There are four common types of trench collapse hazards: (1) the spoil pile slide, (2) the shear wall collapse, (3) the belly slough, and (4) the slip slide. Spoil Pile slides (figure 1) are very common and occur when dirt is piled too close to the edge of the trench.
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What is trench Collapse?
A trench collapses when its walls fail to contain the pressure of the tones of soil pressing on it. Even though this can be problematic in any depth, it can accelerate if other materials are piled at the edge.
What is the most common cause of a trench collapse?
Common Causes Of Trench Collapses
Trench collapses and cave-ins can be caused by: Improper sloping: When the trench is not sloped properly, it creates significant risk of increased instability and potential for collapse. Unstable soil: The soil itself is another factor that increases the risk of collapse.
What three 3 methods can be used to support trenches?
Methods of Protection
- Sloping and Benching. This method is considered the safest of the four methods.
- Timber shoring. This method requires installing aluminum hydraulic, pneumatic, other types of supports to shore up the trench face prevent movement of soil.
- Shielding.
- Engineered design.
What are the four trench hazards?
The hazards include:
- Cave-ins or collapses that can trap or crush workers.
- Equipment or excavated soil falling on workers (e.g., equipment is operated or soil and debris is stored too close to the excavation).
- Falling into the trench or excavation.
- Flooding or water accumulation.
What causes excavations to collapse?
Excavations may become unstable or collapse due to: Vibration from vehicles or machinery. Weather conditions and surface water. Severe impact including explosions.
What are the causes of subsoil collapse of trenches?
A trench collapse happens for a number of reasons. Sometimes, the fact that the soil around the trench is dry or is of a material that just does not naturally hold together well can lead to an unexpected collapse. Wet weather and the vibrations from nearby construction equipment can also cause a collapse.
How fast does a trench collapse?
D2000Safety.com explains that when the walls of a trench cave in, the force of the collapse can be just as deadly as the actual weight of the soil. The average cubic yard of dirt weighs roughly 2,500 pounds, and when it falls from a height of six feet, it hits a worker moving at about 14 mph.
What are the OSHA requirements for trenches?
OSHA requires employers to provide ladders, steps, ramps, or other safe means of egress for workers working in trench excavations 4 feet (1.22 meters) or deeper. The means of egress must be located so as not to require workers to travel more than 25 feet (7.62 meters) laterally within the trench.
What are the three methods OSHA recognizes to protect workers from collapsing excavations?
Protective systems include support systems, sloping and benching systems, shield systems, and other systems that provide the necessary protection.
What are 3 types of excavation?
The types of excavations common to these jobs are site cuts, land clearing, cut and fill, site preparation, compacting, and bulk excavations of soil, rock, concrete or other materials.
What are the two methods of trench excavation?
Trench Excavation Methods
- Conventional methods: excavators +/- rock breakers.
- Drill & blast.
- Trenching.
What are the three main types of controls to prevent ground collapse?
There are three primary protection methods that are used in excavation: shielding, sloping and benching.
What are the two key risks that are associated to trenches?
There are known hazards and risks associated with trench construction and excavation. These include trench collapses, cave-ins and side wall deterioration, of these known risks, trench collapse is the most common.
What is the most common hazard during an excavation?
cave-in
Probably the most common hazard at any work site is the threat of cave-in. A cave-in occurs when walls of an excavation collapse. Cave-ins can be deadly. Wall failures often occur suddenly, with little or no time for the worker to react.
What is the greatest hazard while working in a trench?
Trench collapses, or cave-ins, pose the greatest risk to workers’ lives. To prevent cave-ins: SLOPE or bench trench walls.
What are the different types of excavation?
10 Types of Excavation
- Bridge Excavation. Whether you’re building arch, beam or suspension bridges, you need a strong foundation to build on.
- Borrow Excavation.
- Channel Excavation.
- Drainage Excavation.
- Dredge Excavation.
- Stripping.
- Earth Excavation.
- Muck Excavation.
How do you prevent excavation from collapse?
The sides of the excavation or trench should be supported by timbering or other suitable means or sloped and battered back to a safe angle of repose to prevent a collapse.
What is risk of collapse in excavations?
Materials Falling into Excavation
Excavated spoil and materials should be placed at a safe distance from the excavations as the extra weight can contribute to a collapse.
What is the 4 soil classifications?
OSHA classifies soils into four categories: Solid Rock, Type A, Type B, and Type C. Solid Rock is the most stable, and Type C soil is the least stable. Soils are typed not only by how cohesive they are, but also by the conditions in which they are found.
What prevents trench walls from collapsing?
Both employ aluminum rails and hydraulic cylinders that apply pressure to the walls of a trench, creating an “arching” effect in the adjacent soil that prevents the walls from collapsing. Trench Shields: Trench shields are aluminum or steel structures designed to protect workers by withstanding the forces of a cave-in.