An unsupported excavation can create an unbalanced stress in the soil, which, in turn, causes subsidence at the surface and bulging of the vertical face of the trench. If uncorrected, this condition can cause face failure and entrapment of workers in the trench.
What are the hazards of excavation?
Types of Excavation Hazards
- Asphyxiation due to lack of oxygen.
- Inhalation of toxic materials.
- Excavated Soil or Equipment falling on workers.
- Moving machinery near the edge of the excavation can cause a collapse.
- Falling, Slips, Trips.
- The accidental severing of underground utility lines/power lines.
Which of the following are common hazards at excavation sites?
Top 5 excavation safety hazards
- Cave-ins. Trench collapses kill an average of two workers every month, making this a serious threat to worker safety. …
- Falls and falling loads. Workers and work equipment can fall into an excavated area. …
- Hazardous atmospheres. …
- Mobile equipment. …
- Hitting utility lines.
How far should spoil piles and tools be kept from the edge of an excavation?
Keep excavated soil (spoils) and other materials at least 2 feet (0.6 meters) from trench edges. Know where underground utilities are located before digging. Test for atmospheric hazards such as low oxygen, hazardous fumes and toxic gases when > 4 feet deep.
What is the typical point of failure in an excavation?
Soil failure is defined as the collapse of part or all of an excavation wall. The most common soil failure is typically described as an unexpected settlement, or cave-in, of an excavation. Soil sliding is the most common factor leading to soil failure.
What are the safety precautions for excavation?
Avoid underground services and make sure not to undermine nearby structures – use safe digging practice and dig away from them. Check the excavation each day before starting work and after any event that may affect its stability. Provide safe access to get in and out. Prevent collapse – shore, bench, or batter back.
What is the primary concern for excavation?
The main hazards associated with excavation work include: Surface encumbrances. Excavation collapse. Loose rock or soil.
What are the major types of caught in and caught between hazards?
Types of Caught-in or -between Hazards
unprotected excavations and trenches; heavy equipment that tips over, collapsing walls during demolition; and. working between moving materials and immovable structures, vehicles, or equipment.
How are excavations prepared?
Make sure the equipment and precautions needed (trench sheets, props, baulks etc) are available on site before work starts. Battering the excavation sides – Battering the excavation sides to a safe angle of repose may also make the excavation safer.
What are 3 main protection methods against cave-ins?
To prevent cave-ins: SLOPE or bench trench walls. SHORE trench walls with supports, or. SHIELD trench walls with trench boxes.
How far back shall spoils be place from the edge of an excavation?
Set spoils and equipment at least 2 feet back from the excavation. the trench to prevent equipment and spoils from falling back into the excavation.
What type of soil Cannot be benched?
Type C soil cannot be benched.
What are the three methods of excavation?
Types of excavation
- 3.1 Cut and fill excavation.
- 3.2 Trench excavation.
- 3.3 Basement excavation.
- 3.4 Road excavation.
- 3.5 Bridge excavation.
- 3.6 Dredging.
- 3.7 Over excavation.
What is the difference between excavation and trenching?
OSHA defines an excavation as any man-made cut, cavity, trench, or depression in the Earth’s surface formed by earth removal. A trench is defined as a narrow excavation (in relation to its length) made below the surface of the ground.
What is benching in excavation?
Benching means a method of protecting workers from cave-ins by excavating the sides of an excavation to form one or a series of horizontal levels or steps, usually with vertical or near vertical surfaces between levels.
What is the proper slope for excavation?
B-1.1 Excavations made in Type A soil.
All simple slope excavation 20 feet or less in depth shall have a maximum allowable slope of ¾:1. Exception: Simple slope excavations which are open 24 hours or less (short term) and which are 12 feet or less in depth shall have a maximum allowable slope of ½:1.