What is a benched trench?
Injury from cave-in, meaning collapse of a steep wall. Mitigation includes construction of sloped walls ( sloped trench) or stepped walls ( benched trench ). For vertical walls, trench shoring stabilizes the walls, and trench shielding provides a barrier against collapsed material.
What is a trench block?
A trench block was a wood and wire structure that was made to block the trenches and prevent the enemy from advancing through a trench system. The machine gun was the most widely used weapon in world war one.
What are the types of trenches and their uses?
Types and uses. Geology. Some trenches are created as a result of erosion by running water or by glaciers (which may have long since disappeared). Others, such as rift valleys or more commonly oceanic trenches, are created by geological movement of tectonic plates. Some oceanic trenches include the Mariana Trench and the Aleutian Trench.
What is the definition of a trench excavation?
A trench is an excavation in which the depth exceeds (is bigger than) the width. What are the hazards associated with trenching and excavation? Working in trenches and excavations is hazardous to both the workers who work inside them, and to workers on the surface.
What is the name of the water drain at the bottom of a trench?
To prevent the trenches from becoming waterlogged, a narrow drainage channel known as a sump would be built at the bottom of the trench. This would then be covered with wooden trench boards known as duck boards.
How deep were the front line trenches?
The front line trenches were generally about 8 feet deep and between 4 and 6 feet wide. Soldiers would spend around a week in the front line trench then would spend a week in the rear trenches or a rest camp. Life at the front line was not pleasant; soldiers were liable to be hit by enemy fire or sometimes by their own artillery.
Why were trenches not built in straight lines?
This was so that if the enemy managed to get into the front line trench they would not have a straight firing line along the trench. Trenches were therefore built with alternating straight and angled lines. The traverse was the name given to the angled parts of the trench.
Why were sandbags used in the trenches?
Sandbags were used to protect the soldiers from enemy rifle fire. They were, however, less effective in the event of shell fire. Sandbags were also sometimes placed in the bottom of the trench to soak up water.
Why were support trenches important?
The support trenches provided a second line of defense in case the front line trench was taken by the enemy. They also contained first aid stations and kitchens to ensure men in the front line had medical treatment and hot food.
What is the name of the wall farthest away from the enemy?
The parados was the name given to the back wall of the trench – that is, the wall farthest away from the enemy. It would often be strengthened with wood and then covered with sandbags.
What was trench warfare?
Trench warfare characterized much of the fighting during World War One, particularly along the Western Front. Trench systems were complicated with many interlinking lines of trenches.
What is a trench?
A trench can be defined as a temporary excavation in which the length of the floor (bottom) of the trench exceeds the width of the floor, and the depth of the trench is greater than the width of the floor. For ease of nomenclature, many teams identify an excavation as a hole where the floor’s width is much greater than the actual depth of the trench. While there are differences with each, both can be very dangerous situations to deal with.
What are the parts of a trench?
Trenches are made up of five main parts: the lip, or the top two feet of the wall; the belly, or center of the wall; the toe, or bottom two feet of the wall; the wal, which is comprised of the Lip, Belly, and Toe; and the flooor, also known as the base of the trench.
What causes a trench lip to fail?
Lip-in. There are times when the weight of the spoil pile too close to the lip, or heavy machinery operating in the close vicinity of the trench can cause the lip to fail, taking everything on the lip (equipment, personnel, etc.) with it into the trench.
What happens when a trench collapses?
The scene of a trench collapse is a dynamic, high-risk environment that can result in injury and death to workers and rescuers alike. A trench can collapse at any time without any audible or visible warning, especially when there are no protective systems put in place inside the trench. Some victims are would-be rescuers who were unaware of the hazards associated with these incidents; therefore, it is imperative that rescue from these situations should only be attempted by emergency personnel trained in trench rescue. It is imperative that responders who bear this responsibility in their jurisdictions be adequately prepared for these operations.
What is the hot zone in a trench rescue?
The hot zone is the area where the actual trench rescue operations are performed. This area can be up to five times the depth of the trench. Next comes the warm zone , which is the area where the Command Post, Tool Staging, Shoring preparation, and other activities associated with the rescue are taking place. The last area is the cold zone, located around the warm zone, for support operations. This remote area helps to ease load forces on the open trench and is usually at least 20 times the depth of the trench away from the hot zone.
How far below the bottom of a trench can you excavate?
Excavation of a material to a level no greater than two feet below the bottom of the support system will be permitted. Excavated material (also known as the spoil pile) shall not be piled any closer than two feet from the lip of the trench (photo 2).
What is trench excavation?
A trench can be defined as a temporary excavation in which the length of the floor (bottom) of the trench exceeds the width of the floor, and the depth of the trench is greater than the width of the floor.
How to support a trench wall?
Other: In some cases, the trench or excavation walls are made of rock but are not entirely stable. Support the walls by using rock bolts, wire mesh, or a method that provides equivalent support.
