Retaining Wall Anchoring Definitions & Importance | Advantages of Anchored Retaining Walls

Retaining Wall Anchoring Definitions & Importance | Advantages of Anchored Retaining Walls

What is Retaining Wall Anchoring? | Retaining Wall Deadman Anchors| Types of Retaining Wall Anchoring | Advantages of Anchored Retaining Walls

What is Retaining Wall Anchoring?

Anchored retaining walls are fastened at the top and bottom with cables or other supports anchored in the rock or soil behind them.

Anchors are pushed into the material and then enlarged at the cable’s end, either mechanically or by pumping pressure concrete into the hole.

Anchoring devices ensure that the panels on the retaining wall have proper support and won’t be susceptible to the forces of gravity or be pulled away by high winds.

A retaining wall is a structure that holds back, or prevents erosion by acting as a barrier against natural forces such as water or soil. In this post we will discuss how to anchor the retaining wall to the ground.

In other words, it is a concrete or masonry wall that uses its weight and gravity to resist forces of natural movement and erosion in order to prevent items behind the wall from being carried away due to those forces.

Retaining walls come in various forms such as a long retaining wall, or a short retaining wall. A short retaining wall is usually used to hold back an area of material, whereas a long retaining wall is usually used to hold back an entire slope.

Retaining Wall Deadman Anchors

Anchored retaining walls are fastened at the top and bottom with cables or other supports anchored in the rock or soil behind them.

Anchors are pushed into the material and then enlarged at the cable’s end, either mechanically or by pumping pressure concrete into the hole. After that, the pressured concrete expands to form a bulb in the earth.

This retaining wall may be sunk at the bottom and linked to a slab at the top, or it could be tied to a “deadman anchor” – a concrete structure that is pushed into the ground or fastened to the soil with enough resistance.

The horizontal cable, rod, or helical anchor, as well as the deadman structure, resist forces that might otherwise cause the wall to collapse.

Although technically complicated, this approach is beneficial when large loads are predicted or where the retaining wall itself must be narrow and would be too weak without anchoring.

Bolts and anchor rods are, in general, the most commonly used devices for anchoring a retaining wall. These are usually built-in into the wall itself.

There are two main types of bolt anchors: flange and pin-up. Flange anchors are used to provide the key connection point inside the wall and pin-ups provide a more secure anchoring point outside of the wall for adding strength to it.

Below you will find various methods on how to anchor the retaining wall:

1. Anchoring retaining walls with gravity

The most common way to anchor a retaining wall is through gravity. In other words that you will use the force of gravity in order to create a level and straight wall.

This method is usually used when the height of the wall or slope is greater than 2 meters, otherwise if you have a slope which has an inclination less than 2 meters then you might want to use another method.

2. Anchoring retaining walls with fasteners

Anchoring retaining walls with fasteners is a very common way to anchor retaining walls. There are many types of fasteners which can be used for this purpose.

They are usually made up of steel, metal or concrete materials and are intended to be used in order to create a strong bond between the wall and the ground.

3. Anchoring retaining walls with adhesives

Another popular way to anchor retaining walls is by using adhesives. Adhesive is sometimes also called “retaining wall points”. In other words, they are meant to be used in order to attach any type of material to the ground.

4. Anchoring retaining walls with bolts and brackets

Bolts and brackets are the most useful and efficient anchors for retaining wall anchoring. They are normally used in order to create bends or changes of direction on a wall. They are very easy to install, and have high capacities.

5. Anchoring retaining walls with wedges and jacks

Wedges and jack are two types of fasteners which can be used in order to create a change of direction or bend on a retaining wall.

While wedge is meant to be used in order to create a smaller bend on the retaining wall, jack is often used when the slope angle is greater than 15 degrees (although this depends on the soil conditions where you will be installing your retaining wall).

6. Anchoring retaining walls with different materials

Anchoring retaining walls with different materials is a good idea when you want to create a different look for your wall.

They are normally used in order to concrete, mortar or stone or in order to polypropylene and adhesives for the purposes of wood-plastic products.

Retaining walls can be anchored in different types of soil such as sand, clay, and others. Depending on the type of soil that you will build your retaining wall then this will also determine how you will anchor your wall to the ground.

7. Anchoring retaining walls with metal brackets and straps

Metal brackets are very useful in order to create a change of direction or bend on a retaining wall. While straps are used to create a straight retaining wall. They are normally made out of steel or aluminum.

