn would then be placed in position to support the burden.
If you want to support a wall and you will have chosen to use needles, then the method is usually to knock a couple of bricks from the wall large enough to put the needles through, then at every end an acrow prop could be placed and tightened up to it is tight between the brick and ground level. It is a two man job and can be very trick to have the needles to balance whist setting them correctly in place.
Using strongboys is actually a far simpler method since it is usually only a case of hacking out a mortar joint in which the load is going to be supported, then inserting the long, thin arm in the strongboy in. Similar to the needles method, the trench jacks are them tightened up securely. Some great benefits of using strongboys with all the trench jacks however, would be that the load only must be backed up by putting the props at one side from the wall.
It’s important to understand that collapses can occur out of nowhere, whatever the depth. Actually, the vast majority of fatalities occurs at minimal depths when workers fail to appreciate the risks involved. All excavation projects present serious safety risks, but injuries and fatalities caused by collapses are preventable with proper planning and safety precautions.