Many types of excavation work are suited to specific construction projects. Here are the main ones:
Level Ground Excavation helps create foundations for buildings below ground level.
The processes involved in building roads, railways, and canals include adding or removing large masses of dirt and stone. These additions and removals are commonly referred to as cut and fill excavation. These processes are usually carried out using heavy machinery such as excavators and bulldozers. The type of mass being added or removed depends on the construction project.
For example, earth excavation is typically used when building a foundation, as it strips the layer of soil underneath the topsoil for construction purposes. Another common excavation type is rock, used to clear rocky surfaces that hinder the building process. Rock excavation is challenging, requiring special equipment, such as drilling or blasting.
One of the main considerations in cut-and-fill excavation is calculating how much material will need to be moved between different sections. This is determined by measuring the existing topography of a plot of land and determining how much space is required for construction. The remaining area is then split into cut and fill sections, with the former section having a lower elevation than the latter. Calculating how much material will need to be removed from a site before construction begins is important, as this helps minimize the amount of hauling required for the job.
This type of excavation also considers the field shrink and swell factor for the material being transferred between the cut and fill sections. The amount of material that shrinks or swells as it is relocated will impact the time it takes to build the project and ultimately influence the cost.
The cut-and-fill process needs to conserve as much mass as possible. Having more cut than fill will result in project managers needing to find somewhere to dispose of the excess dirt. Having more fill than cut means that additional mass will be brought in from elsewhere on the site, increasing labor and equipment costs. For this reason, cut-and-fill excavations are designed to keep the cut-and-fill mass relatively equal.
Trench excavation involves digging a narrow cut, cavity, or depression in the earth’s surface that is deeper than it is wide. It can be found on construction sites and is the most common form of excavation. According to OSHA, trenching is the leading cause of workplace fatalities and requires high worker safety training and protective systems.
This type of excavation focuses on removing material, usually dirt and rock, to clear surfaces like rocky areas that impede building structures. It may also be used to dig drainage ditches that funnel water away from habitation, infrastructure, and agriculture or to remove sediment deposits in waterways to make them passable.
A trench can be any length and depth, although deep trenches typically have a length that greatly exceeds their width. This type of excavation is commonly used to lay foundations for buildings or bury services such as pipes, and it often requires specialty equipment and procedures.
Identifying the soil types related to a specific trench or excavation is important before beginning work. This information helps determine the proper excavation, support, and backfilling methods. Additionally, it is helpful to identify if the trench will have underground utilities or other hazards that must be avoided.
The type of soil, its consistency, ease or difficulty in excavating, appearance, and water seepage are some of the characteristics that influence the best methods. Sometimes, a single trench can contain soil types that vary widely from one end to the other.
A competent person must review the site before starting work, identifying and marking all buried services appropriately. It is also important to know the location of nearby vehicles, equipment, and structures that could put pressure on or undermine the trench walls. Finally, the competent person should check the area for signs of hazardous gas, vapors, or dust and ensure all equipment is de-energized before entering the trench. Remember to complete and share a job hazard analysis, update your written accident prevention program, and conduct routine equipment inspections.
Once a site is identified, the archaeological team must decide which excavation method to use. The choice is usually based on the natural geography of the site, the strata, and cultural layers, and how much time the archaeologists have to complete the excavation.
Shovel test surveys, shovel test pits, probes, and trenches are all common excavation types. Each type allows the archaeologists to explore different areas of a single layer while enabling them to record their findings.
Once the archaeologists have selected their excavation method, they must map the site. This includes establishing a grid system, or datum, to make all future measurements. The datum can be a specific location or feature on the site, such as a boulder, building, or fence post. Alternatively, it can be a point in space, such as a GPS coordinate.
The next step is to establish the phasing of the site, which helps determine the chronology of the layers of the site and provides the context for the interpretation of artifacts and features. Phases are usually arranged chronologically and can be grouped into domestic, commercial, or industrial categories.
When the phasing is completed, the archaeologists can begin excavation. This often involves digging in the order that the phases were deposited, which ensures that the artifacts are removed from the soil in an order consistent with the sequence of human activity at the site.
Rebar is vital in construction projects such as skyscrapers, highways, and bridges. It adds great strength to concrete and helps prevent cracking that might destroy a project. Rebar is almost always made of steel, which provides excellent tensile strength. It is sometimes coated with zinc or another metal to help prevent rusting. Alternatives to steel rebar include glass fiber-reinforced polymer (GFRP) and carbon fiber.
Footing excavation is digging and removing dirt, rocks, or other materials that make up the foundation of a building or different structure. This type of excavation is often done to prepare for construction, install utilities, or create basements. It can also be used to create slopes or level uneven terrain. It is usually performed with heavy machinery like excavators and backhoes and power tools such as jackhammers and concrete cutters.
Stripping is a type of excavation that is focused more on clearing a large area than digging a pit or trench. This excavation method removes wide swaths of topsoil, gravel, or other materials to prepare the site for construction or engineering projects. It can also be used to clear out contaminated or otherwise undesirable areas.
This type of excavation is generally related to the construction of a bridge. It involves removing any materials that might interfere with the construction of the foundations, substructures, and so on needed to support a bridge. This is a complex operation that requires different types of equipment than other forms of excavation.
During tunnel excavation, workers dig and remove soil, rock, or other material to create a passage through the ground. This is often done for infrastructure, including roadways, subways, canals, or sewage systems. This type of excavation is typically done under the direction and approval of a professional engineer.
In addition to being used in constructing skyscrapers, bridges, and other structures, rebar is also widely used for more esoteric purposes, such as minimalist art and coffee tables. Rebar is most commonly made from steel, which has excellent tensile strength and doesn’t easily bend. Alternatives to steel rebar include GFRP, which offers good tensile strength but isn’t as strong as steel.