Advantages of Anchored Retaining Walls

  1. Anchored walls are structurally reinforced with a variety of methods including pre-cast concrete panels, metal reinforcement, or steel rods.
  2. Anchored walls resist seismic loads better than non-anchored systems.
  3. Excellent foundation conditions can be provided by the use of a sloping wall where the erosion potential is greater in one direction than another, for example, on a drumlin.
  4. The anchor point is adjustable. It can be located such that it will support more weight as the slope increases (elevation).
  5. Anchored walls help to reduce differential settlements and frost heave in some regions of the country by acting as a diaphragm wall.
  6. Anchored walls can be constructed with or without a top cap which allows for the construction of taller walls.
  7. Anchored walls cost less than non-anchored retaining walls since they require fewer materials and less equipment to construct.
  8. For inner-city applications, anchored walls are often more aesthetically pleasing since they can be designed to meet a specific site’s particular need while still allowing for the planting of ground cover on top of them.

Disadvantages of Anchored Retaining Walls

  1. Anchored walls require more time for design and construction than non-anchored systems.
  2. Anchored walls require more specialized equipment and personnel to construct than non-anchored systems.
  3. Anchor tendons are susceptible to damage from subsurface soils, which can create voids in the structure of the wall, resulting in failure.
  4. When anchored walls are designed with a top cap beam, there is a greater probability for tree root intrusion into the wall than with non-anchored walls.

 

Anchored retaining wall FAQs

What is an anchored retaining wall?

A retaining wall system with anchors is a structural feature that is placed through the rock or soil to transmit the tensile pressures produced in the structure to the ground.

Anchored retaining walls are frequently thinner than gravity walls and cantilever retaining walls.

A retaining wall anchoring system consists of two components: the anchors and the anchor plate. The anchors are placed in the ground along a tension cable that runs from the top to the bottom of the wall.

Cable anchors can be buried by an excavating machine into soil, rock or concrete for heavy soils and concrete anchor piles with rebar steel rods running down to floorboards or lighter materials may just be driven into soil directly.

Where are anchored retaining walls used?

Anchored retaining walls are appropriate for loose soil over rocks. This sort of retaining wall construction system can be used to build a substantial retaining wall.

Deep cable rods or wires are pushed deeply sideways into the soil, and the ends are filled with concrete to give anchorage.

How do you secure a failing retaining wall?

The wall can be reinforced by directing part of the shear stress to the base, where it contacts the ground.

This can be accomplished by either extending the foundation’s footing or by adding concrete to thicken the base. Another method for adding strength is to install anchors or tiebacks.

What are anchor bolts?

An anchor bolt is a steel bolt embedded in masonry, concrete or a similar material. The bolt has a point that pierces through to the opposite side which connects it to the wall.

Anchor bolts are used in conjunction with expansion bolts made for use alone or with anchor plates.

What are expansion anchors?

Expansion anchors (also called screw anchors) allow attachment of wood, metal or other materials to concrete walls without causing damage to either surface.

Expansion anchors are used when attaching wood to concrete, metal to concrete, metal to wood and steel or aluminum materials. They are used for attaching signs or other decorative items. The expansion bolt expands as it penetrates the material.

What are hole corrosion problems and how can the expansion anchor solve this problem?

When drilling holes in cement walls for the use of expansion anchors, there is always a chance of developing corrosion.

The hole does not penetrate the entire thickness of the wall but a small portion of it. The corrosion may be either in the form of holes or cracks in the wall.

For this reason, expansion anchors are often used for such applications.

Are expansion anchors better than bolt anchors?

Expansion anchors are always made from stainless steel and come with a corrosion-resistant molybdenum coating. For this reason, they do not corrode as bolts do, and they also last longer without developing holes or cracks over time.

What are the different types of these anchors?

There are expansion anchors designed for use in wood, metal and concrete. Bolt size, length and corrosion-resistant coating determine the type of expansion anchor you should use.

In concrete expansion anchors, the expansion bolt is made from non-corrosive steel material to prevent corrosion in the event that water seeps into the hole.

What are tiebacks for retaining walls?

A tieback is a structural device placed in soil or rock to transmit applied tensile force into the earth. The tieback-deadman construction resists pressures that would otherwise cause the wall to tilt, such as when water trapped on the landward side of a barrier after a heavy storm.

Many excavation support systems and anchored retaining walls use tiebacks to provide lateral resisting force. They are built by grouting a high strength steel bar or strand bundle into the soil or rock beneath the retaining wall’s failure surface.

 

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