What is meant by a trench and an excavation?
A trench is an excavation in which the depth exceeds (is bigger than) the width.
What are the hazards associated with trenching and excavation?
Working in trenches and excavations is hazardous to both the workers who work inside them, and to workers on the surface. The hazards include:
What are cave ins and collapses?
Cave-ins or collapses that can trap workers. Equipment or excavated soil falling on workers (e.g., equipment operated or soil/debris stored too close to the excavation). Falling into the trench or excavation. Flooding or water accumulation. Exposure to a hazardous atmosphere (e.g., gas, vapour, dust, or lack of oxygen).
Why are trench boxes used?
Trench boxes can be used to protect workers in cases of cave-ins, but not to shore up or support trench walls. They can support trench walls if the space between the box and the trench wall is backfilled with soil and compacted properly. Otherwise, a cave-in or collapse may cause the trench box to tilt or turn over. Workers should not be present in the box when it has to be moved.
What is sloping in trenching?
Sloping. Sloping involves cutting back the trench wall at an angle that is inclined away from the work area of the excavation. The angle of slope required depends on the soil conditions. Benching is a similar method to sloping.
What is temporary protective structure?
Saskatchewan Labour defines a temporary protective structure as “a structure or device in an excavation, trench, tunnel or excavated shaft that is designed to provide protection from cave-ins, collapse, sliding or rolling materials, and includes shoring, trench boxes, trench shields and similar structures.”
What is compacting in trenches?
Compacting in Trenches. After soil is backfilled into a trench, the loose material is compacted using some mechanical means, such as a compactor, an excavator, or a "jumping jack"-type compactor .
How is backfill done?
Backfill can also be done using flowable fill, a cementitious material with a low water-cement ratio that is delivered to the job site by a ready-mix truck. Typically, the utility pipe or other equipment in the trench is first covered with an aggregate material, then the flowable fill is placed in the trench directly from the truck, just like regular concrete. The aggregate surrounding the pipe provides for easier access to the pipe for future repairs. One of the challenges when using flowable fill is the liquidity of the fill. Contractors must contain or block the fill to prevent it from flowing into other trench areas.
What is backfilling soil?
Backfilling is the process of putting the soil back into a trench or foundation once excavation, and the related work has been completed. The backfill process requires skills and heavy equipment as well as knowledge of the specifications, contract requirements, and soil conditions.
What is soil lift?
Soil is typically backfilled in layers or lifts. The soil lift will depend upon the nature of the backfill and the compaction equipment that is used. Water may be added during the compaction process, to assist with compaction.
Overview
A trench is a type of excavation or in the ground that is generally deeper than it is wide (as opposed to a wider gully, or ditch), and narrow compared with its length (as opposed to a simple hole or pit).
In geology, trenches result from erosion by rivers or by geological movement of tectonic plates. In civil engineering, trenches are often created to install underg…
Geology
Some trenches are created as a result of erosion by running water or by glaciers (which may have long since disappeared). Others, such as rift valleys or oceanic trenches, are created by geological movement of tectonic plates. Some oceanic trenches include the Mariana Trench and the Aleutian Trench. The former geoform is relatively deep (approximately 10 kilometres (6.2 mi)), linear and n…
Civil engineering
In the civil engineering fields of construction and maintenance of infrastructure, trenches play a major role. They are used for installation of underground infrastructure or utilities (such as gas mains, water mains, communication lines and pipelines) that would be obstructive or easily damaged if placed above ground. Trenches are needed later for access to these installations for service…
Military engineering
Trenches have often been dug for military purposes. In the pre-firearm era, they were mainly a type of hindrance to an attacker of a fortified location, such as the moat around a castle (this is technically called a ditch). An early example of this can be seen in the Battle of the Trench, a religious war, one of the early battles fought by Muhammad.
With the advent of accurate firearms, trenches were used to shelter troops. Trench warfare and t…
Archaeology
Trenches are used for searching and excavating ancient ruins or to dig into strata of sedimented material to get a sideways (layered) view of the deposits – with a hope of being able to place found objects or materials in a chronological order. The advantage of this method is that it destroys only a small part of the site (those areas where the trenches, often arranged in a grid pattern, are located). …
Safety
Trenches that are deeper than about 1.5 m present safety risks arising from their steep walls and confined space. These risks are similar those from pits or any steep-walled excavations. The risks include falling, injury from cave-in (wall collapse), inability to escape the trench, drowning and asphyxiation.
• Falling into the trench. Mitigation methods include barriers such as railings or fencing.
See also
• Abyssal plain
• Cut (earthmoving)
• Cut and fill
• Ditch
• Gully
External links
• Trenching and Excavation (a NIOSH Safety and Health Topic, Centers for Disease Control and Prevention)
• Trench Safety Awareness (a NIOSH Publication, Centers for Disease Control and Prevention)