There are a variety of different components that make up a retaining wall. These components include a base slab footing, a construction joint, a stem, and a shear key. It is important to be aware of the various types of retaining wall blocks adelaide that can be used for your building project, and the best way to choose the right one for your needs.
Base slab footing
The retaining wall base slab footing plays an important role. It provides support and prevents overturning of the base.
A retaining wall can be an effective tool for optimizing land use. These walls are usually freestanding, but they can be tied into the foundation. They separate grade differences and are often used for landscaping. Retaining walls are made of concrete, masonry or geosynthetics.
A typical basement retaining wall is composed of a stem and toe slab. The stem supports the top wall, and provides lateral resistance to it. In addition, it acts as a cantilever beam. Toe slabs are subject to a vertical load on the back side of the wall.
Toe slabs are often reinforced with a steel plate on their back. This plate is secured with a steel rebar. The slab will not bear on permanent frozen soil if it is built on a shallow foundation.
For buildings that are susceptible to earthquake forces, reinforcement is especially important. The slab is usually made from a well-compressed granular fill. Sands, stiff clays and marl are good bearing characteristics.
The footing’s total pressure can be as high as one-third of the depth at the lowest point. This pressure is dependent on the angle of internal friction. It can be optimized if the rebars have been cut alternately.
Footings must be sufficient in thickness and width. Their edge thickness should be no less than 8 inches. The edge thickness for Group R-3 occupations may be less than 6 inches
Foundations must be cast at least 1’6″ to 2’0″ deep. The footings should be stepped if necessary during construction.
Shear key
A Shear Key is a structural element which is used in many kinds of structures. Shear keys are required for structures such as basements, bridges, culverts, and retaining walls. It can be either constructed from concrete or steel.
The shear key is placed at the base of the retaining wall. This component adds additional resistance to lateral loads to the structure. Hence, the overall stability of the wall increases as the depth of the shear key increases.
The depth of the shear key should be 0.508 m and its width should be 0.381 m. These values are calculated according to the construction standard ACI 318-17.
The thickness of the shear keys should be twice as deep as the shear keys. The width should be at least twice as wide as the depth.
The shear key’s main purpose is to transfer the shear force between the retaining wall and the key. Nevertheless, it cannot transfer the bending moment.
The friction between the soil and footing resists the lateral load on the wall. Passive pressure on the shear keys also helps to resist it. Moreover, the passive soil pressure will bend the shear key away from the sliding direction.
The main factor determining the strength of the retaining wall is its ability to resist lateral and gravity loads. These forces are usually considered during the landscape design adelaide process. However, special design is necessary for the critical loads.
The active and passive forces on the retaining wall are evaluated using Rankine theory. The passive lateral soil resistance was calculated at 150 psf/ft.
Stem
A stem of retaining walls is a structural device that supports a house. It can be made of concrete or masonry. The construction of the stem is a multi-part process.
A stem wall is usually required in earthquake-prone areas. It supports the structure and prevents it from falling in the case of a natural catastrophe. This is because it provides a solid foundation and distributes load over a larger area.
The exact size of the foundation depends on the bearing capacity of the structure. In single story buildings, the bottom footing pad is 12 inches. The pad for two-story structures is 15 inches.
Sometimes, structural engineers are called upon to evaluate earth retaining walls that have failed. It will settle if the foundation is weak enough. To prevent the wall from slipping off, vertical bars should also be installed into the base during construction.
Stems are typically constructed from concrete or masonry. The main reinforcing steel should be placed on the backfill side.
As the height of the structure increases, the lateral load on the stem will increase. The additional load is called the surcharge load. The horizontal loads and the lever arm are taken into account when calculating the load.
The stem of most retaining walls is designed to resist shear forces. However, lateral pressures can cause the wall to rotate about its toe.
Monolithic slabs can be an affordable alternative to stem walls. They are also easier to construct.
Unlike stem walls, monolithic slabs do not require a crawl space. However, it may require compacting the dirt.
It may be necessary to purchase additional equipment depending on the project’s size. For larger projects, rollers are required.
Construction joint
A retaining wall is complete with construction joints. They are located at the footing and wall joints, as well at the base of the wall. These are designed to enhance the strength and constructability of the wall.
The horizontal joint between the footing of a wall and the wall is the main construction joint. This joint should not be the only one. There are also vertical joints and expansion joints. Typically, these are used in larger civil engineering structures.
A control joint is an in-concrete device that aids in the transfer of shear or axial loads. It is usually a grouted key. This increases the wall’s slip resistance.
Sliding joints can be used in both precast concrete and water structures. They are also used in wall floor junctions.
Movement joints are built into walls for a variety of reasons. Some are quick, while others are gradual. Some of these movements can be reversed depending on the span.
Contraction joints are vertical joints that are placed at regular intervals. They are used to limit wall movement caused by temperature changes.
These are usually small, about one-fourth of an inch wide. These are useful in dealing early-age thermal movements. Also, they allow the concrete to shrink.
The ASTM C90 specification provides the minimum area of reinforcement required for each unit. It is recommended that the reinforcement area be at least twelve inches by two inches.
There are also special units shapes that provide fire-rated and out-of-plane load transfers. Check with local concrete masonry manufacturers to determine the appropriate shape and spacing.
Geotechnical and structural design requirements
Retaining walls are a structural and geotechnical requirement that support the stability of a project. These structures can be used to support marine structures, building foundations, and underground structures. Depending on the purpose of the structure, the engineer designing it may select the parameters for the wall based on research into the soil type and engineering properties.
The engineer will also consider factors that can contribute to a failure of a retaining wall. Some examples of such factors are failing joints such as shear keys, dowels, and connections between framing elements. In addition, water is the most common cause of retaining wall collapse.
There are many types of retaining walls. They can be gravity walls, braced walls, or temporary or permanent sheet pile walls. These are the most popular, but there are many other options for a retaining walls. It may also need additional protection against flooding or surface runoff.
A retaining wall can be designed based on geotechnical research, and the results of a Geotechnical Report. This will require a qualified expert. Retaining walls over four feet in height are subject to a building permit requirement by most governments. Using a registered professional can reduce the chances of any problems occurring.
Eurocode 7 is a European standard that addresses all aspects of geotechnical and structural design. The document includes many new normative standards. Eurocode 7 uses a limit state design method that includes partial factors, which is different from previous British Standards.
For the geotechnical investigation, the registered design professional will determine the scope of the geotechnical investigation, the number of borings, and in-situ testing equipment. The registered design professional will also determine the laboratory testing schedule.
